A low-power BiCMOS switched-capacitor filter for audio codecapplications

A fully integrated fourth-order filter embedded in a complete 16-b oversampled D/A converter to be used in an audio stereo codec is presented. The possible noise and distortion sources have been accurately evaluated in the design and their contributions have been properly limited. This allows the reduction of the power consumption while satisfying the application requirements. The filter is realized in 0.7-μm BiCMOS technology with an active area of about 1.3 mm² . A total harmonic distortion (THD) of -75 dB for a full scale input signal and an SNR of 96 dB have been achieved. The power consumption of the filter has been maintained within about 40 mW from a single 5-V supply voltage