Hi,

I am wanting to match the output of a SA602 Mixer to a 45MHz, 4-pole
crystal filter and then match the output of the filter to the input
of a SA605 IF receiver.

The filter datasheet specifies the termination impedance of 800 Ohms and
3pF.

I have not used crystal filters before and would appreciate some advice
for typology of a suitable match.

The SA605 has a input impedance of 4500 Ohms par 3.5pF. Apparently they
have a "sweet spot" if matched to 800R.
The SA602 has output impedance of 1500 Ohm (not sure of capacitance).

From what I can see, if I placed a 1k resistor across the SA605 input,
this would give me close to 800R//3pF but not max. transfer of signal.

Some of the confusion I have is what to do with the 3pF termination
requirement. I am not sure if this means that I could match the
resistive components using an "L" or "Tapped C match" and then add
another 3pF to each side of the filter ???


Any help much appreciated

Regards

David