Kevin Parkinson

RF Design for GNSS receivers

IGNSS 2016, 6-8 Dec 2016, UNSW,Sydney | 2

• The KEA GNSS receiver • Receiver architecture • RF Down-converters • Design Challenges • Results

Contents

IGNSS 2016, 6-8 Dec 2016, UNSW,Sydney | 3

Kea V4.1SB Receiver Module • Credit card sized • SmartFusion2 SOC

– Large flash based FPGA with 50k or 80k logic elements and enhanced SEU immunity

– Powerful 166 MHz ARM Cortex M3 processor • 512 Mb of SECDED LPDDR SDRAM • 8 MB of serial Flash • 8 kB of FRAM (ferromagnetic RAM) • CMOS RF ASIC capable of L1/E1 operation • Super-capacitor powered RTC • Support for disciplined VC-TCXO and reference frequency output • USB2 interface for debugging and data-capture

IGNSS 2016, 6-8 Dec 2016, UNSW,Sydney

Typical GNSS Receiver

IGNSS 2016, 6-8 Dec 2016, UNSW,Sydney

RF Down converter ASIC

IGNSS 2016, 6-8 Dec 2016, UNSW,Sydney

Design challenges Paramater Affected performanceNoise figure System sensitivity & Signal-to-noise ratioFrequency plan Image rejection & Interference rejectionIF Topology Noise, Imgage rejection & Intermodulation distortionLNA type Signal-to-noise ratio & Intermodulation distortionMixer type VCO leakage, Signal-to-noise ratio & Intermodulation distortionVCO leakage Local interference & Intermodulation distortionIF bandwidth Image rejection, Selectivity & Interference rejectionVCO Phase noise Signal-to-noise ratioIntermodulation Signal-to-noise ratio & Dynamic rangeDynamic range Sensitivity & Interference tolerancePower consumption Signal-to-noise ratio & Dynamic rangeCross modulation Signal-to-noise ratio & Dynamic rangeLinearity Signal-to-noise ratio & Interference tolerance

IGNSS 2016, 6-8 Dec 2016, UNSW,Sydney

Single frequency ASIC • 4 to 24MHz BW • 60 dB AGC

range • 2 Bit ADC • 75dB Gain • 3.9dB NF • 4 or 12MHz IF • 32MHz sample

2 BitA/D

IF AMP

Synthesiser and PLL

AGC

REFINPUT

MIXER

/2 vco

LNA

SPI Control

MAG

SIGNRFIN

SPI

IF

IGNSS 2016, 6-8 Dec 2016, UNSW,Sydney

Dual Frequency ASIC • 32 MHz BW • 60 dB AGC

range • 3 bit ADC • 75 db Gain • 6.9 db NF • 16 MHz IF • 32 MHz

sample

IGNSS 2016, 6-8 Dec 2016, UNSW,Sydney

Single frequency results Parameter L5/E5a L2 L1Frequency 1176.45 MHz 1227.6 MHz 1575.42 MHzNF 3.9dB 4dB 7dBGain 75dB 74dB 75dBVSWR In 1.5:1 1.45:1 1.52:1Power 0.6W 0.6W 0.6WIP3 -17dB -17.5dB -18dBPN 100KHz -107dB/Hz -110dB/Hz -117dB/Hz

IGNSS 2016, 6-8 Dec 2016, UNSW,Sydney

Dual frequency results Parameter L5/E5a L2 L1Frequency 1176.45 MHz 1227.6 MHz 1575.42 MHzNF 6.9dB 6.8dB 7dBGain 75dB 74dB 75dBVSWR In 1.5:1 1.5:1 1.5:1Power 1W 1W 1WIP3 -17dB -17.5dB -18dBPN 100KHz -94dB/Hz -95dB/Hz -97dB/Hz

IGNSS 2016, 6-8 Dec 2016, UNSW,Sydney

L1/E1 IF out

IGNSS 2016, 6-8 Dec 2016, UNSW,Sydney

L5/E5 IF out

IGNSS 2016, 6-8 Dec 2016, UNSW,Sydney | 13

Thankyou