Wideband active matching of terahertz envelope detectors

Impedance matching of zero-bias millimeter-wave/THz diodes is examined in the context of THz communications receivers. Specifically, we present an active matching circuit that can realize Gb/s bandwidth performance for a 230GHz carrier frequency envelope detector. The active circuit consists of two transistor stages preceded by a 3
^rd
order L/C matching network. Using a cascode stage followed by an emitter-follower, the baseband output impedance of THz diodes is matched to a standard 50Ω port of subsequent amplifier stage. Matched signal bandwidths as much as 1.2GHz can be achieved using this simple configuration. Examples demonstrate the performance and the benefits of the proposed active matching for high data rate THz receivers.