245 GHz SiGe Transmitter Array for Gas Spectroscopy

A 245 GHz transmitter (TX) array with an integrated antenna-array for a gas spectroscopy system has been realized, which consists of a push-push VCO with a 1/64 frequency divider, power amplifiers, frequency doublers, and on-chip antennas with localized backside etching. The TX-frequency is tunable in the range from 238 GHz to 252 GHz. The TX-array is fabricated in 0.13 µm SiGe:C BiCMOS technology with fT/fmax of 300GHz/500GHz. Its estimated output power is 7 dBm at 245 GHz, and the EIRP reaches 18 dBm at 245 GHz. The 245 GHz spectroscopy system includes a TX and a receiver in SiGe. The sensitivity of this spectroscopy system is demonstrated by the high-resolution absorption spectrum of methanol and will be increased further by this TX-array.