SCROD CAL buffer test results The buffer was fed with sinewave in range 150 – 750 MHz, and first the input and then the output were measured on scope for amplitude and phase w.r.t. the signal generator. A splitter of high isolation was used to tap the signal into ch3 of the scope, with FET probe soldered to SCROD (“ABUF” pin 4 and “ABUF23” pin 1). G. Visser, IU, 10/16/2014 ~400mVpp to SCROD probe ~0.8pF || 1MΩ, BW 1.5GHz Buffer output is NOT LOADED!

Typical CAL buffer output signal measurement. Total delay 490MHz. Ch3 is the version of input signal.

The magnitude of input droop, and the magnitude of output/input, are unexpected. I have to not trust the input measurement. Original hope was to cancel out the losses which must be present on input connections. Possibly there are just very significant reflections from input? Will check. Nevertheless, clearly we have −3 dB point around 450 MHz delay is a modest function of frequency, so I worry less about that than I used to… I think this circuit will perform ok Should check full path through connectors to carrier boards / terminations…

Time domain test: ~500mV p-p input “step”.

Time domain test: output, risetime ~950 ps