Need EE help

[CraKaJaX]

Question: An op amp is being used with an open loop gain of 50,000 an input impedance of 3M ohm and an output impedance of 80ohms. Assume that it is being used in a non-inverting amplifier with a feedback resistor of 68K and an input resistor of 10K.

1) Calculate the closed look input imedance.

Would this be Ri + Rf/50,000? I'm pretty sure it is, I'm just making sure. I'm coming out with 10.001k ish.

2) I'm having a problem with: Calculate the closed loop output impedance.

I thought that Zout = Zout / (1+Open loop gain x B) ? And I thought B was = R1 / R1+ R2? Am I doing this part right? Cause I'm coming out with a weird number.

3) Calculate the ideal closed loop gain (assuming an ideal op amp were used)

Didn't try that one yet, but you're more then welcome to


If you could help.. I'd appreciate it. Thanks

 

[Suspicious-Teach8788]

imput impedance... ehhh just do a thevenin equivalent.

I would do this problem if I had my clipboard with me, but I have no desk space at the time to write anything down...

 

[CraKaJaX]

Thanks. I just want to know if I'm doing this right in the first place... as the way I have it up there.