I am trying to scale an existing front end receiver (butterworth bandpass) filter to a different frequency range. Unfortunately, it has a transformer in the original design, so I'm stuck. I also don't know how to handle the load presented by the active front end component other than it's probably not significantly reactive.
The existing filter is for a 7 Mhz receiver, I'd like to have a similar filter design for 50 to 200 Khz.
The filter components and transformer winding details are in the document at:
The input chip is an FST3126, spec sheet is at:
The spec for the T30-2 transformer core is at:
I have aade filter design software, but it isn't allowing me to plug in the transformer into the design page of the software....so, I need to know it's equivalent circuit I think.
The transformer winding details are on page 4 of the document and the schematic of the front end is page 9. Ultimately, I need new values for L1, L2, C20, C21 and C22.
If someone can give me a reasonable guess as to the equivalent circuit of the transformer and the IC (U5), I can do the rest of the job myself using the aade filter software.
Thanks,
T