A Widely Tunable Active-RC Complex Filter for Multi-Mode Wireless Receivers with Automatic Frequency Tuning

Abstract

A 5th-order Chebyshev active-RC filter has been implemented in TSMC 0.13μ CMOS technology. With the feature of multi-mode, it has 8 different bandwidth modes including 6 Real Low-pass modes and 2 Complex band-pass modes for wireless sensor network applications. Combined with a special kind of Miller compensation method, the OTA’s stability is observably improved. Also, to eliminate the effect of temperature and process variation, an automatic frequency tuning scheme is applied. The filter measures a 0dB gain and 0.9 dB ripple in passband. It also measures an input-referred noise of and in-band-IIP3 of 25dBm while consuming 15mA current from 1.3V supply. The tuning circuit has a precision of 2% and covers a range of 30%.