OTA as integrator

[salil87]

Hi
What kinds of OTA integrators are available and how should i decide which to use?
Thanks
Salil

 

[Baluncore]

What are you trying to integrate?
Why do you need to use an OTA?
How will you trigger a reset?

 

[salil87]

I am integrating the Analog signal for a dual slope ADC. But since the input is a large signal won't the gm vary with the input level?
Thanks
Salil

 

[Baluncore]

The traditional solution would be a Miller Integrator.
See; http://en.wikipedia.org/wiki/Operational_amplifier_applications#Inverting_integrator

 

[analogdesign]

I'm not sure you can buy OTAs off-the-shelf... I think they are only useful as internal components in an IC. The problem with an OTA is while you can implement simpler integrators with them in theory, they can't drive resistive loads and are therefore less interesting in practice.

 

[analogdesign]

I am integrating the Analog signal for a dual slope ADC. But since the input is a large signal won't the gm vary with the input level?
Thanks
Salil

Yes. That's way people usually use op amps for this type of thing. See Baluncore's post. You want to use a Miller Integrator.

 

[Baluncore]

I'm not sure you can buy OTAs off-the-shelf ...

Look at
LM13600, LM13700, CA3080, CA3280, LM3080, CA3094, LT3469,
OPA460, OPA461, OPA660, OPA661, OPA860, OPA861, OPA2662
NE5517, MAX435, MAX436, NT996,

 

[analogdesign]

Well I certainly stand corrected!