A CMOS Fourth-order Delta-sigma Modulator with a Single Reconfigurable Fully Differential Amplifier

초록

This paper describes a CMOS 4th-order delta-sigma modulator with only one amplifier for the application of bio signal processing. The proposed modulator employed only a single reconfigurable fully differential amplifier which becomes either the folded-cascode amplifier or two stage operational one, depending on the load capacitance. The modulator is implemented with 180 nm CMOS standard process. The measurement results demonstrate the peak SNDR of 72.8 dB and the ENOB of 11.8 bits with an input signal frequency of 250 Hz, a sampling frequency of 256 kHz, an input signal bandwidth of 1 kHz, and an oversampling rate of 128. The power dissipated is measured to be 356 mu W (analog power of 302 mu W and digital power of 54 mu W). FOM1 and FOM2 are calculated to be 49.6 pJ/step and 155 dB, respectively.

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