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The first monolithic integrated photodetector-preamplifier implemented with GaAs/GaAlAs heterojunction phototransistor and transistors has been fabricated and tested. This photoreceiver has been designed for local networks of optical transmission links operating at 0.85 Â¿m wavelength with multimode fibres. A heterojunction phototransistor (HPT), two heterojunction bipolar transistors (HBTs) and four resistors are integrated in a 0.5 Ã 0.5 mm2 GaAs chip. The photoreceiver with a 26 kÂ¿ external feedback resistor has a bandwidth of 80 MHz with a transimpedance gain of 7000 V/A. The noise measurements indicate that a minimum detectable power of Â¿30 dBm is obtained at 140 Mbit/s for an error rate of 10Â¿9.