Just noticed that you are making the QA451 end-of-life. If you do introduce an updated version, I would like to suggest adding the ability to turn off the 12 dB attenuation so that the unit is unity gain or as close to that as is reasonably possible. While I am making requests I will also add making the corner frequency switchable to 30KHz or even 25KHz would also be very useful. I have been using the QA451 as part of a jitter testing setup which would benefit from a unity gain setting and a lower corner frequency.
Yes, noted. About halfway down on the wiki page linked below you’ll notice a small circuit that delivers 3 atten levels. Something similar to that is being used. The corner frequency won’t be switchable, because it’s a high order filter