A wideband high-gain transistor amplifier at L-band

Recent progress in microwave transistor manufacturing technology has stimulated the application of transistors to microwave devices. This paper will describe a wideband high gain L-band transistor amplifier which consists of six common-emitter stages on a printed circuit board. The author describes an experimental transistor capable of providing 5-db gain per stage out to almost 2 Gc. The circuit diagram of a single-stage common-emitter amplifier is given. The emitter is grounded for rf frequencies by means of a large capacitance, and the input signal is applied to the base through a series capacitance. The collector is grounded for dc through an rf choke. To prevent rf leakage to bias circuits, the dc voltages of the emitter and base are applied through low-pass networks. A series combination of a resistor and a parallel resonant circuit in the collector circuit secures low-frequency stability, and a low-pass type output network improves output impedance matching and peaks up the gain at the high-frequency edge of the band.