High Bandwidth Digital Pot

[[email protected]]

Hi. ANyone knows about a digitally controlable potentiometer that has
a wide bandwidth. It's for a portable-scope project so I would need a
bandwidth something like 20MHz minimum. Do anyone knows if its a good
idea to use the digital pot in the feedback loop of a inverting-amp
(op-amp).
Will my signal still be clean.
Well thanks

 

[Vladimir Vassilevsky]

Hi. ANyone knows about a digitally controlable potentiometer that has
a wide bandwidth.

Take a common 100 Ohm potentiometer and attach a step motor to it.

It's for a portable-scope project so I would need a
bandwidth something like 20MHz minimum. Do anyone knows if its a good
idea to use the digital pot in the feedback loop of a inverting-amp
(op-amp).

Bad idea. Digital pot is RC-RC-RC-RC.... Stability and response will be
problematic and varying with gain.

Will my signal still be clean.
Well thanks

The design of the scope front end amps is not trivial and requires a
great deal of experience.


Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com

 

[Glenn Gundlach]

Hi. ANyone knows about a digitally controlable potentiometer that has
a wide bandwidth. It's for a portable-scope project so I would need a
bandwidth something like 20MHz minimum. Do anyone knows if its a good
idea to use the digital pot in the feedback loop of a inverting-amp
(op-amp).
Will my signal still be clean.
Well thanks

Maybe these guys have something you could use.

http://www.analog.com/en/subCat/0,2879,759%5F787%5F0%5F%5F0%5F,00.html

I used the AD603 10 years ago and it did everything AD said it would

GG

 

[[email protected]]

Maybe these guys have something you could use.

http://www.analog.com/en/subCat/0,2879,759%5F787%5F0%5F%5F0%2...

I used the AD603 10 years ago and it did everything AD said it would

GG

These pieces seem quite interesting. But since it's a portable scope,
I only use 3.3v powered devices and many of this amps require 5 or
12v. So I'm thinking about an analog multiplexer that could handle
wide bandwidths and a set of non-ajustable amps. Still, if someone has
another idea please tell me.
Thanks
Joey Caron

 

[Paul Hovnanian P.E.]

Hi. ANyone knows about a digitally controlable potentiometer that has
a wide bandwidth. It's for a portable-scope project so I would need a
bandwidth something like 20MHz minimum. Do anyone knows if its a good
idea to use the digital pot in the feedback loop of a inverting-amp
(op-amp).
Will my signal still be clean.
Well thanks

Use a programmable gain broadband amplifier.