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.