June, 2010
RF Design Considerations for 802.15.4
Hardware Development
FTF-ENT-F0515
Mark Williams
Applications Manager
TM
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
Course Objectives
► After
•
•
•
•
•
•
completion of this course you should:
Understand the requirements of RF and wireless design
Understand the function of antennas and RF matching networks
Understand the special requirements of RF PCB layout
Understand the benefits of using Freescale’s 802.15.4
reference designs
Understand how to verify your design
Understand the need for, and requirements of, certification
► This
course will NOT make you an RF engineer. But you will gain an
appreciation for the specialty of RF engineering, and be able to provide
guidance for experienced hardware engineers to create successful
802.15.4 designs
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
2
Agenda
► Introduction
► RF
Hardware Design Philosophy
► Antennas
► Design
► The
and RF Matching Networks
and Board Layout Considerations
Use of Reference Designs
► Design
Verification Methodology
► Certification
► Summary
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
3
Introduction
► Why
does RF design seem like “black magic”?
•
Parasitics that can be ignored in low-frequency analog and digital circuits
have a major impact on radio frequency circuit performance
•
Models are usually much less accurate, requiring more
empirical design work
•
Wireless hardware designs (cellular, Bluetooth, Wi-Fi, 802.15.4, etc.) are
“intentional radiators” so they have special certification requirements
•
Design and test of wireless hardware requires special equipment
and skill for digital and analog designs
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
4
RF Hardware Design Philosophy
► Every
trace on a circuit board is a circuit element that cannot be ignored
Circuit traces become transmission lines of a given electrical length
• Short lengths of line tend to be capacitive, longer length inductive
•
► Ground
connections are difficult to create since “every trace is a
circuit element”
► Any
► RF
conductor will be a radiator — i.e. an antenna — at RF frequencies
design techniques need to be applied above a few hundred MHz
► Chip
components become complex circuits above a few hundred MHz
► High
power RF (> 20 dBm) accentuates these issues
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
5
Antennas and RF Matching
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
6
What Is an Antenna?
► IEEE®:
A means for radiating or receiving radio waves.
► Sayre:
To convert RF energy (alternating current) into electromagnetic
waves (or vice-versa), as efficiently as possible.
► Skolnik:
A transducer between free space propagation and guided wave
propagation.
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
7
What is an Antenna?
►
Antennas are used at frequencies as low as 30 Hz (submarine ELF,
extremely low frequency) up into the hundreds of GHz (EHF, extremely
high frequency). This presentation focuses on 2.4 GHz applications.
►
The characteristics of the antenna (gain, impedance, polarization, size,
cost, etc.) should suit the application.
►
This means that an antenna suitable for one application may not be
efficient for another.
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
8
Antenna Selection Considerations
► When
selecting an antenna,
one must consider:
•
•
•
•
•
•
•
•
•
•
Cost
Size
Gain/directivity (pattern)
Reliability (durability)
Manufacturability
Bandwidth
Polarization
Input impedance
Power handling
Connector type (if any)
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
9
Antenna Selection Considerations
► In
a 802.15.4 applications, cost, size and pattern are usually the
most important.
►A
few designs, such as the inverted F-antenna or bent dipole, will be
suitable for most ZigBee® applications that use a PCB antenna.
► Special
designs may sometimes be needed, such as a chip antennas
due to size limitations, or an external whip for outdoor applications.
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
10
Antenna Basics
►Antenna
•
Gain
dBi is the most common reference used
for antenna gain. This is gain referenced
to an “isotropic” antenna, which is a
theoretical perfect sphere which radiates
equally in all directions (0 dB gain in all
directions)
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
11
Antenna Basics
► No
such antenna actually exists, but it
serves as a good reference standard.
► Sometimes
dBd, which is gain
referenced to a horizontal dipole in
space, is used. Most references
define 1 dBd = 2.14 dBi. A horizontal
dipole at the correct spacing above a
ground plane can have gain greater
than 2.14 dBi.
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
12
Antenna Terms
►
Peak gain: The maximum gain of an antenna.
►
Average gain: The average of antenna in all directions.
►
Efficiency: The ratio of radiated power to supplied power.
Typically 20% to 90%.
►
Null: A significant dip in the gain of the antenna in
a particular direction.
►
Directivity: The power in the ”main beam” or highest gain direction of an
antenna compared to isotropic, expressed as a ratio.
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
13
Is High Antenna Gain Always Good?
► Gain
in one direction is only obtained by reducing gain in another direction.
That is, a “high gain” antenna only has gain in one or more directions. In
other directions, the gain is significantly reduced (nulls).
► Proper
antenna orientation is required to ensure that the gain peak is
aimed towards the desired signal.
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
14
Is High Antenna Gain Always Good?
►So,
high gain is not always good(!). For handheld or portable
applications where the orientation of the device is not controlled,
a high-gain, highly directional antenna may not work very well for
the end user.
►High-gain
antennas can work very well in fixed applications.
(from TP8347)
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
15
The Dipole
► The
horizontal ½ wave dipole is the most basic antenna.
► The
radiation pattern is ”doughnut” shaped, a null from the end of each
radiator. The impedance at the feedpoint is 73 ohms for a perfect
theoretical dipole, at the resonant frequency.
► The
dipole is a balanced, differential structure.
The basic dipole:
Total length is ½ wavelength,
(At 2.4 GHz, approx.
6.1 cm in air)
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
16
Bent Dipole
► The
ends of a dipole can be bent to reduce
the horizontal space required.
Dipole shapes to reduce
width and improve the
omnidirectional
characteristics:
► By
bending the dipole, the end nulls will
often be filled in, at the expense of some
forward gain.
► Changing
the shape may also change the
impedance and/or the length at resonance.
► The
Freescale 13192 SARD used a bent
dipole antenna.
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
17
The Monopole
►
By substituting one leg of the dipole with a conductive ground plane, the
remaining part of the dipole ”mirrors” itself in the ground. For a perfect
infinite ground plane, the feedpoint impedance is half that of a horizontal
dipole, or 36 ohms.
►
The ground plane can be the ground plane of a PCB board or metal case.
A monopole
above a ground
plane, showing
the “mirror”
antenna.
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
18
The Monopole is VERY Ground Plane Dependent
►A
ground plane needs to be
approx. 6 times the
wavelength in diameter to
act as a theoretically
”infinite” ground plane.
► Anything
smaller will
change the pattern from the
ideal. In general, as the
ground plane gets smaller,
the peak in the pattern
moves up from horizontal,
to as high as 30 - 40
degrees above horizontal.
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
19
Inverted F-Antenna
► By
bending the monopole into an inverted L shape, the omnidirectional
characteristics are improved, but efficiency is slightly lower and impedance
is much lower.
► By
”tapping” the monopole we get the inverted F-antenna with good
omnidirectional characteristics and a 50 ohm impedance point.
► The
F-antenna is a good all-around antenna. It is very commonly used,
including on Freescale 802.15.4 evaluation boards.
Tilted whip and F-antenna:
(note the ground plane area)
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
20
Other Antenna Types
► Many
other antenna types exist. Patch antennas have a patch of metal over
a ground plane, and are very directional (used for GPS). Loop antennas are
also used in PCB applications. Slot antennas can be thought of as dipoles
cut out in metal plates. They are often used in microwave applications.
Half-wave and quarter-wave slot antennas:
Patch antennas:
A metal patch over a ground plane
Half-wave and full-wave loops:
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
21
Chip Antennas
►A
lot of different chip antennas exist on the market. The usual principles of
operation are monopoles, helixes and patch antennas.
► The antennas are made of a low-loss ceramic with high dielectric constant.
The high dielectric constant (approx. er=10) shortens the physical length of a
wavelength in the material.
► Be careful when
comparing size:
The actual chip antenna
may be very small, but
often requires a much
larger cleared area
and ground plane to
be efficient.
► Typical gain ranges from –10 to –2 dBi.
(Johanson Technology)
Good for very short range applications, such as
wireless mouse, keyboard, some remote controls, etc.
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
22
Printed Antenna Use Considerations
► Antenna
•
design requires specialized tools and experience
Don’t change a design unless you know what you are doing and are
ready for multiple board spins and time on the bench
►A
design is optimized for a particular PCB material and thickness.
Changing either will impact the design
► Metal thickness is usually not a concern
► Grounding is critical and ground vias are part of the antenna design
► Follow a reference design EXACTLY
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
23
Using Chip Antennas
►
Just placing a chip antenna on a PCB layout does not ensure good
performance. The bandwidth of the chip itself is very narrow. External
matching circuits are used to broaden the response (and center it in-band).
Also consider:
Each design must be tuned on the layout and case for which it is placed.
• Performance can vary due to production variations.
• Consult closely with the manufacturer for applications guidance.
•
Johanson Technology, Chip Antenna Layout Considerations for 802.11 Application
Centurion Technologies, NanoAntTM Application Note
Murata Manufacturing Company, Application Note of Chip Dielectric Antenna M1 Series/W1 Series
Mitsubishi Materials Corp., TRJC-2F03, Recommended Mount Conditions for 2.4 GHz
Pulse/Technitrol, Application Note, WLAN 2.4 GHz. Antenna
Yageo, High Frequency Products (lf28429.pdf)
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
24
“Antenna” Matching
► What
is normally referred to as “antenna” matching is actually matching
performed for the benefit of the transmitter.
► The impedance of the antenna is transformed to the TX output impedance,
giving maximum power transfer and best overall performance.
► The matching does not usually improve the performance of the antenna — it
delivers more TX power into the antenna.
•
•
•
•
Return loss: A measure of impedance match. Essentially, the loss in power reflected from the
load. Can also be expressed as VSWR.
Bandwidth: The frequency range over which the return loss is acceptable.
Input impedance: The RF resistance of the antenna at resonance (Fo). The impedance will
vary at other frequencies.
Resonance: Frequency where the antenna impedance is purely resistive
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
25
Matching vs. Tuning
►
To tune an antenna, the physical dimensions of the antenna are optimized so
that the antenna itself is resonant as intended.
►
Antenna tune quality is normally measured by measuring reflected power vs.
forward power, or return loss, at the desired frequency(s) of operation. If an
antenna is very lossy, it may not work very well but indicate a good return
loss. But, in most cases, return loss can be used to determine the center
frequency of an antenna.
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
26
Matching vs. Tuning
►
Additional matching may be required if the impedance of the antenna, when
tuned, is not the same as the TX output impedance — for example, to match
a 36 ohm antenna to a 50 ohm RF circuit. Matching is normally accomplished
using passive capacitors and inductors that are intended for use at 2.4 GHz.
►
In some cases, it may be easier to match and tune at the same time. For
example, an antenna that is too short can be matched to 50 ohms in the
desired band with series inductance at the input (such as citizens band radio
antenna with a large coil at the base).
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
27
Balanced-Unbalanced Circuits
►
In many cases, the RF transceiver will have an interface that is balanced — it has
a positive and negative output. This architecture has advantages at the die level,
but usually must be converted to single-ended (one side referenced to ground) for
most RF circuits. Some sort of conversion circuit is necessary.
►
This can be done with a commercial ceramic balun, as shown below (Z100).
It can also be performed with a lumped element balun (L/C).
►
If the antenna is balanced, such as a dipole, and there are no other single-ended
parts such as a TX/RX switch, PA, etc., then it would be possible to stay balanced
thoughout and not use a balun (such as the Freescale SARD board).
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
28
Antennas: Additional Thoughts
► Steps
to good antenna performance
•
The antenna should be reasonably clear of metallic objects, but oriented
properly with the ground plane (when one is utilized).
•
Always check the antenna in its final environment, including the PCB,
components, case, hand effects (if appropriate), battery, etc. Plastic and
other materials in the near-field may cause detuning.
•
Test actual antenna performance by whatever means available, such as
range testing, measuring radiated signal level under controlled conditions,
and/or send it out for testing in an anechoic chamber.
•
Test samples from volume production to check for production variations.
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
29
Antennas: Additional Thoughts
► Steps
•
to good antenna performance
The plastic case will detune the antenna, if the plastic is close enough:
PCB inverted F, no case
PCB inverted F, plastic case in place
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
30
Design and Board Layout Considerations
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
31
Assess Your RF and Wireless Capability
► Successful
wireless hardware development requires some level of RF skill.
RF layout
• Antenna design
• RF measurement capability
•
► You
wouldn’t hire an analog designer to write embedded C code,
so don’t expect digital hardware engineers to be RF experts.
► Decide
whether you want to develop RF hardware expertise and,
if so, to what level.
With investment in some RF test equipment, most hardware engineers can
make basic RF measurements
• RF circuit design, layout and antenna design are specialties requiring
investment in tools and experience
•
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
32
Successful Design Approach
► Select
a chipset vendor with a proven track record
Basic modem performance is a function of the IC design, and an IC
designed for a particular protocol will generally meet the requirements
• Range, output power, harmonic and spurious radiation can all be
affected by the design implementation
•
► Don’t
attempt a discrete or low-level integration design
unless you know what you are doing.
► Use
the manufacturer-recommended reference designs
These have typically been certified and have optimized performance
• Follow the design EXACTLY in the RF region of the board
•
ƒ
•
This does not mean the schematic only, but the LAYOUT
Mixed mode regions are ok to modify, as they generally do not
contribute to RF performance
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
33
Antenna and Connectors
► Regulatory
agencies frown on
detachable antennas
► Only “unique” connector types
and designated antennas will
pass certification
► Integrated antennas or those that are
not removable are the easiest to certify
► Issues:
Some testing is conducted, i.e. with
coax cable
• Radiated testing is difficult
• Ultra-miniature coax connectors with
in-line switches are usually considered
“unique,” allowing easy testing, but
they can impact RF performance.
•
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
34
Modules as an Alternative
► FCC
and other regulatory
agencies allow “modular”
certification: OEM can use
a certified module and does
not have to re-certify.
•
EXCEPTION: If the radio
transmitters are within 20 cm
of each other, the hardware
must be re-certified.
► Excellent
alternative to OEM
design for low-volume
applications or where RF
hardware expertise is lacking.
► Most
chipset manufacturers
have module partners.
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
35
Digital vs. Analog vs. RF PCB Considerations
► Each
•
Digital
ƒ
ƒ
ƒ
ƒ
•
Routing
Balance
Signal isolation
Grounding
Analog
ƒ
ƒ
ƒ
ƒ
•
discipline has its own considerations and priorities in PCB layout
Balance
Shielding
Trance loss
Grounding
RF
ƒ
ƒ
ƒ
ƒ
Parasitics
Controlled impedance
Coupling
Grounding
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
36
RF Layout Considerations
► Non-controlled
•
impedance traces should be kept short
Length traces are lossy and inductive
► Grounding
is imperative
Remember the antenna considerations?
• Lengths of line are NOT ground but inductors
• Consider the concept of “earth” or “chassis” ground
•
► PC
traces are effective radiators at RF frequencies because they are a
non-negligible fraction of a wavelength
► Examples
of PCB Parasitics:
•
At 2.4 GHz, a 10 mil wide PCB trace 275 mils long on 32 mil FR4 is equivalent
to a 3.2 nH inductor, +j73 Ohms.
•
A 10 mil via in 32 mil FR4 is about 0.5 to 1 nH.
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
37
Critical Layout Areas
Critical RF
Circuit Area
Copy Exactly
Less critical
Can be modified
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
38
Critical Grounding and Layout
Via to form
ground plane
for antenna
Crystal close
to the IC
Controlled
impedance line
for long runs
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
Ground via
under and
near the IC
TM
39
Mechanical Considerations
► Consult
Freescale’s ZHDCRM, ZigBee Hardware Design Considerations
Reference Manual
Includes details of recommended footprints, device marking and soldering
information for 802.15.4 platforms
• Some of our reference designs and development hardware may deviate
slightly from these due to CAD issues or contract manufacturer changes.
Either are acceptable
•
► Soldering
of QFN and LGA packages is challenging
Work with a reputable house with experience
• Follow their guidelines for solder stencil design
• Filled vias are recommended for small vias-in-pads such as with MC13224V
• Use a minimum of 5 mils solder thickness to avoid “starvation” of
leaded packages
•
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
40
Use of Reference Designs
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
41
What are Reference Designs?
3.0”
►A
form-factor design example,
essentially ready to build
► Proven
performance
► Excellent
starting point for
OEM design
► Differ
from development boards
in that the circuitry is simpler
and functionally oriented
3.8”
► Freescale
has reference
designs for all platforms
Interface – UART, I2C, KBI
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
42
Development Boards vs. Reference Designs
► MC1321x
SRB Development Board:
Designed for lab use, code
development and experimentation.
Lots of stuff….
► MC1321x
IPB: Basic RF layout with
critical components. Interfaces are
pinned out. Designed to be a starting
point for OEM designs. Also for
add-on to existing hardware
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
43
Freescale 802.15.4 Reference Design Download
► Available
from the web:
www.freescale.com/802154
under development tools
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
44
Available from the Download Page…
► Numbering
Scheme: Platform – Interface, Antenna, Implementation
Interfaces: I = I2C, UART, U = USB
• Antennas: P = Printer, C = Chip
• Exception: ERB = Extended Range Board
•
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
45
The Download Contains…
►ZIP
•
file with:
Design files
ƒ
ƒ
ƒ
•
Documentation
ƒ
ƒ
•
CAD files from OrCAD or Allegro
Gerbers
PDFs of schematic and layers
Reference manual
BOM
Software
ƒ
BeeKit configuration file
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
46
Successful Use of Reference Designs
► Copy
the RF and Analog
area EXACTLY
Critical area
Copy exactly
This is the part of the design
most likely to fail
• Use the same PCB material
and thickness
• Changing the PCB thickness
WILL affect the antenna
requiring tuning
• Copy the IC footprint
•
► Digital
circuitry can be
adapted to the target
application
Less critical
Can be modified
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
47
Design Verification Methodology
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
48
When You Get Your First Prototype Back…
► Perform
a basic “smoke” test with a current-limited power supply
Does the unit turn on?
• Does it draw the expected current?
•
► Check
the RF performance
Use Freescale’s SMAC software or Test Tool (or your own code)
• Check the reference oscillator frequency using a frequency counter
•
ƒ
ƒ
•
Measure output power using a power meter or spectrum analyzer
ƒ
ƒ
•
CLKO pin on MC1321x family, TMR2 and connectivity test on MC13224V
Should be within 10 ppm of the target frequency
May require board modification to make conducted measurements
Expect 1-2 dB variation from data sheet specs and from unit to unit
Measure the range between two boards using packet error rate (PER) software
ƒ
Open space (outdoors) range for Freescale’s reference designs should be
200-300 meters
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
49
Testing and Verification Help
► Consider
using a hardware development partner if you do not
have RF test expertise
Or…
► Work
with a test equipment company such as Agilent or
National Instruments
► Plan
to spend time in the lab and money on test equipment
► Check
out new Freescale RF Test Reference Manual:
ZRFETRM, Freescale IEEE 802.15.4/ZigBee Node RF Evaluation
and Test Reference Manual
• Includes details on how to evaluate your board
• Will be updated to include a section on production testing
•
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
50
Moving on to Pre- Certification Testing
► Once
your design is working, there are some basic measurements
that should be made prior to certification testing
► You
may want to work with your certification lab on your first hardware
design and have them show you how to make the measurements
► FCC
Publication 558074 gives more details on measuring digital radios
► Tests
are performed in continuous modulation transmission mode
(not packet) or PRBS9 random data packet mode
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
51
Certification
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
52
What is Certification?
► International
Telecommunication Union, a branch
of the United Nations, provides guidelines for RF
spectrum allocations
► Sovereign
nations have the right to control radio
transmissions within their borders
► Certification
is the process of testing radio
hardware to demonstrate that it meets the stated
regulations in the country that it will operate in
► Within
this session, we will address intentional
radiators, or RF transmitters, operating in the
2400 MHz “unlicensed” bands
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
53
When is Certification Required?
► Generally,
when electronic hardware will be sold in a country, the
certification requirements of that country must be met.
► Certification
is usually only required once unless changes are made
to the hardware that will affect the RF emission performance.
•
Examples: IC changes and software revisions that do not change radio
performance are acceptable. (See CFR 47 FCC Part 2.1043)
► Some
countries such as Japan require filing notification with the
regulatory agency even if engineering or demonstrations will be
performed with RF-emitting hardware.
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
54
What Regulations Apply?
► For
•
•
•
•
•
operation in the 2.4 GHz band (worldwide):
In the U.S., CFR 47 FCC Part 15.203, 15.205, 15.209 and 15.247
In Canada, RSS-210 which closely follows Part 15
In EU, ETSI EN 300, 301
In Japan, ARIB STD-T66
Other countries generally follow FCC or ETSI
► Consult
an expert!
Hire a respected test and certification lab that has experience with unlicensed
band hardware and can file (or help you file) in the countries of interest
• Hardware labeling and documentation are critical
•
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
55
Pre-Certification Testing
► Following
are some recommended pre-certification tests that should
be performed as part of the design verification.
► FCC
Publication 558074 gives more details on measuring digital radios
► Tests
are performed using Freescale’s SMAC test mode or
connectivity applications in continuous modulation transmission mode
(not packet) or PRBS9 random data packet mode
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
56
Peak Output Power
► Maximum
output power at
which your unit will operate
► FCC
Part 15.247 (b) (3) applies
with a limit of 30 dBm
(measured conducted) and a 6
dBi (dB relative to an isotropic
radiator) gain antenna
► Test
•
•
•
•
•
•
conditions
10 MHz RBW and VBW
Peak detector
Max hold
NOT a band power measurement
Low, mid and high channel
Continuous modulated transmit
mode (not packet)
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
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57
Spurious Emissions - Conducted
► Includes
harmonics, spurs
and spectral mask
► Part
15.247 (c) applies with
limit of -20 dBc
► Test
•
•
•
•
•
conditions:
100 kHz RBW, 300 kHz VBW
Peak detector
Auto sweep with max hold
Full sweep and band edge
Continuous modulation mode
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
58
Spurious Emissions - Radiated
► Similar
to spurious conducted; however, measured in a 3 meter
RF chamber
► Part 15.247 (c) along with limits in 15.209 and 15.205: 500 µV/m
(54 dBµV/m) for average detector since “forbidden bands” are on
either side of 2.4 GHz (2.2 – 2.3, 2.31 – 2.39, 2.483 – 2.5 GHz)
► Most OEM labs cannot make radiated measurements, so
conducted measurements with antenna gain can be substituted
Frequency range
of Harmonic or
Spurious
Emission
Average Limit
Converted from Field
strength to dBm
measured at RF port
Average Field
strength Limit of
Fundamental
(dBμV/m @ 3m)
Peak Field
Strength Limit of
Fundamental
(dBμV/m @ 3m)
Peak Limit
Converted from Field
strength to dBm
measured at RF port
Above 960 MHz
-41.12
54
74
-21.2
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
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59
Spurious Emissions – Radiated (con’t)
► FCC
Publication 558074 specifies continuous modulation mode, not packet
► If
the average limit is applied, a duty cycle correction factor can be used
per 15.35 (b): On time divided by off time in 100 ms
► Since
802.15.4 is a burst-mode, low duty cycle protocol, a reasonable
compromise between ~75 kbps throughput and ZigBee Alliance
specification of no more than 10% duty cycle is 17%. One full packet
transmitted, no acknowledgement received, the packet is retransmitted
3 more times with no acknowledgement:
Maximum 15.4 packet contains 133 bytes
• At 250 kbps data rate, Tb = 4 µs and TB = 32 µs
• 133 byte packet lasts 4.26 ms
• 4 transmitted packets is total on time of 17 ms
•
► Alternatively,
peak limits and conditions can be used. The peak
limit can be applied with no correction factor.
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
60
Spurious Emissions – Radiated (con’t)
► Average
measurement
(typically what most labs do):
•
•
•
•
•
1 MHz RBW
10 Hz VBW
Auto sweep with max hold
Continuous modulated
Duty cycle correction can
be applied
► Peak
•
•
•
•
measurement:
1 MHz RBW
3 MHz VBW
Auto sweep with max hold
Non continuous mode
► DO
NOT use dBµV mode
on analyzer – does not correct
for radiated power
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
61
Duty Cycle Correction Factor
► To
use a duty cycle correction factor, the duty cycle
must be demonstrated
► Use PBRS9 transmit mode
► With spectrum analyzer in zero span, measure on time
and off time in 100 ms
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
62
Power Spectral Density
► Not
normally an issue as
this is set by the modem
and transmitter
► FCC
Part 15.247 (d) applies
with a limit of 8 dBm/3 kHz
► Must
use PRBS9
transmit mode!
► Test
•
•
•
•
•
conditions
3 kHz RBW
VBW > RBW
Sweep = 500 seconds
Max hold
Span = 1.5 MHz
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
63
Summary of Test Modes
► Continuous
transmit modes are available in Freescale SMAC test
software (test mode app and connectivity test)
► For
duty cycle correction factor measurement, use PRBS9 mode
► For
power spectral density measurement, use PRBS9 mode
► For
spurious measurements, use continuous modulated mode
► For
peak power measurements, use continuous modulated mode
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
64
Suggested Reading
►CFR
•
Sections 35, 205, 209, 247
►CFR
•
47 FCC Part 15 – available from the FCC website
47 FCC Part 2.1043 – available from the FCC website
Allowed changes without recertification
►FCC
Publication 558074 – available from the FCC website
(use Google search)
►“Simplifying
FCC Compliance for 802.15.4 2.4 GHz Devices” –
White paper by Glen Moore, Wireless/EMC Manager, National
Technical Systems
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
65
Summary
►Work
with an experienced certification lab to help you determine
which certification requirements apply to your product
►Realistically
assess your RF capability and goals
►Select
a proven chipset vendor and follow their reference
designs exactly for RF layout
►Perform
pre-certification testing or have your certification
partner perform the tests to insure you pass before finalizing
your design and formally submitting it
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
66
Summary
► In
•
this session we have reviewed:
RF hardware design philosophy
ƒ
•
Antennas and RF matching networks
ƒ
•
FSL 802.15.4 reference designs as a valuable OEM design starting point
Design verification methodology
ƒ
•
Guidelines and references
The use of reference designs
ƒ
•
Basic information on terminology, design considerations and antenna options
Design and board layout considerations
ƒ
•
Details of how RF/wireless hardware design differs from digital and analog
The steps to successful design verification
Certification
ƒ
The need for certification and critical pre-certification measurement as
part of design verification
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, mobileGT, PowerQUICC, StarCore, and Symphony are trademarks of Freescale Semiconductor, Inc.,
Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack, CoreNet, the Energy Efficient Solutions logo, Flexis, MXC, Platform in a Package, Processor Expert, QorIQ, QUICC Engine, SMARTMOS, TurboLink
and VortiQa are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2010 Freescale Semiconductor, Inc.
TM
67
TM