The experiment was designed and built in-house at MIT. It was operated with a 3 microsecond pulsed power supply. An initial beam test was implemented which confirmed operation of the TWT at 31 kV with 306±6 mA of current detected at the collector and 88 % transmission of current. Operation of the TWT with the first structure showed 8 dB of system gain and 10 W saturated output power at 95.5 GHz. Following these first tests, the magnetic field alignment was improved and the second structure, which showed better circuit transmission in cold test, was installed. The overmoded TWT produced 21±2 dB system gain (defined as Pout/Pin) at 94.3 GHz and 27 W of saturated output power in zero-drive stable operation. The TWT was estimated to have about 6 dB of additional loss due to coupling into and out of the circuit. Taking that loss into account, the gain on the TWT circuit itself was estimated to be 27±2 dB circuit gain. CST simulations for the experimental current and voltage predict 28 dB circuit gain, in good agreement with measurements.
Discrete solid-state high-power amplifiers are among the important circuit components in today’s wireless communications and remote-sensing applications. As the device technologies continue to improve, there are new opportunities and new challenges presented to power amplifier designers. This thesis presents novel techniques in the design and the analysis of L-band high-efficiency power amplifiers, which may be used in many communications and radar applications.
In this work, high-efficiency power amplifier topologies are discussed and implemented. The goal is to push the boundary of output power, operating frequency, efficiency and bandwidth. Also, the design of a key passive component, a balanced-to-unbalanced transformer (balun) is discussed in detail. Some new designs of the baluns are shown, and the results show advantages of these baluns over some of the traditional work at L-band.
The stability analysis of power amplifiers is one of the most critical and the most challenging aspects of power amplifier design. This work shows an analysis technique, which accurately predicts the oscillations in power amplifiers. Using the technique, different stabilization techniques and circuits are designed and implemented.
PA Design Thesis_very Good | Amplifier | Capacitor