Debabani Choudhury

A 200 GHz tripler using a single barrier varactor

The authors present results for a tripler to 200 GHz using a single barrier varactor (SBV). The performance of the tripler, over an output frequency range from 186 to 207 GHz, has been measured in a crossed waveguide mount. The theoretical performance of the device and the tripler mount have been calculated using large signal analysis. An overall efficiency of 2% was achieved with efficiency at the device of above 5%. A comparison of theoretical and measured results and a discussion of various losses in the mount and the varactor are also presented. >

A novel split-waveguide mount design for millimeter- and submillimeter-wave frequency multipliers and harmonic mixers

A split-waveguide mount for millimeter- and submillimeter-wave frequency multipliers and harmonic mixers is presented. It consists of only two pieces, block halves, which are mirror images of each other. The mount provides parallel and series impedance tuning with two sliding backshorts at both the input and output frequencies while utilizing E-plane arms to provide an in-line waveguide input and output. Its fabrication is much easier than that of a traditional multifrequency waveguide mount. Waveguide losses are minimized by a very compact design with very short input and output waveguides. This mount is especially well suited for planar diodes used with microstrip or suspended stripline RF filters.<<ETX>>

Subharmonic mixer with planar Schottky diodes in a novel split-block at 200-240 GHz

A broadband subharmonic mixer utilizing a planar antiparallel Schottky barrier diode pair has been developed for 220 GHz. The mixer is based on a novel split-waveguide block design consisting of only two central pieces and two tuner drivers which provide series and parallel tuning elements at both the local oscillator and signal frequency. The single sideband noise temperature is just below 2000 K from 210-235 GHz when an IF at 1.5 GHz is used. The conversion loss is 9.5-10 dB. A fixed-tuned useable IF bandwidth of more than 10 GHz was achieved with the new block design.<<ETX>>

Study of the effect of the C/sub max//C/sub min/ ratio on the performance of back-to-back Barrier-N-N (bbBNN) varactor frequency multipliers

The effect of the C/sub max//C/sub min/ ratio on the performance of planar back-to-back Barrier-N-N/sup +/ (bbBNN) frequency multipliers is studied. A simplified physical model of the device is used to relate the electrical characteristics to the material and the structural parameters. Multiplication efficiency is evaluated using a large signal analysis approach. Results indicate that if the optimum device size for a given frequency is used, a high C/sub max//C/sub min/ ratio results in high efficiency.<<ETX>>

Frequency tripler with integrated back-to-back barrier-n-n/sup +/ (bbBNN) varactor diodes in a novel split-waveguide block at 220 GHz

A frequency tripler has been developed using an integrated planar back-to-back barrier-n-n/sup +/ (bbBNN) varactor device in a waveguide mount at 220 GHz. The multiplier is based on a novel split-waveguide block design and a new fully integrated planar device architecture. Planar GaAs bbBNN devices have been combined with quartz microstrip filters in a wafer level circuit integration process. A flange-to-flange tripling efficiency of 5%, the highest yet reported from a bbBNN structure at this frequency, has been obtained. Details of the device fabrication process, block design and measured performance are presented.<<ETX>>

Integrated back to back barrier-N-N/sup +/ varactor diode tripler using a split-waveguide block

The back-to-back barrier-N-N/sup +/ (bbBNN) varactor is a nonlinear device being developed for frequency multiplier applications above 100 GHz. Its symmetrical C-V characteristic, low series resistance, freedom from external bias and suitability to planarization make it an ideal choice for high frequency, low power, odd harmonic generation. In this paper, the performance of a 220-GHz waveguide tripler using, for the first time, a planar GaAs bbBNN device integrated on a quartz microstrip circuit is presented. A new split-waveguide block design has been employed to provide the proper embedding impedances to the device at the input and third harmonic output frequencies. A flange-to flange tripling efficiency of 7% has been obtained at 220 GHz with an output power in excess of 700 /spl mu/W. This is believed to be the highest conversion efficiency yet reported for a tripler with an integrated device at this frequency. Theoretical calculations indicate that substantial improvement is possible with modest changes to the device and circuit parameters. >