Direct comparison type FPGA-ADC device based on single carry chain

Abstract

The invention provides a direct comparison type FPGA-ADC device based on a single carry chain, and relates to the technical field of medical imaging equipment. The device comprises a calibration signal generator, a low-pass filter circuit, a comparator, a clock generator, a carry chain time measurement module, a fine time coding circuit, a coarse time counter, a nonlinear correction circuit, a pulse width calculation circuit and the like. The clock generator generates a sampling clock, and the sampling clock is compared with an input analog signal through the FPGA internal comparator after passing through the low-pass filter circuit, thereby obtaining a to-be-measured pulse. The width of the to-be-measured pulse can be approximately proportional to the amplitude of the input analog signal,and analog-to-digital conversion can be completed by measuring the pulse width of the to-be-measured pulse. Based on FPGA chip logic codes and an off-chip simple resistance-capacitance discrete device (a low-pass filter), the ADC with low cost, low power consumption, high integration level and high performance and the 100-megabit magnitude sampling rate can be realized, and the ADC has great significance for a whole detector and even a PET system.

Description

technical field [0001] The invention relates to a SIPM-based PET detector, in particular to a direct comparison FPGA-ADC device based on a single carry chain, which belongs to the technical field of medical imaging equipment. Background technique [0002] At present, the positron emission tomography (PET) system plays an increasingly important role in the detection of early cancer, and the detection device based on the silicon photomultiplier tube (Silicon Photomultiplier, SiPM) is due to its good energy and Temporal resolution and magnetic compatibility are increasingly used in PET systems. The principle of the SiPM-based PET detector is to use the SiPM to convert the high-energy Gamma photons captured by the detector crystal module into low-energy visible light signals through the photoelectric effect and then convert them into analog electrical signals, and use the analog conditioning circuit to amplify the analog electrical signals. Then use the energy measuring device ...

AI Technical Summary

Problems solved by technology

[0003] However, the current energy measurement devices are basically based on commercial ADC chips to achieve analog-to-digital conversion, and then send the obtained digital information into the Field Programmable Logic Gate Array (Field Program Gate Array, FPGA) chip to complete the energy integration algorithm. There are a lot of channels of the converter, and a large number of commercial ADC chips are needed to realize it, which will increase the system cost and cause large power consumption, and severely limit the integration of the electronic system

In other words, its high ADC cost, high power consumption and other defects are not conducive to multi-channel integration

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