X-ray CCD reading system based on discrete time incremental model sigma delta ADC

Abstract

The invention relates to a low-power-consumption and low-noise X-ray CCD reading system based on a discrete time incremental model sigma delta ADC. The X-ray CCD reading system is composed of a front-end reading circuit, a digital control unit and the discrete time incremental model sigma delta ADC, the front-end reading circuit provides gains and adjusts input signals to the dynamic range of the ADC, the discrete time incremental model sigma delta ADC carries out analog-digital conversion on the signals, and the digital control unit can adjust the gains of a front-end amplifier, change the height of the front-end output floating level and adjust a time window of an ADC sample in a forward and backward mode. The discrete time incremental model sigma delta ADC is provided with two passages, each passage is composed of a pre-modulator, an incremental model sigma delta modulator and a downsampling filter, and quantization of CCD signals is realized through a special comb-shaped filter of a truncation coefficient. When the X-ray CCD reading system works under power voltage 3.3 V and the reading speed is 100 kHz, the accuracy can reach 10-11 bits, the equivalent reading noise is smaller than 10 electrons, and the requirements of actual science research and application can be met.

Description

technical field [0001] The invention belongs to the technical field of integrated circuit design, and in particular relates to an X-ray CCD readout system based on an incremental ΣΔADC. technical background [0002] X-ray CCD cameras have gradually become the mainstream detectors used in X-ray astronomical telescopes in recent years. X-ray CCD has very high energy resolution and angular resolution. In order to meet the requirements of high precision and low noise, the traditional X-ray CCD readout system is usually composed of discrete components, but the weight and power consumption of the readout system composed of discrete components are very large, which greatly increases the cost of rocket launch. cost. In addition, due to the low readout rate of the traditional readout system, it takes several seconds or even longer to read out one frame of image signals on the entire CCD plane, resulting in the time resolution of the CCD readout system being insufficient to meet the...

AI Technical Summary

Problems solved by technology

However, the traditional ΣΔADC requires a very complex digital filter, the response time of the digital filter is very long, and there is no one-to-one correspondence between the digital output and the analog input, so it cannot be applied to image signal readout applications

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