Abstract: In order to raise the whole count rate of a wedge-strip anode's photon-counting imaging detector, according to the feature of the signal output from the detector, a position readout circuit was designed and developed. This circuit is based on high speed Analog-Digital (A/D) converters and a Field Programmable Gate Array (FPGA) chip. The circuit employs high speed A/D converters with 65 MHz sapling rate to transform the Gaussian pulse analog signal into digital series at every clock period and obtain the peak value of the pulse signal by a FPGA. It has the functions of peak hold module of voltage pulse and NI data collection card in the original circuit. The FPGS processes the received digital series according to certain rules and sends them to the computer by UBS data interface. The developed software can compute the coordinate position of every photon and display them on PC screen according to obtained 3-way data. The design of the circuit hardware and logic control is described in detail in this paper. Experiment results show that the designed circuit can get a 2D image with same position resolution and double count rate compared with the original circuit with peak hold and NI card.

Key words: electronic technique, photon-counting, position readout circuit, analog to digital conversion