140–220-GHz DHBT Detectors

This paper discusses
G
-band (140-220 GHz) detectors based on a 250-nm InP-InGaAs-InP double heterojunction bipolar transistor process available from the Teledyne Scientific Company. Two types of detectors are presented-a passive detector where the transistor's base-emitter junction nonlinearity is used, and an active detector, where the transistor transconductance nonlinearity is used for detection. Measurements of transistor noise-power spectrum density at low frequencies is used to model and predict the noise equivalent power (NEP) of the detectors. Analysis of responsivity and noise is presented and compared with measurements. Both configurations are analyzed and compared in terms of noise-voltage, responsivity and NEP. The conclusion that the passive detector offers lower NEP is analyzed and explained.