Analysis and design of a high performance Infrared detector readout circuit

This paper presents a high performance readout circuit for Infrared detector. The circuit is composed of capacitor trans-impedance amplifier (CTIA) and correlation double sampling (CDS) circuit. The CTIA structure is used to convert the photo-current into voltage, and could obviously improve the readout accuracy of weak current signal. And the CDS structure is used to reduce the fixed pattern noise (FPN) of CTIA. Thus, the signal to noise ratio (SNR) of the designed readout circuit is improved. Meanwhile the small signal models of CTIA and CDS are established, and the converting accuracy and speed are fully discussed. The final chip is fabricated with Chartered 0.35 um standard CMOS process, and occupies a 45 ¿m×400 ¿m area. Under the condition that the power supply is 3.3 V, operation of the fabricated chip is verified, and the output dynamic range is measured as 0.3 to 2.48 V. Testing results show that the linearity of CTIA is 99%, and that the readout accuracy is 10-bit, while the detecting current varies from 20 pA to 10 nA.