Tsvelykh I. Design methods of low noise transistor oscillators in centimeter and millimeter wavelength ranges

The effect of phase noise of local oscillators of frequency converters on the performance of data transmission channels with digital modulation techniques N-PSK and N-QAM is analyzed in the thesis. A method for combining metallic cavity resonance structures with planar oscillator substrate is developed. It significantly reduces the phase noise due to the use of resonators with high quality factors while preserving the planarity of the structure. Push-push design method of oscillators is improved by using the third harmonic of the fundamental oscillation as a useful output, which is achieved by replacing the output circuit of the oscillator and allows reaching low phase noise levels in the centimeter and millimeter bands. The models of resonant structures based on microstrip transmission line, suspended microstrip line, substrate integrated waveguide and cavity rectangular waveguide resonators are developed. They are characterized by high values of quality factor (68—2978). On their basis, and using the proposed improvement of push-push oscillator design method the high-tech designs of planar and quasiplanar osillators were made. The oscillators are characterized by reduced levels of phase noise in the centimeter and millimeter wavelengths, RMS phase of the output signal reaches 0,84 deg in the millimeter range (phase noise of –96,4 dBc/Hz at offset 10 kHz from the carrier frequency of 36 GHz). A method for calculating the level of oscillator phase noise, which consists in combining Finite-Difference Time-Domain method and the method of Harmonic Balance, is proposed. The method is characterized by high accuracy, which is confirmed by discrepancies with the experimental data within +/– 5 dB. Frequency synthesizers have been developed basing on a push-push VCOs with the ouput at the second (24 GHz) and the third (36 GHz) harmonics, and the VCO integrated circuits (9,9—11,28 GHz), which are thermally stabilized suitable for mass production devices, have low levels of the integrated phase error (RMS 0,85—1,3 deg) and can be used as a local oscillators of frequency converters in the antenna outdoor unit of digital communications channels with modulation methods up to 8-PSK and 32-QAM.