A Large-Signal Millimeter-wave InP/GaInAs Phototransistor Model: Method of Parameters Extraction and Maximum Gain Investigation

Abstract

A large signal opto-microwave modeling technique is developed for an InP/GaInAs heterojunction bipolar phototransistor. The DC and RF parameters as well as the optical parameters extraction methods are described. Then an investigation of the maximum available gain is made using three-port considerations to determine the optimal load impedances. Opto-microwave Sparameters and an opto-microwave gain describing the transfer from the optical input to the electrical output of the phototransistor at millimeter-wave frequencies are defined. This study demonstrates the importance of the base load impedance on the opto-microwave transfer from the optical input to the collector output of the InP/GaInAs heterojunction bipolar phototransistor, and therefore on the phototransistor responsivity.

SiGe heterojunction bipolar phototransistor for optics–microwaves interfacing

“…Static measurement of the photocurrent I PH was performed in photodiode mode (V be ¼ 0) depending on the optical power P at the fiber end (Fig. Due to the internal structure of the phototransistor (directly derived from a foundry transistor) and its optimization in transition frequency, no gain was observed in the phototransistor mode compared to the photodiode mode, as in [5,10,11]. The characteristic is rather linear with a slight saturation effect at high illumination.…”

“…In a previous experiment, we had achieved a higher efficiency ( R = 0.15 A/W) with a sharper fiber end. Due to the internal structure of the phototransistor (directly derived from a foundry transistor) and its optimization in transition frequency, no gain was observed in the phototransistor mode compared to the photodiode mode, as in [5, 10, 11]. But our purpose was to use the phototransistor as a tunable oscillator, not as amplifier.…”