Bench's Test-Set
Description:
This functional-block diagram show a test-set in which you can note the presence of three buffer for a correct coupling of an oscillators (DUT-OSC) with RF instrumentation (50 Ohm typical) and a suitable system to scope-visualization of module and phase of an ILO's output signal against the input.
The input buffer is a used for input-signal's generator coupling, is implemented with a BJT (BFR91) in a simple CE (common-emitter) configuration. Obviously DUT-OSC is external ILO.
The output buffer is a similar to input one but is for coupling of ILO with: oscilloscope, frequency counter, peak-detection (diode-type) circuitry, mixer and spectrum analyzer (with another dedicated buffer).
The mixer, 50 Ohm loaded, is wired to a LC-lowpass-filter and therefore amplificated by an operational amplifier.
With this set-up we can see or input and output signal into the scope (switch1a/b in pos.1) or module and difference of phase of ILO oscillation (switch1a/b in pos.2). This way permit simply to see phase's transients in lock/entrainment/unlock conditions for analyzed ILO.
Realization:
