The design of a low-distortion sigma-delta ADC for WLAN standards

A low-distortion sigma-delta analog-to-digital converter (ADC) for wireless local area network (WLAN) standards is presented. The proposed sigma-delta modulator architecture employs the 4-bit 2^nd order sigma-delta modulator with swing suppression in a 2-2 modified cascaded configuration, which greatly improves the tonal behavior even at 8X over-sampling ratio (OSR). The modulator is designed in 0.18μm CMOS process and operates at 1.8V supply voltage. It achieves a dynamic range of 69.1dB and a spurious free dynamic range (SFDR) of 82.2dB for a 10MHz signal bandwidth, and an oversampling ratio of 8.