78 dB SNR multibit continuous-time delta-sigma ADC for readout of CdZnTe detector arrays

Beside the traditional signal processing channel for radiation detector arrays based on multiple analog filter stages, a new direct analog to digital conversion strategy is presented in this paper. The main building block of the new channel topology is a continuous-time analog to digital converter. This paper presents the design and implementation of a 78 dB SNR multibit continuous-time delta-sigma ADC. Such ADC is dedicated to the readout of CdZnTe detector arrays at the bandwidth of 625 kHz. This ADC offers the possibility to move most signal processing steps like pulse shaping, energy detection and timing analysis into the digital domain. The die area and power consumption can be reduced by using digital filtering and advanced signal processing algorithmen. The delta-sigma ADC has been designed in a 180 nm 1P6M CMOS technology. The circuit consumes 3.8 mW from 1.8 Volt supply.