CW and pulsed TWTA phase noise reduction techniques.

摘要

TWTs are the primary choice in high power RF amplifiers and are employed in single units, in cascade with other amplifiers or in arrays in radar systems. In spite of its high efficiency and high power handling capability at high frequency, the inherently poor noise behavior of the TWT is an obstacle in many applications. An extremely accurate phase characteristics and substantial phase noise reduction of TWTA in radar transmitters are consistent demands to be able to distinguish wanted target signal from strongly reflected clutter backgrounds. The phase noise is mainly driven by voltage fluctuation of high voltage power supply whose conventional regulator consists of high volume of capacitive unit. The thesis presents a prominent method of reducing the phase noise in design of a compact, light, and inexpensive additional circuitry. The technique based on phase-locked loop works both at CW and pulsed mode of operation, therefore its rage of application is ubiquitous. The remarkable phase noise reduction, 24dB reduction for CW mode and over 20dB reduction for pulsed mode, can minimize the size of regulator in power supply unit achieving higher efficiency or increasing detection capability of radars.