Nonlinearities of High-Speed p-i-n Photodiodes and MUTC Photodiodes

The linearity, the RF output power, and the bandwidth for p-i-n photodiodes (PDs) and modified uni-traveling carrier (MUTC) PDs are analyzed for a variation of bias voltage and optical input power. Based on an equivalent circuit, equations for analytic calculation of these PD parameters are derived. Good agreement between the measurements and the calculated results of a p-i-n PD and a MUTC PD could be observed for frequencies up to 135 GHz. As a result, the linearity is improved and its photocurrent dependence can be reduced when the bandwidth of the PD is limited by the RC time constant.