A 1 KW Pulsed amplifier using MESFET, LDMOS and Bipolar transistors at 2856 MHz

Abstract

The 1 Kilo-Watt Amplifier Pulsed amplifier has been designed and tested for driving a Klystron power amplifier. The amplifier consists of a Class A multistage, single ended pre-driver using commercially available MESFET devices and consists of bias sequencing and voltage regulation. The 30 dB gain Amplifier operates from a single supply. The pre-driver is followed by a 50 Watt GaN single stage amplifier that is biased at a very low current Class AB mode. The power amplifier output stage has been designed using both Bipolar and LDMOS transistors. A four way Gysel power splitter / combiner is used to combine four Class C Bipolar pre-matched transistors capable of producing a pulsed power output in excess of 250W each with a duty cycle of 1%. A second power amplifier stage utilizes eight LDMOS transistors which are combined using commercial-off the shelf hybrids has also been made with the same foot print. The complete amplifier, either with the Bipolar or LDMOS transistors, has delivered in excess of 1 KW of pulsed power at 2856 MHz with a pulse rise time of better than 100nsec. This paper presents the design and measurements of the amplifier.