![]() The detector is followed by a buffer and adjustable gain stage. To minimize the effects of the nonlinearities, a preamplifier boosts the amplitude of the input signal by 16X, thereby reducing the the diode detector’s nonlinearity effects by the same factor. The main problem with diode detectors have inherent nonlinearities, particularly for small signals. The blocks are (left-to right) top: 2 MHz preamp, unity gain buffer, and output amplifier with gain and offset adjustment bottom: +12 and +5 V regulators, 8 kHz oscillator, buffer with voltage multiplier to supply -3.5V to the op-amp.ĭiode detectors are good at changing AC into DC, even at high frequencies. Months later, I settled on the circuit shown here. I wanted a way to measure the current in some HF power circuits and thought it would be a 5 minute task to throw together a sufficiently linear peak detector and calibrate it. Encased in a pencil box to keep the point-to-point wiring on the back of the board from shorting to wires and things on the workbench, the plastic case also holds the offset and gain post as well as the input connector and the switches that switch on the near-zero and near-full scale references.
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