Greetings!
We need your help - Are you good with LTSPICE or another SPICE-based variant?
We're developing a passive, low-pass roofing filter network for universal use in direct conversion receivers.
In the block diagram shown below -- it goes between point A and B -- to gradually roll of high frequencies before any other low-pass or bandpass audio filters.
This network has 4 only components and is driven with a low impedance like most low-pass filters. The low output impedance is simply the output port of an op-amp voltage follower. that follows a common base audio preamp.
The job is to sweep the filter while varying some of the component values to help develop
the optimum network components. We'll test these filters designs with actual listening tests -- feedback and tweak until we settle on our ideal network components.
This filter will go on our direct conversion receiver project web page.
We simply don't have time to perform every needed task and seek assistance from someone who has time to take on this job.
Please email us if you have the time and ability to help.
Thank you!
Lid and MJ
