# AMP01 instrumentation amplifier

Hi

Can anyone tel what is function of RC in the above figure.

• Hi Vijay,

AMP01 gain is 20 Rs/Rg, so at low frequencies the capacitor  will look like an open circuit thus giving you a gain of 20. While at high frequencies it will be short circuit and that gives you a gain of ~500. The RC circuit will provide some rejection of dc offsets and low frequency noise for an ac measurement.

By the way, may I know your application? Thanks.

Regards.

• Thank you Jinol.

For the above circuit although ratio of Rs and Rg is same for different combination of Rs and Rg the passband cut-off frequency varies.For ex Rs=100k and Rg=100k and other combination Rs=10k and Rg=10k although ratio is same passband cut-off frequency is different.Can any one tell a relation bet resistor values and cutoff frequency.

Thank you

Regards

• Hi Vijay,

Sorry for the delayed response. Let's say for example we have a simple passive RC bandpass filter, the cutoff frequency is dependent on the values of the capacitor and the resistor. The cutoff frequency of the filter follows the formula:

fcutoff = 1/(2*pi*R*C)

You can try this tutorial (analog filters) for more information on filter design. Also, you can visit FILTER WIZARD | Analog Devices to help you on your future filter designs.

Regards,

Jino