integrator circuit design

[zxcv2201]

I would like to configure an integrator. At this time, I think the cap and resistor that make up the integrator determine the performance of the integrator. So, what should the performance of the amp be considered when making it? What standards do you use when designing?

 

[danadakk]

https://www.analog.com/media/en/training-seminars/design-handbooks/ray-stata-op-amp-articles/Operational-Integrators.pdf

Regards, Dana.

 

[KlausST]

Hi,

it´s mainly determined by your application´s requirements.

Some integrator may be fast, some may be used for rather low frequencies, some may be accurate, some may cause low distortion, some may be designed for low power ....

So the first (with every electronics design) you should do: Write down the requirements with values and units.

Klaus

 

[danadakk]

https://www.ti.com/lit/an/sboa275a/sboa275a.pdf

Regards, Dana.

 

[BradtheRad]

Give attention to the amount of current available to drive the network. Low resistor value tends to ask for greater current. High Farad value asks for greater current. Likewise consider how much current you need to drive the next stage in your project.

For low frequencies it's convenient to use electrolytic type. But your integrator might use bipolar AC. Then consider using the trick of installing two electrolytics back-to-back. Test the voltage which develops at their join in case it doesn't match their polarities.

Maybe you follow a design (example, Sallen-Key) which includes an op amp?

 

[D.A.(Tony)Stewart]

I would like to configure an integrator. At this time, I think the cap and resistor that make up the integrator determine the performance of the integrator. So, what should the performance of the amp be considered when making it? What standards do you use when designing?

I recall when my medical brother-in-law asked me in my 1st year of EE how much it would cost to make an integrator so he could compute O2 content in a patient in ICU. I was so embarrassed and ignorant at the time. After you done 1 or 2, it's trivial.

There are no standards, but there are custom requirements. So you ask the right questions to determine the specs.

1. Input & output voltage range estimate.
2. Time interval, Δt for Integrate and dump(reset), eventually it will drift.
3. Error tolerance % of FS (full scale) over time internal above.
4. For digital integrators, the analog value can be used to count up or down when some integral trigger polarity is created.

There are some practical limits that determine implementation restrictions;

1. - leakage resistance/current max in the capacitor. When possible use metal film and never use ceramic as they have hysteresis unless NP0/C0G stable types.
2. - input current of the Op Amp. Generally use CMOS / FET input types and compare Iin specs. for your tolerance requirements.
3. Combine capacitor leakage current worst case and OA input current for total leakage Ic
4. Ic= C ΔVc/Δt or the voltage integral version determines your specs and choice of parts

 

[crutschow]

It all depends upon your integrator requirements.
Please state them.