Design of a ±0.15 dB accurate baseband detector for FMCW radars employing inherent PVT cancellation

Mohammed El-Shennawy; Niko Joram; Frank Ellinger

Design of a ±0.15 dB accurate baseband detector for FMCW radars employing inherent PVT cancellation

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Author(s): Mohammed El-Shennawy ¹ ; Niko Joram ¹ ; Frank Ellinger ¹
- Affiliations: 1: Chair for Circuit Design and Network Theory, Technische Universität Dresden, 01062 Dresden, Germany
Source: Volume 11, Issue 2, March 2017, p. 157 – 165
DOI: 10.1049/iet-cds.2015.0352 , Print ISSN 1751-858X, Online ISSN 1751-8598

Received 22/04/2016, Accepted 02/08/2016, Revised 28/07/2016, Published 01/03/2017

This study presents design methodologies for high accuracy baseband detectors for use in automatic gain control (AGC) loops. These loops are used in many applications to stabilise the signal level in a transceiver chain. In a wireless frequency modulated continuous wave (FMCW) radar receiver for example, it is desired to maintain a constant baseband signal level at the receiver output prior to the analogue-to-digital converter. Due to the AGC loop feedback action, the accuracy of this output level directly depends on the detector accuracy. In this study, a detector design employing inherent cancellation of process, voltage and temperature (PVT) variations without the need for any complex compensation schemes is proposed. Measurement results of a fabricated test chip are in good agreement with simulations achieving ±0.15 dB accuracy over temperature, supply and part-to-part variations. The fabricated detector prototype on an IBM 0.18 µm technology has an active area of 0.05 mm² and draws 1 mA from a 3 V supply. An integrated AGC loop including the proposed detector achieves a 52 dB dynamic range consuming an overall 9 mW power. To the best of the authors’ knowledge, the proposed detector has the highest uncalibrated accuracy reported up to date.

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Design of a ±0.15 dB accurate baseband detector for FMCW radars employing inherent PVT cancellation

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