Silicon-based high-power traveling wave photodetector with inductive gain peaking

We demonstrate Ge/Si high-power and high-speed distributed traveling wave photodetectors (TWPD) by using the inductive gain peaking technique. Input terminals of TW electrodes are open to enhance RF output efficiencies to output loads. Furthermore, optimized on-chip spiral inductors are incorporated at output terminals of TW electrodes to alleviate bandwidth degradations caused by the absences of matching impedances. A comprehensive equivalent circuit model is developed to calculate the frequency response of this scheme. It is used to optimize the design, and then is validated by measurement results. After inducing on-chip inductors, the bandwidths of 4-stage and 8-stage TWPDs are improved from 32 to 44 GHz and 16 to 24 GHz, respectively. Maximum RF output powers of 4-stage and 8-stage TWPDs with on-chip inductors are measured to be 5.7 dBm and 9.4 dBm at 20 GHz, respectively.