I´m trying to find how how to find the Gain and Rin of this high pass active filter
.
http://ok1ike.c-a-v.com/soubory/tipy/HIGH PASS ACTIVE FILTER.JPG
How do I do that?
I first tried to find V_ and V+ but I don´t know how to do that.

 

The gain is 1 like a piece of wire at high frequencies because the opamp is a follower.
Its Rin doesn't matter because it must be fed from a very low impedance like the output of an opamp.

 

Thanks alot.
But do you know how to find V- and V+ ?

And what is the formula for the Gain? I need to show formulas.

 

But do you know how to find V- and V+ ?

if it is the dual polarity power supply then select the voltages to match your opamp and to match your desired max output level.

And what is the formula for the Gain? I need to show formulas.

Don't you know the calculation of gain in a non-inverting opamp circuit?
It is 1 + (Rf/Rg). This simple circuit has the opamp as a follower without Rf and without Rg so its gain is 1 at high frequencies.

 

Isn´t R1 = Rg ?

Am I supposed to take the C1 and C2 out and just short circuit it instead?

Is there no current flow in R2?

 

Thanks alot.
But do you know how to find V- and V+ ?

And what is the formula for the Gain? I need to show formulas.

Are you supposed to be able to derive the formula, or just find it?

 

Isn´t R1 = Rg ?

Am I supposed to take the C1 and C2 out and just short circuit it instead?

Is there no current flow in R2?

The output of the opamp is directly connected to the (-) input so the opamp has a gain of 1 like a piece of wire but its input impedance is very high and its output impedance is very low.
R1 applies a little positive feedback at the cutoff frequency of the filter so that the response is sharp and is not droopy.
C2 and R2 make the second RC of the second-order Butterworth filter.

 

Sorry i don´t understand those complicated explanations. I need only to know simply how to find the gain...

 

Sorry i don´t understand those complicated explanations. I need only to know simply how to find the gain...

http://www.daycounter.com/Filters/SallenKeyHP/Sallen-Key-HP-Filter-Design-Equations.phtml

 

Sorry i don´t understand those complicated explanations. I need only to know simply how to find the gain...

The "geek talk" is not complicated. It is the basics.
I explained why the gain is only 1.