A chopper-stabilized high-pass Delta–Sigma Modulator with reduced chopper charge injection

In this paper, a chopper-stabilized high-pass Delta–Sigma Modulator (DSM) is reported with experimental results. A new circuit technique to suppress the residual offset caused by the chopper switch charge injection is proposed. Enabled by an amplifier sharing architecture, the technique diverts the error charge generated by the critical chopper to the second stage of the modulator such that the resulted error becomes first-order high-pass shaped. Fabricated in a 0.18 μm CMOS technology, the 2nd-order DSM realizes 82 dB dynamic range over a 1 kHz bandwidth while consuming 144 μW from a 1.8 V supply. The offset is 403 μV and the flicker noise is invisible in the measured output spectrum down to 4 Hz. The core area of the chip is 0.16 mm2.