A 107.4 dB SNR Multi-Bit Sigma Delta ADC With 1-PPM THD at $-$0.12 dB From Full Scale Input

Abstract

A second order sigma delta modulator (SDM) with a 5-bit quantizer has been presented using several novel techniques: simplified DAC arrays for easy implementation, high-order truncation noise shaping for increased tolerance to analog imperfections, and an extended dynamic range for a maximum input signal swing of up to -0.12 dBFS (Full Scale). With truncation filters and a pseudo SDM in the DSP, the truncation and saturation errors are compensated through the DAC arrays and the DSP. The design, fabricated in a 0.18 mum dual gate oxide (DGO) process obtains a signal-to-noise-and-distortion ratio (SNDR) of 105.9 dB and a dynamic range (DR) of 107.4 dB with 31.25-KHz bandwidth at an 8-MHz sampling frequency and a power consumption of 14.7 mW.