opamp

[ElectronicStudent]

There is in multimsim an ideal opamp with 3 terminals?

And by "ideal'' i mean:

- Infinite input impedance

- Infinite closed loop gain

- Output impedance equal zero

I just start to use multisim and I am having a lot of troubles to understand how I can use it to create the circuits in my book (linears and ideal circuits, with ideal componentes)  to help me in my circuits subject in college.

thanks

[rramos]

Please, 

Help to maintain the Forum organized. Don't post the same doubt twice: http://forums.ni.com/t5/Discuss%C3%A3o-sobre-Produtos-NI/Amplificador-Operacional-Ideal/m-p/2159528/...

[ElectronicStudent]

OK, sorry. It's because i wasn't very confident about getting a response in the portuguese forum 😄

thanks

[OStep]

In simulation, the closest you can come to an ideal op-amp is by using a voltage controlled voltage source with a very high open-loop gain. Use the component VOLTAGE_CONTROLLED_VOLTAGE_SOURCE. Simply ground the negative output terminal and you have the three terminals of an op-amp. 

The only behavior that will not be ideal is the open-loop gain, which must be finite. But with a gain of 1e6 or higher, you'll get pretty close to an ideal op-amp, and the simulation will not differ (within many decimal places) from any calculations based on infinite open-loop gain. 

[ElectronicStudent]

Thanks a lot!! Your answer was vey helpfull! I`will try that!!

[ElectronicStudent]

I am now trying to create a new component that is a "Voltage Controlled Voltage Source" with the negative terminal grounded just as you said and the simbol is a 3terminals OpAmp symbol...but I am having some troubles to get it...Could you help me?

[OStep]

See attached file.

The two circuits both use the voltage controlled voltage source as the model. In the lower circuit, I've simply created a new component with an op-amp symbol. You can see the actual SPICE model by clicking the Edit model button inside the component's properties.

Thanks,

[ElectronicStudent]

Thanks a lot man, I will try do that by myself sometime....thanks