A low power delta sigma CT modulator for biomedical application

Abstract

Delta Sigma (AE) ADCs are commonly used in biomedical application due to over-sampling technique and noise shaping. A low power 1st order AE was designed in standard 180nm CMOS technology using cadence virtuoso tool. The modulator was designed with a supply voltage of 1.8V, input frequency of 50 KHz. The AE modulator provides the advantage of low power; eliminate the use anti-aliasing filter for reconstruction of input signal and due to over-sampling highly immune to noise outside the frequency band of operation. A two stage op-amp with a gain of 68dB is the basic building block of modulator. The modulator designed with two stage op-amp, achieve an OSR of 256; SNR of 31.86dB; sampling frequency of 2MHz; power of 785μW.