Analysis and Experimental Validation of Large-Signal Linearization for Low-Power Complex OTA-C Filters

Abstract

This paper presents a second-order complex baseband operational transconductance amplifier-capacitor (OTA-C) filter design for wireless receivers. It employs a novel adaptive biasing circuit for large-signal linearization that extends the filter's usable signal swing range. An analysis of this linearization technique provides insights into its underlying concepts to assist the design process. The method is demonstrated with the first experimental evaluation of a second-order complex baseband filter prototype having a center frequency of 2 MHz and a bandwidth of 850 KHz. Fabricated in a standard 130nm CMOS technology, the filter prototype measurement results show a gain of 35.1 dB and an image rejection ratio of 39.7 dB while operation from a supply voltage of 0.95 V and consuming 0.13 mA. This design advances the low-power bandpass filter state-of-the-art by having an in-band and out-of-band SFDR of 62 dB and 64 dB respectively due to the use of the large-signal linearization approach.