Innovative Phased Array Synthetic Aperture Radar

System on Chip for Satellite Applications

Presented by ZHENG Yuanjin

School of EEE

Singapore Space Symposium 2015

Sep. 30, 2015

SAR on Satellite

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• Optical Quality Images at Microwave Frequencies

• Active System – Day and Night Imaging

• Adverse Weather

• Long Stand-off Ability (fine resolution imaging independent of range)

• Coherent Imaging–Interferometric SAR

• Penetration of Materials and Particulates (frequency dependent)

• Detection of Ground Moving Targets

Micro

Satellite

SAR

Module

Circuit

Board

It remains great challenge to payload the mini

SAR in MicroSatellite

Phase Array Radar New Capability: • High-resolution Ku-band spotlight SAR: 0.1m

resolution

• Stripmap SAR at arbitrary angles: 0.3m resolution

• Penetrate coverage moving target indicator

• Near-real-time coherent-change detection

• Extended range operation and 3D imaging

• Interferometer and polarization

• Low weight and power

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Ku Broad and Spot Coverage (Sandia National Lab.)

High Resolution GMTI

Unique and Significant Platform

for Future Radar Technique

L band Interferogram DEM

Navigation and Guidance

First Generation Radar Chip Transceiver

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PA

Balun

Coupler

Driven PA

Chirp Synthesizer

40MHz Reference

Receiver Front-End

LNA VGA BPF ADC 10 bits -30dBm IP1dB

12dBm 20dBm

Differential Outputs

PC104

Chip Transceiver

Chip Photo Chip Testing PCB

BPF

Radar Chip-α2

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Second Generation of Chip Transceiver

Radar Chip-α2: Improved version of Chip-α1, tapeout on Jan.

2015. Chip came back on Late May

Radar Chip-β2: A compact version for phase array and

commercialization, tapeout on Jan. 2015. Chip came back on Late May.

Radar Chip-β1

2cm

1.8cm

8.5 cm

4.5 cm

11.5 cm

7 cm

Chip Transceiver Testing (Delay-Line) Chirp Rate: 0.56MHz/us Cable Length: 7.8m Speed: 0.7 of light

PA

LNA

Coupler

Bandwidth: 1GHz PRF: 0.56KHz

Hann Window

Dechirped Spectrum (using Matlab)

Mainlobe Freq 14KHz

PSLR -18.5dB

ISLR -10.55dB

Chip Transceiver Testing (Antenna Field Testing)

Coupler

PCB Receiver

Scene of the Dechirping testing

PA

To spectrum analyzer

3dBm 15dBm

11dBm

6dBm

12dBi

12dBi

1.5m

29dB gain

0.2m cable 7

Chip Transceiver Testing (Ranging Performance)

11.46KHz

Dechirped Spectrum (1GHz BW 1ms of sawtooth)

Testing Setup Parameters

Bandwidth 1GHz (Sawtooth)

PRF 1KHz

Centre Freq. 16GHz

RF Cable 0.2m

Distance R 1.5m

3 8

9 3

2

11.46 10 3 100.2

2 1 10 1 10

1.519

bcable

f cR L

BW PRF

m

Distance Measured:

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Chip Transceiver Testing (2 Targets Ranging)

Coupler

PCB Receiver

Scene of the Dechirping testing

PA

To spectrum analyzer

3dBm 15dBm

11dBm

6dBm

12dBi

12dBi

29dB gain

1st Reflector Small RCS

and not pointed by antennas

2nd Reflector Large RCS

Chip testing board

Antennas

1st Reflector

2nd Reflector

~13dB

Chirp Rate: 0.56MHz/us 1GHz BW, 0.56KHz PRF

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Miniaturized Phase Array SAR Sensor System

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We are targeted miniaturized, low power, low cost SAR sensor for Micro-Satellite applications

Reduction of Size/Weight/Power/Cost (X 10-50) Performance improvement (X5)Bulky System

Modular System

Integrated Phase Array TRX IC ChipDigital Proc. System RF Front-end Modules

Highly integrated IC chips with hybrid microwave modules will be the ultimate solution for miniaturizing radar systems

3D Packaging

Integrated Transceiver

Chip

Leakage Cancellation

• Consists of mainly 3 sub-modules: error detector, vector modulator, and DSP control.

• Detects the magnitude and phase of the leakage signal by error detector

• Leakage is then subtracted at the LNA input.

• >30 dB cancellation

Ref: A Ka-Band FMCW Radar Front-End With Adaptive Leakage Cancellation

RF spectrum before and after the leakage cancellation for MTI mode at 26 GHz

RF spectrum before and after the leakage cancellation for SAR mode at 26 GHz

Leakage cancellation scheme

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Fast Chirp : Gear shift and two point modulation • Gear-shift technique

– PLL close loop transfer function is dynamically adjusted

– < 1μs frequency switch

• 2-point modulation – Low pass input at FCW – High pass input at DCO input – PLL loop bandwidth is effectively extended to

infinite. – Enable sweeping over a large bandwidth in

short sweep cycles. – ~ 200 μs fast chirp

Ref: A 4-GHz All Digital PLL With Low-Power TDC and Phase-Error Compensation

Measured frequency characteristics of FMCW signal for (a) Tmod=1.68ms, BW=1 GHz; (b) Tmod=0.42ms, BW=1 GHz Frequency settling

DPLL with gear shift and 2-point modulation

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Phased Array Transceiver • X band FMCW phased array • 8 channels • Signal generated from DDFS • Phase resolution 0.6 degree • Phase angle: ± 30 degree

Ref: A Frequency-Modulated Continuous Wave Phased Array Marine Radar System Based on Smart Antenna Technology

System block diagram of the beamformer consisting of 8 FMCW transmitters array Measured radiation pattern with beam-forming

antenna

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