New signal conditioning architecture for optimal a/D conversion in digital spectroscopy setups

Abstract

By exploiting some interesting properties of feedback loops including an analog-to-digital converter (ADC) and a digital-to-analog converter (DAC), it is possible to perform filtering action on both signal and noise in a mixed digital-analog realm, similar to the well-known sigma-delta ADC. In particular, we present a signal conditioning architecture based on this loop, which optimizes the analog-to-digital conversion operation in a high-resolution digital spectrometer. Elimination of pile-up at the ADC input, which minimizes the probability of its saturation as well as minimization of alias effects are achieved with no significant hardware burden and no measurement resolution loss. The filtering action inherent in the loop is used to obtain pole-zero cancellation, to improve the input signal rate, to reduce the effects of quantization noise by pushing it out-of-band, and to enhance the linearity of the converter. The technique has been implemented and validated.