On 05/22/2018 06:25 PM, Ignatius
Rivaldi wrote:
Hi,
A RF noob here, what is a video filter? Does it
filter video? Googling 'video filter' results in softwares
that filter videos, and 'video filter rf' results in youtube
videos explaining RF filter
In this case, we're discussing active op-amp style filters, but
using specialized high-speed op-amps that are usually used for
processing video
analog baseband signals.
On Tue, May 22, 2018, 22:30 Müller, Marcus
(CEL) < address@hidden>
wrote:
Hi
Marcus,
> Use digipots to set the R values, and use a fixed
value for C, or
perhaps selectable C as well (probably only two or three
values).
friends of mine tried to do variable attenuation for
powerline
communication frontends using digipots, and: these can be
very
frequency-selective, even below 10 MHz. Maybe they were
just using the
wrong components.
> Or, a small number (4?) of selectable L-C-R low-pass
filters, and fix the sample rates to a small number.
That sounds like a nice choice, given the existence of
highspeed analog
switches (which have gotten really affordable due to USB2,
PCIe and
USB3).
I wonder if one could build an active filter with a
(video?) opamp and
make components in the feedback branches exchangeable,
assuming the
contribution of the analog switch compared to the
effective component
values at the frequencies of interest are negligible. Then
again, this
pretty much sounds like a non-integrated digipot, doesn't
it?
Best regards,
Marcus_______________________________________________
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