Design and development of a generic switch-mode power supply hold-up module for pulsed power amplifiers

Abstract

This study describes the design and development of a Switch-Mode Power Supply (SMPS) based power hold-up module for Radio Frequency (RF) power amplifiers. High power solid-state power amplifiers require high power at low voltages, which means that they must be supplied with high peak currents. This can be achieved by utilizing an energy storage capacitor bank placed closely to the RF power amplifier. The energy storage bank would then supply the high peak currents, while keeping the source power supply current low, and thus reducing the capacity (and size) requirements for the source power supply. The power supply is designed to maintain a tightly regulated supply voltage at the onset of each transmit pulse. During the transmit pulse, the regulator function is disabled and load power is provided in total from the energy stored in electrolytic capacitors. The module must be able to generate these outputs from the ma in power-conditioning unit, with the minimum and maximum pulse lengths, as well as, at the required Pulse Repetition Frequency (PRF). The use of a SMPS is introduced to the charging circuitry for its efficiency, size and weight benefits. The design is such that the switching intervals of the SMPS are configured to accommodate the transmitting windows to ensure that a following pulse is available when the next transmit command is set. Simulations, calculations and test results are presented and the test results are compared with the theoretical simulated design results to conclude the hypothesis. The results demonstrated that the SMPS implementation yielded great benefit to the efficiency, sensitivity and physical size of the power hold-up module.