Design Of Readout Integrated Circuit Based On 2×2 Pixel In Photodiode Array

Pulsed beam imaging technology has been widely used in industrial control, medical testing, automotive electronics, deep space exploration, aerospace and other fields, and the readout circuit is the core of the pulse beam imaging system, its performance determines the quality of imaging. Because of the photodiode array has been widely used in pulsed beam imaging, The topic is on the background of CMOS readout integrated circuit applied to the photodiode array, to expand the research on hotspot about 2×2 pixel readout circuit,with good looking and practical value.Photodiodes are the key components to probe pulse beam, this paper analyzes the basic principle of the photodiode and the reading circuit, establishes an equivalent model of photodiode detector, meanwhile, compare and analysis the common basic structure of the reading circuit. In order to solve the key technical problems of pixel wide output voltage swing and high linearity, the traditional circuit structure has been improved, and a method of the current sub-file and the first address of the active output has been proposed. On this basis, the pre-amplifier, the structure of the constant-gain amplifier, the output of the driver stage amplifier modules and pixel address mapping circuit is given. based on a consideration of speed and area, the pre-amplifier adopt a negative feedback transimpedance resistor amplifier configuration, through changing feedback resistor size,to achieve variable gain control. To solve the output of multiple address problem, a new method of initial address to output actively is proposed. Based on power and speed considerations, the address coding circuit and address mapping circuit use a simple combination logic circuit. for the 2×2 pixels multi-channel output voltage reading problems,a four-channel voltage channel selection circuit implemented by the transfer gate switch in parallel is designed.This paper is based on SMIC 0.18?m 1P6 M CMOS process to complete each function module of the 2×2 pixel readout integrated circuit., and verify the functions withcadence respectively; then in the condition of the amplitude range of 1uA~100uA, the pulse width of 100 ns, pulse interval period of 500 ns pulse photocurrent signal, based on the size of 4×4 photodiode array, simulation and verification about the readout integrated circuit of the 2×2 pixel is completed, non-linear output voltage error is less than ? 3.5%, the cell consumes 3.672 mW, to achieve the desired objectives, at the same time the first address outputing accurately, thus having verified the reliability of the circuit functions.