A 40-Gb/s preamplifier using AlGaAs/InGaAs HBT's with regrown base contacts

A preamplifier for 40-Gb/s optical transmission systems incorporating AlGaA s/InGaAs heterojunction bipolar transistors (HBT's) with p(+) regrown extri nsic base layers is described. The HBT's have a heavily doped regrown p(+)- GaAs layer in the extrinsic base regions and a thin graded InGaAs strained layer for the intrinsic base. Their measured peak f(max) is above 200 GHz, The developed preamplifier provides a bandwidth of 38.4 GHz and a transimpe dance gain of 41.1 dB Ohm. Moreover, the frequency response as an optical r eceiver has a bandwidth of 32 GHz, These characteristics make the preamplif ier suitable for use in a 10-Gb/s optical receiver. These results show that AlGaAs/InGaAs HBT's with p(+) regrown extrinsic base layers are very promi sing for use in 40-Gb/s optical transmission systems.