wonbef
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wonbef said:can you give me some papers about simulation of input/output impedance of opamp both open loop and closed loop. thanks
Whatever levels you like. Just provide a good operating point, i.e. stay within the valid common mode range.bharatsmile2007 said:hi
when measuring the output impedance of an opamp.what voltage levels do i need to connect the input pins(inverting and non-inverting teminals) to?
Thanks
The output impedance of a closed loop (CL) opAmp depends very much on its open loop (OL) gain (OLG) : Rout(CL) ≈ Rout(OL) * (CLG/OLG). Near the limits of the common mode range the OLG gets smaller, hence Rout(CL) gets larger.bharatsmile2007 said:hi erikl,
when i change the voltage levels for the inputs, i see different output impedance.
what does that mean?
iam doing any opamp,pmos diff pair and CS(output stage)....
Thanks again...
An ideal source with a series 50 ohm resistor?i have an application where i need to simulate the output of a sensor which has an output impedance of 50 ohms, 0.45-4.5v is the range of output voltage for various pressure values...how do i design a simulate a circuit to simulate this so that i can give the resulting signal to an ADC?
You didn't mention a buffer before, and I don't see a reason, why it would be needed with 50 ohm sensor impedance.mmm...that doesnt make sense...i need to give it to an opamp/buffer right before giving to the adc....
The answer completely depends on the purpose of your simulation, that is still unclear. If you connect a load with sufficient high input resistance, you can simply model the sensor as a voltage source, as suggested by checkmate. Obviously, the simulation won't give much insights. You set a voltage and the ADC will measure it.how do i simulate the characteristics of its output signal..do i use a signal generator? or if not a function gen, what is my other alternative circuit?
if u driving capacitive load, jsut put Idc for current source =0
if u driving resistive load, then put Idc equal to the current output of the circuit source.
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