225-280 GHz Receiver for Rotational Spectroscopy

A fully integrated CMOS receiver for mm-wave rotational spectroscopy is demonstrated. The receiver consists of a sub-harmonic mixer based receiving front-end which down-converts 225-280 GHz RF input to 20 GHz intermediate frequency, a 20-GHz AM demodulator followed by a baseband buffer amplifier, and an 122-139 GHz local oscillator chain which is comprised of a frequency quadrupler and a driver amplifier. The receiver exhibits responsivity of 400-1200 kV/W and noise equivalent power of 0.4 to 1.2 pW/root Hz from 225 to 280 GHz. Detection of ethanol, propionitrile (EtCN), acetonitrile (CH3CN) and acetone in a mixture is demonstrated using the receiver in a rotational spectrometer setup. This is the first demonstration that a CMOS receiver can be used for rotational spectroscopy and that a CMOS circuit can support an existing application at frequencies above 200 GHz.