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A Delta–Sigma modulator-based heterodyne FMCW radar for short-range applications

Published online by Cambridge University Press:  18 March 2014

Reinhard Feger*
Affiliation:
Christian Doppler Laboratory for Integrated Radar Sensors, Institute for Communications Engineering and RF-Systems, Johannes Kepler University Linz, Altenbergerstr. 69, Linz 4040, Austria. Phone: +43 732 2468 6391
Herman Jalli Ng
Affiliation:
Christian Doppler Laboratory for Integrated Radar Sensors, Institute for Communications Engineering and RF-Systems, Johannes Kepler University Linz, Altenbergerstr. 69, Linz 4040, Austria. Phone: +43 732 2468 6391
Clemens Pfeffer
Affiliation:
Christian Doppler Laboratory for Integrated Radar Sensors, Institute for Communications Engineering and RF-Systems, Johannes Kepler University Linz, Altenbergerstr. 69, Linz 4040, Austria. Phone: +43 732 2468 6391
Andreas Stelzer
Affiliation:
Christian Doppler Laboratory for Integrated Radar Sensors, Institute for Communications Engineering and RF-Systems, Johannes Kepler University Linz, Altenbergerstr. 69, Linz 4040, Austria. Phone: +43 732 2468 6391
*
Corresponding author R. Feger Email: [email protected]

Abstract

We present a heterodyne frequency-modulated continuous-wave (FMCW) radar, applicable in short-range applications. Owing to a modulation of the transmit (TX) signal, the intermediate frequency (IF) signal can be shifted away from zero frequency to reduce the influence of dc-offsets and low-frequency disturbances like, e.g. flicker noise existing in components like mixers, amplifiers and analog-to-digital converters. The presented system is based on E-band transceivers realized in SiGe technology, which are fully integrated with antennas in a plastic package. A sinusoidal modulation of the TX signal is realized by a binary phase-shift keying modulator, which is controlled by a Delta–Sigma sequence. The choice of a sinusoidal modulation allows to reuse signal processing blocks which are typically available in FMCW radars. Measurements show that the achievable signal-to-noise ratio is comparable to a homodyne realization since the Delta–Sigma noise can be filtered in the IF stage. Experiments with a bandwidth of 8 GHz demonstrate measurements down to 12 cm with standard deviations of the measured ranges lower than 60 µm. Compared to a homodyne realization the blocking distance could be reduced by approximately 40 mm.

Type
Research Paper
Copyright
Copyright © Cambridge University Press and the European Microwave Association 2014 

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