A Wideband Ultra-Low Current Noise Transimpedance Amplifier for Ultrafast Wideband THz Communication

This work reports a wideband transimpedance amplifier MMIC with ultra-low input referred noise current. Being based on transferred substrate InP DHBT process, this work achieves a significant leap forward for ultra-low noise transimpedance amplifier design particularly in HBT based processes, in which, low noise characteristic is fundamentally challenging to achieve. Using a low bias current for amplification, the noise current is kept low. As a result, the amplification is achieved without compromising the noise current performance of the circuit. A 3-dB bandwidth from DC to 10 GHz was achieved with a transimpedance gain of beyond 50 dB $\Omega$ with a measured input referred noise current density of 3 $pA /\surd{Hz}$. To the authors best knowledge, this is the lowest reported input-referred noise current density for InP DHBT based TIA, covering such wide bandwidth.