180-GHz Pulsed CMOS Transmitter for Molecular Sensing

The performance of a CMOS transmitter designed for planetary science in situ molecular sensing applications having an operational bandwidth of 180-190 GHz and peak output power of 0.6 mW (-2.22 dBm) is evaluated with a series of spectroscopic-based experimental trials. Continuous wave frequency modulated absorption schemes are exploited to probe the Doppler and sub-Doppler lineshape profiles of the water rotational transition at 183.310 GHz. These results demonstrate the tuning finesse and phase-noise characteristics of the integrated circuit embedded phase lock loop used to generate coherent mm-wave radiation are sufficient for high-precision molecular spectroscopy applications. A description of the pulse modulator designed into the CMOS circuitry allowing for implementation of sensitive emission-based Fourier transform detection schemes is provided with performance characterized for spectroscopically relevant pulse durations (40-500 ns). Results are accompanied by a spectral analysis of the transmitter pulse signal leakage, where the total isolation is measured to be 22 dB. The first emission-based molecular detections obtained with this source are presented demonstrating viability for this transmitter to be incorporated into future planned resonant cavity enhanced in situ molecular sensing systems.

Automated summary

The performance of a CMOS transmitter designed for planetary science in situ molecular sensing applications, with an operational bandwidth of 180-190 GHz and peak output power of 0.6 mW, has been evaluated through spectroscopic-based experimental trials. The results demonstrate the suitability of the transmitter for high-precision molecular spectroscopy applications, showcasing the tuning finesse and phase-noise characteristics of the integrated circuit embedded phase lock loop. Additionally, the design and performance of a pulse modulator in the CMOS circuitry for sensitive emission-based Fourier transform detection schemes are described and characterized.