Single op‐amp second‐order loop filter for continuous‐time delta–sigma modulators

A second‐order loop filter (LF) that uses a single op‐amp resonator is presented for continuous‐time delta–sigma modulators. The proposed technique improves the power and area efficiency of the LF and enhances the controllability of the transfer function and the resonating condition by providing a new RC network. A second‐order modulator has been designed to confirm the effectiveness of the proposed scheme. Implemented in a 130 nm CMOS, the prototype modulator occupies an active area of 0.098 mm 2 and consumes 5.23 mW power from a 1.2 V supply. It achieves a peak SNDR of 60.95 dB over a 15 MHz signal bandwidth with a sampling frequency of 780 MHz.