GaAs/GaAlAs Heterojunction Bipolar Phototransistor for Monolithic Photoreceiver Operating at 140 Mbit/s

The development of optical transmission calls for sensitive and fast optoelectic transducers. With the advent of optical local area networks, hybrid transducers may no longer be appropriate, and monolithic emitters and receivers will be preferred. In this paper, we report on the first monolithic photoreceiver implemented with GaAs-GaAIAs bipolar devices. One phototransistor and two transistors are integrated, together with four resistors on a 0.5x0.5-mm² GaAs chip. The transimpedance receiver has a bandwidth of 80 MHz. SignaI and noise power measurements indicate that for a digital signal at 140 Mbit/s, the minimum detectable power is 1 µW (-30 dBm).