A 0.6‐V, 61‐dB DR Fourth‐Order Low‐Pass Filter Using Folded Single‐Branch Biquads

ABSTRACT This paper proposes a novel, compact, and energy‐efficient biquad which is derived from a folded single‐branch transistorized ‐C structure. The biquad has a small number of active devices stacked between and GND rails and hence can be used satisfactorily in a low‐voltage environment. The filter also inherits the benefits of folding in the circuit which makes the tuning of the filter easier and power independent. A fourth‐order low‐pass filter is used as a vehicle to illustrate the performance of the proposed biquad. The fully differential version of the filter is designed in 65‐nm CMOS technology, operates with a supply voltage of 0.6 V, is biased with a current of 100 nA, has a 3‐dB bandwidth of 15 kHz, and shows a dynamic range as high as 61 dB. The postlayout simulations along with FOM numbers show the superior performance of the filter.