Broadcast Band Rf Amplifier Circuit


Posted on May 13, 2012

The circuit has a frequency response that ranges from 100 Hz to 3 MHz; the gain is about 30 dB. Field-effect transistor Ql is configured in the common-source self-biased mode; optional resistor R1 allows you to set the input impedance to any desired value. Commonly, it will be 50 . The signal is then direct-coupled to Q2, a common-base circuit that isolates the input and output stages and provides the amplifier`s exceptional stability. Last, Q3 functions as an emitter-follower, to provide low output impedance (about 50 ).


Broadcast Band Rf Amplifier Circuit
Click here to download the full size of the above Circuit.

If you need higher output impedance, include resistor R8. It will affect impedance according to this formula: Rs ~ ^0lJT - 50. Otherwise, connect output capacitor C4 directly to the emitter of Q3.




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