Abstract
Broad band amplifiers with two Darlington feedback topologies, namely resistive biased and mirror biased, have been designed, fabricated and characterized. The HBT layers used for amplifiers were grown by MBE. To reduce the knee voltage and increase the breakdown voltage of the devices, graded base-emitter junction and low-doped, thick collector have been employed. The fabricated amplifiers have achieved 10.95dB gain with 25.5GHz bandwidth at DC power consumption of only 34.7mW. State-of-art Gain-Bandwidth-Products per dc power were achieved for both amplifiers (≥2.60GHz/mW). The fabricated amplifiers also demonstrated moderate output power (8.3 dBm) ar 10 GHz with a low DC power consumption of only 40mW.