TRANSIMPEDANCE BANDWIDTH PERFORMANCE OF AN HBT LOSS-COMPENSATED COPLANAR WAVE-GUIDE DISTRIBUTED-AMPLIFIER

The authors report the results of a coplanar waveguide loss-compensate d GaAs HBT distributed amplifier which achieves 48dB Omega (251 Omega) with an upper bandwidth response of 19.3GHz while consuming only 75mW of DC power. The corresponding gain is 8.2dB with a 19.5GHz upper fre quency band edge. When biased for maximum gain-bandwidth product, the amplifier dissipates 117mW of DC power and achieves 14.5dB gain with a 16.5GHz bandwidth, and a corresponding transimpedance of 55dB Omega ( 562 Omega) with a 14.4GHz bandwidth. The resulting transimpedance-band width product is 8.1THz Omega which is about a factor of 2 greater tha n previously reported conventional HBT-based direct-coupled topologies when normalised to HBT device cut-off frequency, f(T). These results suggest that the HBT-based distributed amplifier approach has performa nce advantages for high data rate (greater than or equal to 20Gbit/s) optical communication systems.