Comparative Analysis of the Selected Photoreceiver Input Stages in Terms of Noise

Semiconductor radiation detectors usually use a specific signal conditioning circuit, ensuring the required detection system parameters. This paper details the noise properties of specific input stages in photoreceivers that detect various types of radiation. For this purpose, the popular silicon PIN photodiode (BPW34) and two different types of low-noise operational amplifiers (AD797A and ADA4625-1) were used. In the presented experiments, noise measurements were provided for voltage and transimpedance amplifiers operating in input stages, comparing their noise and bandwidths. This made it possible to obtain results for bipolar junction transistor (BJT)- and field-effect transistor (FET)-based input stages of circuity, cooperating directly with a photodiode. Analyzing the obtained characteristics and considering the photodiode operation mode, it is evident that the transimpedance amplifier and photoconductive mode should be considered a typical first-choice solution. In some cases, the performances, such as bandwidth and noise, may be similar to those of voltage. Nevertheless, the bias method used in TIA and feedback compensation can also affect the resulting output noise spectral characteristics due to the photodiode and other capacitances existing in the circuit. In the case of a high transimpedance, the FET-based op-amps ensure lower output noise than the BJT-based ones due to the significantly lower current noise. The simple radiation detector with two-channel differential TIA was also proposed and tested based on the results obtained.