A 4.21-μV Offset Voltage and 42-nV/√Hz Input Noise Chopper Operational Amplifier with Dynamic Element Matching

Abstract

This paper presents a high-efficiency operational amplifier (op-amp) used in the readout circuit of micro-sensor. The chopping and dynamic element matching (DEM) techniques are used in the proposed design, which greatly reduce the offset voltage and flicker noise [Formula: see text] noise) of the op-amp. By optimizing the circuit structure, the maximum chopping frequency is increased to 2[Formula: see text]MHz when the offset voltage is less than [Formula: see text][Formula: see text]V. Therefore, the maximum bandwidth of signal processing can be up to 1MHz. The proposed circuit is designed and fabricated using TSMC 0.18-[Formula: see text]m 1P5M CMOS technology. It occupies an area of 0.16[Formula: see text]mm2 and consumes [Formula: see text]A from a 1.8-V supply. When the chopping frequency is 100[Formula: see text]kHz, the input-referred offset voltage is 4.21[Formula: see text][Formula: see text]V and the input-referred noise is 42[Formula: see text]nV[Formula: see text]Hz. It achieves a noise efficiency factor of 7.82 and a power efficiency factor of 110.07.