Transconductance operational amplifier

[riie]

Hi all,

Does anyone know how do I connect if I want to use it as a voltage-controlled current source, meaning that it will ouput an AC current when i supplied an AC voltage?

And how do I adjust the gain or transconductance, gm?

For example, OPA860 with pinout E,C,B, Iq.
https://www.ti.com/lit/ds/symlink/opa860.pdf

 

[FvM]

Which application parameters make you think that a transconductance amplifier is a suitable solution?

Mentioned OPA860 would be interesting for very fast (> 10 MHz range) apllications.

 

[riie]

OPA860 is just an example. Perhap LM13700?

I'm wondering how do you actually connected a transconductance operational amplifier up if you want to use it as a voltage-controlled current source. My application is less than <200hz.

Is there such an application to use ota to convert voltage to current? I can't find much info online regarding transconductance operational amplifier

And are there are some other IC that can convert ac voltage to ac current?

 

[godfreyl]

Hi all,

Does anyone know how do I connect if I want to use it as a voltage-controlled current source, meaning that it will ouput an AC current when i supplied an AC voltage?

And how do I adjust the gain or transconductance, gm?

For example, OPA860 with pinout E,C,B, Iq.
https://www.ti.com/lit/ds/symlink/opa860.pdf

That's explained in the PDF you linked. Look at the "Application Information" section, especially the part under the heading "Common-E Amplifier or Forward Amplifier".

In a nutshell:

• Apply input voltage to pin 3.
• Take output current from pin 7.
• Set transconductance with a resistor from pin 2 to ground.
• Set quiescent current with a resistor from pin 1 to V-.

 

[FvM]

Compared to the V/I converter I suggested in your previous thread, an OTA is basically less accurate, less linear and also exposing a systematical temperature drift. Thus I can hardly imagine that it's a suitable alternative for your application. The main advantage of an OTA is it's programmable transconductance.