Optimum Circuits for GaAs Oscillators: A Theoretical and Experimental Study of Device-Circuit Interaction and Maximum Limits of Operation.

摘要

The report is a study of the Limited Space-charge Accumulation (LSA) microwave oscillation using bulk GaAs material. The optimum circuit configuration and parameters were determined theoretically and verified experimentally. The theoretical study made extensive use of a time domain computer simulation that was found to be an accurate representation of the actual observation. In the course of the theoretical study,the device itself was analyzed and several simplifications in the concept of its operation were found to be true. This related to the use of a simple current versus voltage characteristic for a device that can have an unstable and complex internal electric field configuration. A further result of the simulation,was to set a realistic upper limit on the dc to RF conversion efficiency of this oscillation mode. Experimental circuits were constructed for the purpose of viewing voltage and current waveforms for direct comparison with the computer generated data. This comparison and other data confirmed the predictions and implications of the theoretical study. That is,the GaAs device can in all but several special circumstances be described by a relatively simple current-voltage characteristic,that requires minimal previous history informatio. The circuit must satisfy special requirements at the fundamental and first three to five harmonics. (Author)