Adaptive Digital Calibration and Decimation Filter Design for Delta Sigma ADC

Abstract

Analog to digital converters (ADC) and digital to analog converters (DAC) are critical components of mixed signal systems, as they provide the interface between analog and digital domains. Delta sigma ADCs are widely used due to their high resolution as compared to other ADCs. The techniques of noise shaping and oversampling are utilized in modulator to achieve such high res- olution. In recent times, numerous enhancement techniques are presented to further improve the resolution of delta sigma ADC. In this research thesis, adaptive ltering technique, adaptive line enhancer is used to improve the signal to noise ratio (SNR) of Delta Sigma ADC. Adaptive line enhancer extracts the estimate of signal of interest from noisy input signal by updat- ing lter coe cients using least mean square (LMS) algorithm. Design and implementation of ALE for delta sigma ADC is presented. The implemen- tation of ALE after modulator and after decimation lter is analyzed. ALE employed after decimation lter suppresses noise from band of interest thus improving SNR which is directly related to resolution of ADC. The simu- lation results have shown around 5 dB improvement in SNR. Comparison of nite impulse response (FIR) and cascaded integrator comb (CIC) filter based decimation fi ltering is also presented.