A 410 μW, 70 dB SNR high performance analog front-end for portable audio application

This paper describes an analog front-end (AFE) intended for portable audio application, which operates at 1 V and consumes only 410 μW. The AFE consists of a 30 dB-gain programmable gain amplifier (PGA) and a 2nd-order 3-bit sigma-delta modulator. The PGA with single input and on-chip common-mode bias voltage shows good noise-reduction performance. The modulator makes use of data weighted averaging to reduce the linearity requirements of the digital-to-analog converter in the feedback loop. The AFE is implemented in the SMIC 0.13 μm 1P8M CMOS process. The measurement results show that in a 1 V power supply, at 200 mV_p-p, between 100 Hz and 20 kHz, the maximal signal-to-noise ratio is 70 dB, and the total power is 410 μW. (semiconductor integrated circuits)