Low-Noise Chopper-Stabilized Multi-Path Operational Amplifier with Nested Miller Compensation for High-Precision Sensors

• Published in: Applied sciences Vol. 10; no. 1; p. 281
• Main Authors: Kim, Jaesung, Kim, Hyungseup, Han, Kwonsang, You, Donggeun, Heo, Hyunwoo, Kwon, Yongsu, Cho, Dong-il “Dan”, Ko, Hyoungho
• Format: Journal Article
• Language: English
• Published: MDPI AG 01.01.2020
• Subjects: chopper stabilization technique; class ab output; low-noise amplifier; multi-path amplifier; noise efficiency factor (nef); notch; ripple reduction loop (rrl)
• ISSN: 2076-3417; 2076-3417
• DOI: 10.3390/app10010281

This paper presents a low-noise multi-path operational amplifier for high-precision sensors. A chopper stabilization technique is applied to the amplifier to remove offset and flicker noise. A ripple reduction loop (RRL) is designed to remove the ripple generated in the process of up-modulating the flicker noise and offset. To cancel the notch in the overall transfer function due to the RRL operation, a multi-path architecture using both a low-frequency path (LFP) and high-frequency path (HFP) is implemented. The low frequency path amplifier is implemented using the chopper technique and the RRL. In the high-frequency path amplifier, a class-AB output stage is implemented to improve the power efficiency. The transfer functions of the LFP and HFP induce a first-order frequency response in the system through nested Miller compensation. The low-noise multi-path amplifier was fabricated using a 0.18 µm 1P6M complementary metal-oxide-semiconductor (CMOS) process. The power consumption of the proposed low-noise operational amplifier is 0.174 mW with a 1.8 V supply and an active area of 1.18 mm2. The proposed low-noise amplifier has a unit gain bandwidth (UGBW) of 3.16 MHz, an input referred noise of 11.8 nV/√Hz, and a noise efficiency factor (NEF) of 4.46.