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 photodiode 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.