Contains research objectives and summary of research on two research projects.Joint Services Electronics Program (Contract DAAB07-76-C-1400

Allen, Barry R.

Burke, Bernard F.

Giuffrida, Thomas S.

Gupta, Madhu S.

Parrish, Alan

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X. MICROWAVE AND MILLIMETER WAVE TECHNIQUESAcademic and Research StaffProf. Bernard F. Burke Prof. Robert L. Kyhl Prof. David H. StaelinProf. Madhu S. Gupta Dr. Alan ParrishGraduate StudentsBarry R. Allen J. Antonio Garcia-Barreto Aubrey D. HaschickPatrick C. Crane Thomas S. Giuffrida Robert C. Walker1. MICROWAVE DEVICE AND NOISE STUDYJoint Services Electronics Program (Contract DAAB07-76-C-1400)Madhu S. GuptaThe objective of these studies is to develop improved signal and noise models forsolid-state microwave devices. These models are useful for accurate prediction ofdevice characteristics, optimization of design, and improvement of performance in cir-cuit applications. The three devices of interest at present are silicon BARITT diodes,GaAs microwave FETs, and high-efficiency IMPATT diodes.a. BARITT DiodesWe have fabricated BARITT diodes and made a detailed characterization of their non-linear properties at microwave frequencies. The measured parameters include small-signal and large-signal device impedance, frequency-modulation sensitivity, and linearityof modulation. We report the following achievements:(i) An improved method of measurement of large-signal impedance for nonlineardiodes. In this method the sensitivity of measurement is high even when the deviceimpedance is small (VSWR high), and the RF voltage across the device can be measuredindependently.(ii) We have devised a lumped-circuit model for BARITT diodes. This model hasshown better agreement with experimentally measured devices; improvement has beenfound over a wider frequency range than in previous models and its elements can begiven physical interpretation.(iii) An extensive set of large-signal measurements for a device with known param-eters has provided a data base for evaluating the theoretical nonlinear models of theBARITT diode. This work is reported in the Ph.D. thesis of Gary K. Montress,l anda paper is being prepared for publication.b. GaAs Microwave FETsIn the past, work on GaAs FETs has been the experimental characterization of aPR No. 119(X. MICROWAVE AND MILLIMETER WAVE TECHNIQUES)device in order to relate it to its model.2 This model was used to design an optimumlow-noise microwave amplifier with the device under low-temperature operating con-ditions. 3 An attempt has been made to construct this optimized amplifier. 4 Measure-ments on the amplifier have suggested that the biasing of the device can be modified toimprove the stability, with a small sacrifice of amplifier performance.c. High-Efficiency IMPATT DiodesOur research on high-efficiency IMPATT diodes is directed toward measuring oscil-lator noise spectra. Quantitative agreement between experimentally measured and the-oretically calculated noise spectra has not been achieved for high-efficiency IMPATTdiodes. Recent theoretical analyses5 show that the FM noise measure can be calculatedreasonably well if the effect of signal power level upon temperature, and of temperatureupon the reverse saturation current, is accounted for. We are attempting to measureboth AM and FM noise spectra, as well as the correlation coefficient. These measure-ments will be used for comparison with theoretical results.References1. G. K. Montress, "Fabrication and Large-Signal Characterization of BARITTDiodes," Ph.D. Thesis, Department of Electrical Engineering and Computer Science,M. I. T., October 1976.2. J. F. Cooper and M. S. Gupta, "Microwave Characterization of GaAs FETs and theVerification of Device Model" (to appear in IEEE J. Solid-State Circuits).3. J. F. Cooper, "Characterization of a Microwave GaAs FET at Low Temperature,"S.B. and S.M. Thesis, Department of Electrical Engineering and Computer Science,M. I. T. , June 1976.4. J. C. Carrick, "Construction and Measurement of High-Frequency Amplifier withGaAs FETs," S.B. Thesis, Department of Electrical Engineering and ComputerScience, M. I. T. , August 1976.5. H. Statz, R. A. Pucel, J. E. Simpson, and H. A. Haus, "Noise in Gallium ArsenideAvalanche Read Diodes," IEEE Trans. on Electron Devices, Vol. ED-23, No. 9,pp. 1075-1085, September 1976.2. ATMOSPHERIC REFRACTION AT MILLIMETER WAVELENGTHSJoint Services Electronics Program (Contract DAAB07-76-C-1400)Bernard F. Burke, Alan Parrish, Thomas S. Giuffrida, Barry R. AllenThe microwave aperture synthesis interferometer (described in Section XIII-6 andin previous RLE Progress Reports) will be used to study refraction and absorption inthe Earth's atmosphere. The initial measurements will be made at 13 mm. In January1977, we shall begin to make measurements at high and low angles of elevation, undera variety of weather conditions. The system will be converted to operation at 7 mmPR No. 119(X. MICROWAVE AND MILLIMETER WAVE TECHNIQUES)during 1977.Interference fringes have been detected at 13 mm by the entire digital system. The150-MHz correlator works well, and the measurement phase of the project awaits onlythe interfacing of the digital delay system with the computer, and the completion of the3-element correlator and phase reference controls.PR No. 119

Microwave and Millimeter Wave Techniques

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Microwave and Millimeter Wave Techniques

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