Optimization of 4T Pixel Structure BiCMOS Detectors using y-parameter Representation

This paper introduces a mathematical relation between ac performance of the four-transistor (4T) pixel structure detector, which can be used to develop optimised detectors pre-manufacturing. The input to this model is the photon-generated current and the output is a voltage signal derived using small-signal analysis with y-parameter representation to accommodate feedback. The proposed methodology used to develop this model will show the ac performance of 4T pixel structure detectors using process-dependent and process-independent parameters. A 0.35 µm SiGe BiCMOS process's parameters were inserted together with reasonable process-independent parameters and simulation results were obtained. Two different configurations were used in this work. Simulation results are presented where the aspect ratio of the MOSFETs, bias voltage and temperature are varied. Using this work, detector designers can select the desired transresistance gain and then calculate the required process-dependent and process-independent parameters. Since many parameters are applicable, it is proposed that a set of parameters of one integrated circuit process be inserted (fixed) and then process-independent parameters can be calculated by the designer.