A 4th order Gm-C filter with 10MHz bandwidth and 39dBm IIP3 in 65nm CMOS

Abstract

Gm-C filters suffer from limited dynamic range due to a trade-off between noise and linearity in OTA design. This paper therefore presents a filter with a linearization technique to break this trade-off. This technique is demonstrated by a low power 4th order 10MHz Butterworth Gm-C low pass filter. The filter was implemented in 65nm CMOS technology with a core area of 0.19mm2 and a total current consumption of 3.5mA from a 1.2V supply. The measured input referred noise is 31nV/√Hz, the maximum in-band IIP3 is 39dBm, the out-of-band IIP3 is 34dBm, and the compression point is 8.2dBm.