SUMMARY
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.
BACKGROUND
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.
INNOVATION
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.
POTENTIAL APPLICATIONS
ADVANTAGES
STATE OF DEVELOPMENT
The described millimeter-wave spectrum analyzer was tested experimentally.