A Correlation-Based Background Error Estimation Technique for Bandpass Delta–Sigma ADC DACs

This brief presents a background digital-to-analog converter (DAC) error estimation technique for multibit bandpass Delta-Sigma analog-to-digital converters (ΔΣ ADCs). The technique is used to estimate and linearize the intrinsic mismatches of feedback DAC unit elements of ΔΣ ADCs. It consists of three building blocks, namely, a correlation-based error estimation, which utilizes a test signal to estimate DAC unit element gain mis matches; a digital error correction, which corrects the estimated DAC nonlinearities; and a unit establishing background operation. The method has been successfully utilized for lowpass ΔΣ ADCs and is extended here by using an additional bandpass filter to create a modified test signal, which meets the requirements of bandpass Δ modulators. The method restores highly nonlinear systems back to their ideal linearity while requiring only little additional hardware effort and enables the design of linear multibit bandpass ΔΣ modulators.