High gain-bandwidth differential distributed InP D-HBT driver amplifiers with large (11.3 Vpp) output swing at 40 Gb/s

High-performance and compact 40-Gb/s driver amplifiers were realized in 1.2-μm emitter double-heterojunction InGaAs-InP HBT (D-HBT) technology with a maximum cut-off frequency (f_T) of 150 GHz and a maximum oscillation frequency (f_max) of 200 GHz. Two-stage differential drivers feature a lumped input and fully distributed output stage and deliver a maximum differential output swing of 11.3 V peak-to-peak (V_pp) at 40 Gb/s with less then 350 fs of added rms jitter and rise and fall times of about 7 ps while consuming a total power of 3 W. When biased at a lower output swing of 6.3 V_pp, excellent 40-Gb/s eyes with a 7-ps fall time, 6-ps rise time, and no observable jitter deterioration compared with the input source are obtained at a reduced power consumption of 1.7 W. On-wafer measured differential S-parameters show a differential gain of 25 dB, 50 GHz bandwidth, and input and output reflection below -20 dB from 2 to 45 GHz. The amplifiers´ small die size (1.0×1.7 mm), relatively low power consumption, large output swing, and ability to have dc coupled inputs and outputs enable compact 40-Gb/s optical transmitters with good eye opening for both conventional transmission formats such as nonreturn-to-zero and return-to-zero and alternative formats such as duobinary and differential phase shift keying.