This report describes the design of different amplifiers that are part of an FM transceiver. This is part of a larger project, which has the objective to design a complete FM transceiver from discrete components only, meaning that IC technology is not considered.
The circuits designed are two baseband amplifiers, an intermediate frequency amplifier, a low noise amplifier and an RF power amplifier. The baseband amplifiers are implemented with a Darlington pair in common-collector configuration to achieve a high input resistance, low output resistance, and unity gain transfer.
The intermediate frequency amplifier is centered at 9.95 MHz with a -3dB bandwidth of 2 MHz. The maximum gain is 40.5 dB and can be lowered with up to 39.7 dB using a potentiometer, based on the emitter degeneration principle.
The low noise amplifier has a maximum noise figure of 1.4 dB over the RF carrier band of 88 to 108 MHz. It has a gain of 33 dB, and reaches its 1 dB compression point for an input of -33 dBm. The total harmonic distortion is less than 0.3%.
A class E power amplifier is designed with an efficiency of 72.9%, a transmit power of 3.1 W, and a gain of 31.8 dB.
Furthermore, this reports also presents a systematic design approach for amplifiers, which illustrate the core principles on which all the designs are based.