Autodyne Circuit


Posted on Feb 4, 2014

An Autodyne circuit combines three functions normally found in different stages in an RF Receiver into a single circuit. However the three stages which are the RF amplifier, the Mixer and the Local Oscillator are normally found concatenated together. Although each stage in a normal receiver would have an individual amplifier. In the case of an Aut


 Autodyne Circuit
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odyne design, the RF amplifier, mixer and oscillator use the same transistor amplifier The RF amplifier stage is that portion of an RF receiver that receives a signal from the antenna and amplifies the signal so that it is usable by the following circuitry. In regards to this example the RF amplifier would have been a low-noise high-gain transistor amplifier circuit. The Mixer Circuit would be attached, and follow the RF amplifier and use its own transistor [or other device] to combine the RF signal with the signal generated from the local oscillator. The mixer stage would then output its signal to the IF stage. The Local Oscillator circuit is designed to output a frequency that when mixed with the incoming RF will produce the correct Intermediate Frequency [IF] used by the rest of the circuit. Normally the Local Oscillator [LO] is designed to function as a stand-along circuit. The Autodyne circuit shown above combines all three functions into a single design, using one transistor as both the amplifier and combiner. The circuit amplifiers the RF, functions as an oscillator and mixes the two signal together. The Autodyne schematic is just an example. The PNP transistor could just as well be an NPN type, a FET or any other amplifying component. In addition, the Common-Emitter circuit used is just one of three possible configurations for a transistor. The style and type of oscillator could also take any form, this one appears...




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