A tunable Gm-C polyphase filter with high linearity and automatic frequency calibration

Abstract

In this paper, a new CMOS Gm-C poly-phase filter used in Low-IF receiver is presented. As the requirements of multi-model and multi-band determine the frequency tunability, a master-slave transconductance control circuit is designed. Besides, a low power consumption automatic frequency calibrate circuit is used to resist the PVT. A novel 4^th order poly-phase filter is designed in SMIC 0.18 µm standard CMOS process. Consuming 1.1 mA from a 1.8 V voltage, simlution results show that the filter has a tunability of center frequency from 150 kHz to 500 kHz and bandwith from 100 kHz to 900 kHz independently. Meanwhile, the polyphase filter achieves a IIP3 above 18 dBm.