An Equivalent Circuit Model for Uni-Traveling-Carrier Photodiode

In this paper, an improved equivalent circuit model for millimeter-wave characterization of the uni-traveling-carrier photodiode (UTC-PD) device is presented, which plays an indispensable role in the improvement of its structure and performance. A de-embedding technique is proposed to extract the original characteristics of UTC-PD, which takes coupling parasitic effects into account. Moreover, we propose a set of characteristic functions according to the equivalent circuit model of UTC-PD and an analytical approach to extract model parameters is then derived based on aforementioned characteristic functions, which is more consistent with the physical meaning of the model and avoids the problem of multi-valued solution using software fitting. A high precision fit between simulated and measured S-parameters can be achieved up to 40 GHz. Therefore, the equivalent circuit model can provide guidance for the design of integrated circuits containing UTC-PD and the study of their matching circuits.