[time-nuts] Sub Pico Second Phase logger

[Bruce Griffiths]

Joe

I suspect that the phase detector characteristics stated in the NIST
papers only apply when the mixer RF port is saturated.
This is evident from the Kurtz application note:

http://www.wj.com/archive/documents/Tech_Notes_Archived/Mixers_phase_detectors.pdf

 which indicates (Figure 14 and Figure 15 plus surrounding text)  that
for a high impedance (resistive) IF port termination the phase detection
characteristic only approaches a triangular wave when the RF port is
saturated (Figure 15) whereas for an unsaturated RF port (Figure 14) the
phase detection characteristics still appears sinusoidal.
The Kurtz application note also indicates that the IF port signal
amplitude reaches a maximum when the IF port termination resistance
increases (for the particular mixer) above 400 ohms.

There are no corresponding figures for the case of an IF port terminated
in a capacitor.
It would be interesting to check this.

Saturating the RF port also degrades the isolation etc, thus another
interesting question is does capacitively terminating the IF port
degrade these parameters when the RF port is unsaturated?
This may well not be the case with 5MHz or 10MHz mixer input  frequencies.


Bruce