A 0.9V 0.022mm2 103dB DR Switched-Capacitor Audio Delta-Sigma Modulator Using Input-Referred kT/C Noise Reduction Technique

Switched-capacitor (SC) circuits have been widely used for sampling operation of mixed-signal integrated circuits, especially in CMOS technologies. Using with amplifiers, SC circuits enable the robust implementation of the sampling network with various transfer functions. However, the kT/C noise resulting from the transistors used for switches limits the achievable signal-to-noise ratio (SNR). Therefore, achieving wide dynamic range (DR) requires a large amount of on-chip sampling capacitance. In [1], a continuous-time input stage is employed to achieve the kT/C noise free operation, which leads to considerable power and area reduction. However, the capacitive coupling used at the input will block DC signals and limit the range of suitable applications.