Linear Integrated Circuits (Field Effect RF Amplifier/Mixer Integrated Circuits)

An integrated MOS RF amplifier-mixer circuit, capable of receiving FM signals in the 30- to 76-megahertz frequency range, was developed successfully. The front end IC essentially met or surpassed contract specifications on sensitivity, power gain, desensitization, and spurious response. The performance of the integrated-circuit compared favorably to results obtained from circuits using discrete devices. The circuit, which consists of seven p-channel MOS enhancement devices fabricated on a common substrate, uses MOS dual-gate devices in both the direct-coupled RF amplifier and mixer stages. The MOS transistors necessary to bias these stages are included on the 30-by 40-mil pellet. The RF amplifier-mixer IC was evaluated in a typical military FM receiver at 30 and 76 megahertz. The circuit exhibited an excellent sensitivity of 0.35 and 0.4 of a hard microvolt at 30 and 76 megahertz, respectively, for a 10-dB signal plus noise-to-noise ratio at the audio output. Power gain and dissipation was 34.0 dB and approximately 100 milliwatts, respectively, for a 9-volt supply at both 30 and 76 megahertz. Desensitization results were very good with interfering signal levels, removed by 10 percent from the desired channel frequency, of at least 122 dB above the reference level required to degrade the 10-dB signal plus noise-to-noise ratio to 6 dB. The integrated RF amplifier-mixer was operated in a varactor-tuned assembly, and performed well over the 63- to 76-megahertz band.