In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written

more »

... permission. ABSTRACT The conversion gain of GaAs MESFET mixers is known to be dependent on the impedances seen by the applied signals and the resulting mixing products at all ports of the device. For an accurate representation, all these loading conditions should be considered; however, the design of gate and drain networks then becomes rather difficult. As a result, no sufficiently accurate and yet usable design procedures exist for MESFET mixers; instead, a few simple rules involving short-and open-circuit terminations have been given by various authors. Unfortunately, these rules are often inappropriate, particularly in upconverter applications. 14: Simplified FET equivalent circuit 40 15: LO voltages for T = 1 at 10 GHz 41 16: Large-signal S parameter measurement diagrams 42 17: CG -vs-LO reflection coefficient for sample 3 47 18: CG -vs-LO reflection coefficient including uncertainty 50 19: Typical DC characteristics of NE70083 54 20: Matching network 1 59 -vii -21: CG -vs-frequency with network 1 60 22: Matching network 2 61 23: CG and RL -vs-frequency with network 2 61 24: Dual-gate FET equivalent circuit 66 25: CG -vs-LO reflection coefficient at 1.5 GHz with T = .83 67 26: Dual-gate FET LO reflection circuit 68 27: LO voltages-vs-reflection coefficient at 1.5 GHz with T = 1 69 A.l: Nonlinear FET equivalent circuit 75 A.2: FET equivalent circuit with element harmonics 77 A.3: Conversion equations and diagram 78 A.4: Conversion equations circuit representation 79 A.5: LSB/USB interaction 79 A.6: Second LO harmonic effects 80 A. 7: Approximations of this method 80 B. 1: Modified RF/IF circuit for arbitrary loadings 83 E: Conversion Gain Simulations for Sample 3 91 F: Frequency Response of LO Voltages for T = 1 100 -viii - ACKNOWLEDGEMENTS I would first like to thank my supervisor Dr. Lawrence Young. His financial help at the early stage of my studies coupled with many informative discussions and the interest he showed throughout contributed significandy to the success of this project. I am also very appreciative of my co-supervisor Dr. Josef Fikart's direction and support during this work. His patience, poise, and insight into problems were particularly stimulating.