Researchers at the UCLA Department of Electrical & Computer Engineering have developed a millimeter-wave spectrum analyzer that uses a non-linear fast switch to generate a broadband frequency comb local oscillator (LO) with a tunable repetition rate.
Broadband integrated circuits in millimeter-wave and terahertz (THz) frequencies provide low-cost and compact solutions for high-resolution hyper-spectral imaging and molecular spectroscopy. Non-linearity of the direct CMOS THz detectors based on the plasma-wave effect in MOS transistors recovers the power of the millimeter-wave/THz signal for building imaging arrays. However, in order to develop hyper-spectral imaging systems or trace-gas spectrometers, coherent receivers are required to extract the frequency content. Sub-harmonic mixers have been used in to coherently receive the sub-THz signals. High-power LO signals are needed in these mixers to down-convert the received signal to low frequencies and multiple VCOs need to be implemented to cover a wide LO frequency range.
Researchers at UCLA have developed a millimeter-wave spectrum analyzer that uses a non-linear fast switch to generate a broadband frequency comb LO with a tunable repetition rate. A broadband frequency comb with a frequency spacing of frep is used to detect the spectrum of any received signal within the same bandwidth. An NFET is used as a broadband heterodyne plasma-wave detector to down-convert the received tones to distinguishable low frequency tones. The receiver is operated from 30 to 160 GHz, where the maximum frequency is limited by measurement equipment.
The described millimeter-wave spectrum analyzer was tested experimentally.
broadband, millimeter-wave, wireless communication, spectrum analyzer, spectrum sensing, CMOS, hyper-spectral imaging