LAUSR

This paper presents a low noise and residual offset chopper-stabilized precision instrumentation amplifier intended for use in measurement systems. Conventional chopper-stabilized instrumentation amplifier introduces a necessary trade-off between the low residual offset and noise provided by a high-transconductance input stage and the resulting high residual ripple. However, to achieve low noise and residual offset, the proposed chopper-stabilized instrumentation amplifier employs a relatively high-transconductance input stage to reduce the offset and 1/f noise, and uses a switched-capacitor notch filter as low-pass filter to filter out the chopper ripple caused by the up-modulated offset and 1/f noise, and introduces a ripple reduction loop (RRL) to reduce the resulting high residual ripple amplitude. The complete chopper-stabilized instrumentation amplifier is implemented in a standard 0.18 μm CMOS technology. It occupies an area of approximately 1.2 mm2 and consumes 75 μA current from a 1.6 V supply voltage. The input-referred noise power spectral density is 20 nV/√Hz and its residual offset is less than 4 μV. The RRL achieves a ripple rejection ratio of 26 dB.