The Analog vs Digital
Conundrum:
Mixed Signal Integration
Solutions and Challenges
for Unmanned Systems
DUNCAN BOSWORTH
DIRECTOR MARKETING & APPLICATIONS
AEROSPACE & DEFENSE
Aerospace and Defense: UAV Challenges
Market
Challenges
•
•
Advanced and
evolving threats
drives insatiable
demand for
advanced payload
technology
Continuous drive
for SWaP reduction
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ADI
Focus
Solution
Requirements
•
•
•
Higher frequency
of operation
Operation in
contested
environments
Modular and
multi-function
architectures
•
•
•
Complete uWave
and mmWave
solutions
Advanced, novel
& customizable
architectures
Increased
integration and
scalable solutions
UAV System Challenges & Technology
►
Flight Control and
Stabilization
GPS systems
GPS denied
Accelerometer & Gyro
Stabilization systems
►
Communications for
Control & Data Relay
Line of Sight (LoS)
Beyond LoS
SatCom
►
► Size,
Active
Passive Systems ADSB
etc.
Weight and Power (SWaP)
Typically dominate system developments
Advance payload demands challenge limitations
System
Power
Battery
/ Fuel
Needs
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Collision Avoidance
Platform
Weight
►
Advanced Payloads
Vision Systems
Electronic
Countermeasures &
Surveillance
Radar Imaging
SWaP Challenges for UAV Systems
Large Platform
Challenge:
Multi-function payloads
Long Range SatCom
Multi-Sensor
SWaP Challenge: Enabling
Large Platform
Challenge:
FAA Approval –
DO254/DO178 challenges
Collison Avoidance
SWaP Challenge:
Med / Small Platform
Challenge:
LOS Comms in
congested environments
SWaP Challenge: Power vs linearity
Nano Platform
Challenge:
Onboard Processing to
reduce comms power
SWaP Challenge:
Size!!!
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Traditional RF & uWave System Architectures
Current solution for Communications & Radar
Traditional Superheterodyne Receiver
•
•
UHF & L Band communications
L, Ku & Ka SatCom systems
•
•
•
►
Advantages
Widely used and understood
High performance
Discrete components available for
all functions
Low Cost GaAs based devices
Electronic Surveillance Systems
Weather Radar
Collision Avoidance Systems
►
Disadvantages
Frequency planning challenges
Large Size – high component
count
Complex PCB layout
High Power
Wide Freq Coverage requires
parallel implementations
New Solutions Required to Meet Next Gen Systems
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The Digital & Analog Boundary
Can digital Solve the SWaP Problem?
Calibration and Tracking : Determine analog errors and provide analog bias or other adjustments
Digitally Assisted Analog : Provide linearization / error correction compensation post Digitization
Digital Signal Processing : Reduce Processor Loading and Optimize Data Distribution
Digitize Closer to the Antenna:
Reduce component count
Pull DSP functions
forward : Reduce IO
Power
Digital correction &
Lineation: Enables new
architectures and
solutions
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Wide bandwidth digital
calibration: Reduce
component count
UAV Communications SWaP solved by Direct Conversion?
Digital Compensation in CMOS enables high performance
► Direct
conversion
Architectures
Lowest power: process only
the desired band at the lowest
possible frequency
Best out-of-band performance:
no images, NXM mixing
products …
Smallest size: eliminate some
filters and relax others
Lowest system cost
Reduces filters:
Reduce cost and volume and
increase flexibility
► Challenge
: Quadrature
Error
Digital Assistance
implemented in CMOS
mitigates issue
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ADC
ADC
Synth/
VCO
LOgen
Digital.
Decimate
QEC
Dc offset
AGC
RSSI
BW tune
ClkGen
Digitally Assisted Analog
• Digital processing implemented in CMOS
• Correct Analog Errors
• I/Q matching,
• Digital detection with analog correction
• Zero power correction
• Correction tracks temperature
• Infrequent updates
• Better dynamic performance
JESD204b
Eample : Direct Conversion SW-Defined RF Transceiver ICs
Provides Increased Integration
►
One device for all
UAV comms bands
915 MHz ,
2.4 GHz and
5.8 GHz UAV
►
Implements MIMO
►
Reduces component
count
LNA + PA + AD9361
Typical Features now integrated in CMOS
►
►
LNA
IQ Mod / Demodulators
Analog Gain Control & Attenuation
Tunable Analog Filters
ADCs / DACs
Digital Filtering
QEC correction
PLL / VCOs
Highly Flexible
Tunable 70 MHz to 6.0 GHz
200 kHz to 56 MHz channel bandwidth
Superior receiver sensitivity
with noise figure <2.5 dB
Highly-linear broadband transmitter with
EVM: ≤ -40 dB
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10x10mm
144-Ball Chip Scale
Package Ball Grid Array
Example: Low SWaP uWave SatCom
Baseband
Processor
ADC
uWave
Devices / Modules
Up/down converter
Integrated
Transceivers
AMP
MXR
LNA
MXR
ADC
►
Extend TRx front-end for
X, Ka, Ku band
►
Benefits:
AMP
MXR
ADC
AMP
MXR
LNA
MXR
ADC
AMP
MXR
DAC
Flexible frequency planning
Reduced component count
system
AMP
MXR
DAC
MXR
AMP
MXR
DAC
AMP
MXR
DAC
MXR
AMP
MXR
9
RF & uWave devices for up /
RF
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down conversion from Ku bands
Transceiver
TRx device optimized and
simplified filters
Modular architecture
between VHF to C and
uWave systems
Example : Collison Avoidance or Radar Payloads:
RF Sampling / Higher IF Conversion Using CMOS Converters
►
Typical superhet implementation inflexible & high component count
►
Digitally Calibrated and Assisted CMOS ADCs & DACs offer alternative approach
►
Moves to a more digital approach
Increases System Flexibility
Reduces Component Count and Power
►
RF sampling L & S band
L&S band systems
Direct RF sampling
No Mixing stages
►
X, Ku and Higher
Removes second IF
System size reduced to single analog
mixer
Second analog mixer replaced by Digital
Down Conversion (DDC).
►
Integrated DDCs
Increase system configurability
Increased Agility
Dynamic changing from Wideband to
Narrowband system
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X & Ku band with no 2nd IF
Integrated CMOS DDC
Replaces Analog Mixer : Increase Flexibility & Reduce Power
►
Moves to a more digital approach
No Quadrature Error
Increases System Flexibility : Faster tuning
Reduces Component Count
System Power reduced with decimated output data reducing IO Bandwidth
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Example : Wideband Surveillance UAV Payloads
SiGe & Digital Calibration reduce parallel signal chains
►
Requirement to survey 2-18GHz previously required multiple PLLs, mixers etc
Parallel signal paths and switches
►
SiGe BiCMOS process
Supports digital ancillary functions
Digital calibration for wideband functionality
Example : Advanced PLLs
Integrated VCO – reduces size
RF outputs from 54 MHz through to 13.6 GHz supports multi-mode
Multiple separate integrated VCOs cores.
Correct VCO and band are chosen automatically using digital calibration logic integrated inside the device.
256 overlapping bands
allows the device to cover a wide frequency range without requiring large VCO sensitivity
Does not sacrifice phase noise and spurious performance
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Summary
►
UAV Systems challenge todays SWaP
boundaries
Comms & control systems
Advanced Payloads
►
►
CMOS and SiGe devices enable new
reduced component count & low power
systems
►
Digitally assisted analog and RF
functionality
►
Remove the analog / digital devide
Challenges in both military and
commercial systems
Power = fuel / batteries = weight
Weight reduces mission life or payload ability
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Thank You
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