This paper presents the design of operational transconductance amplifier (OTA) as a core building block of the
capacitive transimpedance amplifier (CTIA) for the implementation of infrared readout circuit on VLSI chips. The OTA has a two-stage amplifier which achieves low power and low noise. In addition, a voltage reference is designed for biasing the
amplifier. Low power dissipation of the OTA is achieved by using of a supply voltage of 1.2 V and transistors operating in the subthreshold region. The designed OTA, built in standard 0.13 μm CMOS technology, dissipates 3.2 μW of power with input referred noise of 52.1 nV/√Hz@1KHz. Also, the OTA has a common mode rejection ratio of 81 dB and input offset voltage of 5.089 μV. This is accomplished by the efficient sizing of the used transistors together with a compensation capacitor.