Submillimeter-wave receiver with a balanced monolithic mixer

Development of terahertz mixers and a study of their characteristics

“…To achieve such values in the terahertz range, the diode capacitance should amount to several femtofarads, the series resistance should be about 10 Ω, and the diode dimensions, about 1 µm. The technological challenges of manufacturing mixers with a submicron Schottky-barrier (SB) window required the necessity to consider the possibility of using earlier design solutions realized in the wavelength ranges near 1.5 and 0.8 mm [2,3] and having demonstrated the best results for their time, as well as some other approaches [4] for creation of terahertz mixers. Before describing some of them in more detail, we emphasize that, as in [3], design was based on using two-port mixers, which did not need an additional diplexer to supply the received radiation and the radiation of the heterodyne oscillator.…”

“…The technological challenges of manufacturing mixers with a submicron Schottky-barrier (SB) window required the necessity to consider the possibility of using earlier design solutions realized in the wavelength ranges near 1.5 and 0.8 mm [2,3] and having demonstrated the best results for their time, as well as some other approaches [4] for creation of terahertz mixers. Before describing some of them in more detail, we emphasize that, as in [3], design was based on using two-port mixers, which did not need an additional diplexer to supply the received radiation and the radiation of the heterodyne oscillator. All the monolithic integrated circuits (MICs) were mounted in waveguides with the corresponding cross sections, which tapered smoothly to the input and heterodyne-oscillator horns with aperture diameters of 2 mm to reduce significantly the losses for coupling with the antenna and heterodyne channels.…”

“…The calibration based on observing the radiation from two matched loads at room temperature and boiling nitrogen temperature, respectively, showed that in the vicinity of 370 GHz, the double-sideband noise temperature T DSB rec of the receiver was 4000 K (in [3], the value of 1750 K was obtained for this frequency). Near 470 and 580 GHz, where the sensitivity maxima would be located, the double-sideband noise temperature of the receiver amounted to 44000 and 50000 K, respectively.…”

“…Balanced mixers with a monolithic integrated circuit, which was manufactured by means of the scale copying of a MIC having shown its advantage [3] and was placed in a circular waveguide of 0.5 mm in diameter, were tested as components of a superheterodyne receiver which had replaceable heterodyne oscillators (OV-65 and OV-80 backward-wave oscillators (BWOs) operated in the ranges 230-380 GHz and 450-650 GHz, respectively) and an intermediate-frequency amplifier (IFA) with the noise temperature T IFA = 60 K in the range 750-850 MHz. The calibration based on observing the radiation from two matched loads at room temperature and boiling nitrogen temperature, respectively, showed that in the vicinity of 370 GHz, the double-sideband noise temperature T DSB rec of the receiver was 4000 K (in [3], the value of 1750 K was obtained for this frequency).…”

“…(the double-sideband noise temperature of the mixer and the conversion loss were calculated in a way similar to that described in [2,3]). In this case, at the first harmonic,…”