09-17-2012 07:12 PM
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
09-18-2012 08:03 AM
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/...
09-18-2012 01:23 PM
OK, sorry. It's because i wasn't very confident about getting a response in the portuguese forum 😄
thanks
09-25-2012 10:29 AM
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.
09-26-2012 08:11 PM
Thanks a lot!! Your answer was vey helpfull! I`will try that!!
09-29-2012 02:54 PM
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?
10-01-2012 09:02 AM
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,
10-01-2012 10:55 AM
Thanks a lot man, I will try do that by myself sometime....thanks