Two stage RF amplifier

Claim 1

A radio frequency amplifier comprising, in combination: a first stage comprising a common source JFET having source, gate and drain in cascade combination with a first common base bipolar transistor having emitter, base and collector, the JFET gate comprising an RF input to the amplifier; a second stage comprising a second common base bipolar transistor having emitter, base and collector, the collector comprising an RF output for the amplifier; a tuned circuit coupling the first and second stages at a predetermined RF frequency; whereby an RF signal path is provided between the amplifier input and output with gain in each stage; means effective to establish an AGC voltage on the base of the second bipolar transistor, whereby the gain of the second stage is controlled in accordance with the AGC voltage; means connecting the emitter of the second bipolar transistor in series with the base of the first bipolar transistor, whereby the second bipolar transistor is effective to provide amplified direct drive current for the first bipolar transistor and thus control the gain of the first stage in accordance with the AGC voltage, the second bipolar transistor thus providing amplification simultaneously for RF and AGC signals.