A 1.1 to 2.4 GHz transistor amplifier with low noise figure and good power match

A potentially low cost amplifier module has been made using transistor chips with thin film, beam lead or chip components in a hybrid microwave integrated circuit. The design of this amplifier demonstrates a technique which has been devised to obtain input power match with minimum noise figure. This uses feedback to achieve the power match whilst maintaining, at the transistor input terminals, the source impedance required for minimum noise figure. The amplifier uses transistor chips from low-noise `slices¿ of the Mullard BFR90, which, without feedback, would give a mismatch (v.s.w.r.) of > 3: Over a bandwidth of 300 MHz, centred on 1.5 GHz, the coincident conditions have been achieved, resulting in an amplifier noise figure of 3.5 dB and input v.s.w.r. < 1.25:1 for 50 ohm source. The gain of the two-stage matched amplifier is between 16 and 12 dB from 1.1 to 2.4 GHz.