GAAS-FET TRANSIMPEDANCE FRONT-END DESIGN FOR A WIDEBAND OPTICAL RECEIVER

A GaAs f.e.t. transimpedance front-end amplifier was built and operated as part of a regenerator at 274 Mb/s. The noise characteristics were optimised for operation with a Ge photo-diode at 1·32 µm, but were measured at 0·82 µm to compare Si and Ge photodiodes. The amplifier input capacitance was 3·2 pF with the Si p-i-n diode and 4·6 pF with the Ge diode. At 0·82 µm, we measured a sensitivity for 10−9 error rate of about — 35 dBm with the Si diode and — 32 dBm with the Ge diode. We predict a sensitivity of — 34 dBm at 1·32 µm. © 1979, The Institution of Electrical Engineers. All rights reserved.