Crystal Filter impedance matching ?

[emax0198]

crystal filter matching

For a 10.7 MHz crystal filter the input and output impedance specified by the manufacturer is 3.0kohm but the circuit requires 330ohm input/output impedence.

Now how or what kind of resistive network is required to match. Should the resistance be connected in series or parallel? I don't know the equivalent circuit of this filter.

 

[vfone]

crystal filter impedance matching

I would not recommend a resistive network for filter matching. It will increase the insertion loss.
Try an LC network.
A small software as WinSmith or RFsim99 will help you.
You can download RFsim99 from here (go to Tools/Design/Match):

 

[pool_77]

10.7 crystal if filter

-try to search for circuit examples at manuf. site of filter.

- e.g. AADE filter design prog. can help you to match
- simple wideband matching by C and R are commonly better for low ripple and higher stopband

 

[Circuit_seller]

crystal filter impedance

Hi

You can also use a transformer to do impeadance matching. for your case ohm ratio is 3000/330 = 9.

Regards