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 (Formula presented.) -C structure. The biquad has a small number of active devices stacked between (Formula presented.) 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 (Formula presented.) 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. © 2025 John Wiley & Sons Ltd.