Abstract. The effects of photodiode bulk leakage current and amplifier noise on receiver sensitivity are analysed using a model described previously [4]. The sensitivity of a receiver using a PIN photodiode can be greatly improved by employing a high-performance microwave FET in the input stage, to the point where its remaining technical disadvantage in comparison with a silicon APD receiver at 800-900 nm may be offset by economic and operational attractions. In systems operating at the optimum transmission wavelength beyond 1.1 μm, the PIN-FET hybrid receiver may offer better technical performance than an APD receiver.
