Contains reports on three research projects.National Aeronautics and Space Administration (Grant NGL 22-009-163)Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DA 28-043-AMC-02536(E

Chen, A. Y. C.

Peterson, D. F.

Saleh, A. A. M.

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III. SOLID-STATE MICROWAVE ELECTRONICS'Academic and Research StaffProf. P. Penfield, Jr.Dr. D. H. SteinbrecherGraduate StudentsA. Y. Chen H. Po A. A. M. SalehD. F. Peterson J. E. Rudzki J. R. SelinA. MICROWAVE FREQUENCY DOUBLERThe research during this period has been concentrated on the development of theo-retical guidelines for frequency doubler design. Based on an imbedding network modelsuggested by D. H. Steinbrecher, the condition of optimum frequency doubler is derived.Through the use of a Smith chart, criteria of an optimum network, performance, andsupplementary observables can be predicted. The results are analytical. Althoughcertain limitations have been assumed at the beginning, they are reasonable in practice.From this, a systematic design approach has been formed. A frequency doubler from14. 4 GHz to 28. 8 GHz is under construction and test, at the present time.A. Y. ChenB. THEORY OF RESISTIVE MIXERSThis report summarizes a thesis submitted by the author to the Department of Elec-trical Engineering, M. I. T. , in January 1970, in partial fulfillment of the requirementsfor the degree of Doctor of Philosophy.A theoretical study has been made of mixers employing purely resistive devices.The analysis has two main parts. The first part treats the mixer as a linear periodi-cally time-variant resistance inserted in a passive linear time-invariant imbedding net-work without paying attention to the method of obtaining the resistance waveform.Different imbedding networks that allow a closed-form solution of the mixer equationsare identified and classified. A system of nomenclature introducing names such as Z-,Y-, H- and G-mixers is introduced. These designations are derived from the types ofnetwork matrices that have to be used in the analysis. The wealth of knowledge of mixercircuits analyzable in closed form is employed to find the optimum resistance waveformsfor various imbedding networks and the optimum imbedding networks for differentresistance waveforms, and, in general, to set fundamental limits on the performanceThis work was supported by the National Aeronautics and Space Administration(Grant NGL 22-009-163); and in part by the Joint Services Electronics Programs(U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DA 28-043-AMC-02536(E).QPR No. 97(III. SOLID-STATE MICROWAVE ELECTRONICS)of resistive mixers.The second part of the analysis is concerned with mixers employing diodes withexponential characteristics. The problems of the pumping waveform, pump power, andDC bias parameters are treated. The performance of different mixers is obtained andcompared for identical pump power and DC bias conditions.Other topics considered in the analysis are the sensitivity of the mixer performanceto variations in the source impedance and shape of the resistance waveform, the prob-lem of incomplete terminations of the undesired out-of-band frequencies, and the noisefigure and noise temperature ratio in mixers employing purely exponential diodes.The results of this research emphasize the importance of the method of pumpingand the proper termination of the out-of-band frequencies on the performance of themixer.A. A. M. SalehC. AVALANCHE DIODE AMPLIFIERSBy using the small-signal experimentally derived model for the avalanche diodejunction,l negative resistance reflection amplifiers are being designed and constructed.Since the diode impedance is quite frequency-dependent, however, conventional filterdesign techniques have limited value in the analysis. Also, stability becomes of primeimportance when large values of amplifier gain are desired. These two problems com-plicate the analysis considerably.A simple amplifier has been built in coaxial transmission line and uses an imped-ance transformer to bring the magnitude of the diode negative resistance close to 50 .The amplifier has a 10-dB gain with a 3. 5% fractional bandwidth at 9. 5 GHz. We hopeto achieve a gain of 15-20 dB over a 10% bandwidth, this being theoretically possiblefor the small-signal model of the avalanche diode junction.D. F. PetersonReferences1. D. H. Steinbrecher and D. F. Peterson, "Small-Signal Avalanche Diode EquivalentCircuit Model," Quarterly Progress Report No. 96, Research Laboratory of Elec-tronics, M.I.T., January 15, 1970, pp. 51-53.QPR No. 97

Solid-State Microwave Electronics

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Solid-State Microwave Electronics

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