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An Amateur’s View on the P2: Diode Bridge and Gain Adjust [Part 3]

After a concise investigation on the P2’s oscillator and slew rate response, we proceed with the diode bridge and offset adjust blocks. A diode bridge can be configured as a double balanced modulator/mixer by adding transformers that “multiply” the signals, forming 2 sidebands. Remember that we can represent the trigonometric functions sin(x) or cos(x) with their complex exponential counterparts. When we do this for the product of 2 trigonometric functions and simplify, we end up with the sum of 2 trigonometric functions whose frequencies have been added and subtracted to each other. Therefore, we expect the output of the diode bridge to be a resultant wave composed of f1+f2 and f1-f2, given that f1 and f2 are the frequencies of the 2 input signals to the bridge.




Figure 1. Simplified block representation showing how the oscillator, diode bridge, P2 inputs and gain/phase adjust interact.


By doing this, DC-related noise is significantly reduced (since information from the input signal i…