Low Cost, Single-ended, 2M Ohm Input Impedance 98dB Stereo Audio A/D Converter With a Novel Front-end Sampling Network

A single-ended multibit delta-sigma stereo audio ADC is presented. A 3rd-order single-loop 10-level feed forward delta-sigma modulator is implemented. A feed forward stage and a rough/fine input sampling scheme combined with a novel front-end sampling network allows wide dynamic range at lower power, smaller die size and larger than 2M ohm input impedance. A second order mismatch shaper removes any nonlinearity or tones caused by element mismatch in the feedback DAC. It achieves 98dB dynamic range and 105dB THD with 0.5k ohm of source impedance while dissipating 60mW@5V. The chip occupies 2-mm² area in 0.25mum-process and fits into a tiny 10-pin TSSOP package