A low-noise low-power highpass sigma-delta analog to digital converter for medical sensor

摘要

A novel analog to digital converter consisting of sigma-delta modulator and chopper-stabilization circuit, which is suitable for converting a small signal such as electrocardiogram since the scheme inherently suppress low-frequency noise such as thermal drift, is presented. This scheme inherently suppress DC offset and thermal drift by chopping the input signal at a half of the sampling frequency and shaping the quantization noise to minimize at the Nyquist frequency. The scheme, namely highpass sigma-delta modulation, is numerically analyzed using the MMTLAB and experimentally verified using a field programmable analog array chip.