An Ultra-broadband Low-Noise Distributed Amplifier in InP DHBT Technology

This paper reports an ultra-wideband low-noise amplifier in a transferred-substrate InP DHBT technology. The wideband characteristics are obtained by using a distributed topology with cascode unit cells. Each unit cell consists of two cascode-connected transistors with 500 nm emitter length and an ft/fmax of ~350/400 GHz respectively. Due to optimum line-impedance matching, low common-base transistor's capacitance, and low collector-current operation, the circuit also exhibits a low noise figure. The measured circuit shows a bandwidth of 40...185 GHz with a noise figure of 8 dB in the frequency range 75...105 GHz. Moreover, this circuit demonstrates the widest 3-dB bandwidth operation among all reported single stage amplifiers with cascode configuration.