Diode ring mixer with driving circuitry and IF amplifier

I made this to figure out how to drive a double-balanced diode ring mixer. Both inputs are driven by a 50 ohm source. Output of the mixer is terminated with 50 ohms and the voltage is tapped and run through an IF amplifier set at 455 kHz. When building this in reality the diodes should be Schottky diodes so the local oscillator drive does not need to be as much. The transistor drivers for the inputs should also probably be implemented using a push-pull configuration (class AB) to avoid the high bias current resulting from the 50 ohm emitter resistor. Running the circuit shows the output of the IF amp which stabilizes to a sine wave at 455 kHz, i.e. the difference frequency of the two inputs.

published 10 years ago