Configurable
RF Architecture Gives
Engineers Greater Design
Flexibility
Ahmad Chaudhry and Jim Goings
In the automotive environment, RFenabled sub-systems continue to
evolve and proliferate. Such systems
include Tire Pressure Monitoring
Systems (TPMS), which are mainly
unidirectional on a single RF channel at
relatively high data rates; Remote Start
(RS) systems, which are generally
bidirectional on single or multiple
RF channels at relatively low data
rates; Passive Keyless Entry (PKE)
and Remote Keyless Entry (RKE)
applications, which are unidirectional
on single or multiple RF channels at
moderate data rates. TPMS uses both
On Off Keyed (OOK) and Frequency
Shift Keyed (FSK) modulation, RS uses
OOK only, and RKE uses either OOK
or FSK. To accommodate such multiple
systems and applications, automotive
RF semiconductor devices must
possess flexible as well as configurable
architectures. The need for architectural
flexibility, combined with customer
expectations of high performance,
improved range, and reliability, is driving
the next generation of RF IC designs.
Beginning with range and reliability,
improvements here are easier to
realize when the transmit path has
programmable parameters. One can
1
usefully employ a Power Amplifier
(PA) with reserve capacity, which can
be trimmed in output power level to
provide the maximum allowable output
in accordance with local regulatory
requirements. Further benefit can be
obtained from a PA whose output
impedance can be trimmed to optimize
the antenna match. Range and
reliability gains on the receive side can
be enhanced through proper selection
of sensitivity-related parameters,
such as RF carrier frequency, subchannels, modulation, data rate, and IF
bandwidth.
and RS. The devices also support all
automotive bands: 310 to 318MHz,
418 to 477MHz, and 836 to 928MHz
and use one device and a single crystal
frequency.
These two devices are also designed
for architectural flexibility. A dualLNA architecture with two separate
input pins natively supports multiband applications using one single
IC, PCB, and bill of materials (BOM).
Additionally, dual-parallel demodulation
paths support simultaneous ASK and
FSK sensing capability. These features
Atmel Has Introduced Next-Generation Transceiver
And Receiver Devices With Configurable Options
Flexibility for the design engineer
is also gained through access to a
receiver in which these parameters are
available as a programmable option.
Atmel® has introduced next-generation
transceiver and receiver devices
with these configurable options.
For example, the Atmel ATA5830
transceiver and Atmel ATA5780
receiver can accommodate automotive
applications such as RKE, PKE, TPMS,
accommodate multiple polling schemes
including TPMS, RS and up to three
RKE channels, and can be configured
to support RF protocols across multiple
frequency bands, modulation schemes,
and data rates.
To implement the vast array of
configurable content in both Atmel®
devices, the desired configuration
settings are stored in the built-in
EEPROM and automatically applied to
© 2010 / www.atmel.com
(Optional)
(Optional)
PB3
PB4
PB5
PB6
PB7
AGND
TEST
_
102
SPDT_RX
RFIN
_HB
SPDT_ANT
SPDT_RX
PB3
PB4
PB5
PB6
PB7
PB2
23
24
22
23
DGND
PB0
21
22
DVCC
DGND
20
21
PC5
DVCC
19
20
PC4
PC5
18
19
PC3
PC4
17
18
Atmel
SPDT_TX
ANT_TUNE
RF_OUT
SPDT_TX
PC2
PC1
PC0
VS
AVCC
XTAL2
XTAL1
VS_PA
XTAL2
VS_PA
RF_OUT
PC3
PC2
PC1
PC0
VS
AVCC
TEST_
EN
10 11 12 13 14 15 16
9
24
PB1
PB2
PB0
PB1
ATA5830
Atmel
ATA5830
ANT_TUNE
SPDT_ANT
9
AGND
TEST
_
102
32 31 30 29 28 27 26 25
TEST_
EN
8
RFIN
_LB
RFIN
_HB
RFIN
_LB
XTAL1
1
1
3
1
4
3
5
4
6
5
7
6
8
7
ATEST
_
101
1
ATEST
_
101
32 31 30 29 28 27 26 25
17
10 11 12 13 14 15 16
VS = 3V
Elements
Number
Inductor
Elements
Capacitor
2Number
(3)
Matching
Comments
72(9)
3Matching
(5) for matching
(3)
43for
Blocking
7 (9)
(5)
for matching
Crystal
1
Capacitor
Inductor
Crystal
1
VS = 3V
Comments
14single
crystal for 3
for Blocking
different frequency ranges
1 single crystal for 3
different frequency ranges
Figure 1. Atmel ATA5830 Transceiver Application Circuit
SPDT_RX
RFIN
_HB
SPDT_ANT
SPDT_RX
N.C
N.C
MISO
PWPON
LED1
NSS
ATA5780
MISO
PWPON
LED1
24
SCK
MOSI
NRESET
VS
AVCC
XTAL2
NRESET
XTAL2
NPWRON3
TMDO
VS
AVCC
10 11 12 13 14 15 16NPWRON2 17
TEST_
EN
9
XTAL1
9
MOSI
23
24
CLK_OUT
SCK
22
23
DGND
CLK_OUT
21
22
DVCC
DGND
20
21
NPWRON5
DVCC
TRPB
19
20
NPWRON4
NPWRON5
TRPB 18
19
NPWRON3
TMDO
NPWRON4
NPWRON2 17
18
TRPA
NPWRON1
NPWRON1
N.C
N.C
N.C
NSS
Atmel
ATA5780
Atmel
N.C
SPDT_ANT
N.C
N.C
AGND
AGND
RX_Active
RX_Active LEDO
LEDO
NPWRONG
NPWRONG
IRQ
IRQ
TEST
_
102
TEST
_
102
32 31 30 29 28 27 26 25
TEST_
EN
8
RFIN
_LB
RFIN
_HB
RFIN
_LB
XTAL1
1
1
3
1
4
3
5
4
6
5
7
6
8
7
ATEST
_
101
1
ATEST
_
101
32 31 30 29 28 27 26 25
TRPA
10 11 12 13 14 15 16
NSS
MISO
MOSI
NSS
MOSI
VS = 4.5v to 5.5v
Microcontroller
SCK
Elements
Number
Inductor
Elements
1Number Matching
Comments
41
1Matching
for matching
Capacitor
Inductor
Capacitor
VS = 4.5v to 5.5v
Microcontroller
MISO
SCK
Crystal
Crystal
4
1
1
Comments
31for
forBlocking
matching
13single
crystal for 3
for Blocking
different frequency ranges
1 single crystal for 3
different frequency ranges
accessible firmware, making it
possible to develop an entire
application using just one single IC.
Both the ATA5830 transceiver and
the Atmel ATA5780 receiver are also
highly integrated, requiring very few
external components. The application
circuits (see Figures 1 and 2) show
a standard implementation of each
device. For a typical application, the
ATA5830 transceiver only requires 10
external elements and the ATA5780
only six external elements. Both
devices are packaged in a 5 x 5mm,
32-pin QFN package.
In conclusion, the
newest generation
of configurable Atmel
RF semiconductor
devices provides the
design flexibility needed
for rapidly evolving
automotive RF-enabled
subsystems .
Figure 2. Atmel ATA5780 Receiver Application Circuit
Atmel Devices Also Have Enhancements Which
Simplify Design and Reduce BOM Cost
the device on power-up. This enables
autonomous (stand-alone) operation
and polling for incoming signals from
multiple RF systems with differing RF
carrier frequency bands, modulation
formats, and data rates. Stand-alone
operation allows an external controller
to sleep while the device polls,
validates start of frame, and checks for
proper transmitter ID data. The device
only wakes the controller when a valid
message is detected. This is critical to
reducing Ignition Off Draw (IOD) in
Automotive Compilation Vol. 7
vehicle-mounted applications and to
extending battery life in handheld fob
applications.
Atmel devices also have some other
enhancements which simplify design
and reduce BOM cost. The Atmel
ATA5830 transceiver device, for
example, has an embedded Atmel
AVR® microcontroller on the same
silicon die. The microcontroller
includes 6kByte of Flash and a
24kByte ROM library of user-
2