Low dc power high-gain bandwidth product InAlAs/InGaAs-InP HBT direct-coupled amplifiers

Here we report on a low dc power and voltage operated InAlAs/InGaAs-InP HBT direct-coupled amplifier which achieves a record Gain-Bandwidth-Product per dc power figure-of-merit (GBP/P/sub dc/) of 3.66 GHz/mW. It is a 44% improvement over previous state-of-the-art HBT and BJT amplifiers based on InP, GaAs, or Si-Ge materials. The amplifier consists of a 2-stage direct-coupled design based on low bandgap InAlAs/InGaAs HBTs with f/sub T/´s and f/sub max/´s of 80 GHz and 200 GHz, respectively. Self-biased from a 3 V supply, the amplifier obtains 15.1 dB gain with a 22 GHz bandwidth while consuming only 34.2 mW of dc power. Biased at 5 V and 23.4 mA, a gain of 19.3 dB and a bandwidth of 25 GHz was achieved with a corresponding open circuit transimpedance of 59.5 dB-/spl Omega/ (944 /spl Omega/) and 25 GHz. Effective 50 /spl Omega/ output loaded transimpedance is 52.7 dB-/spl Omega/ with a GHz bandwidth. The effective transimpedance bandwidth-product is 10.3 THz-/spl Omega/ and is 21% higher than the previous record of 8.5 THz-/spl Omega/ for an AlGaAs/GaAs HBT which consumes more than twice the dc power. This work illustrates the high gain-bandwidth and speed performance which InAlAs/InGaAs HBTs can achieve with very little dc power and suggests great potential for future high data rate IC applications such as optical-electronic communications.