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Design >> Analog Design >> Driven Right Leg circuit
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Message started by Victor chan on Dec 28^th, 2010, 4:51am

Title: Driven Right Leg circuit
Post by Victor chan on Dec 28^th, 2010, 4:51am

Here is a picture of a part of a circuit, which contains a right leg driver.

My understanding of DRL is a circuit which send a signal to a human body, therefore this human body would have the same 'common voltage' as the circuit, which helps to increase CMRR.

However, I would like to know how the below DRL works, especially at the point A, B and C.

Also I have seen quite a few of DRL circuits, and they all do some sort of filtering (Low pass filter), I would like to know what value of cut off freq is aiming actually.

Title: Re: Driven Right Leg circuit
Post by philcorb on Feb 18^th, 2011, 6:49am

Hi,

The DRL circuit essentially places the human body within the a common-mode feedback loop, mainly to minimise 50/60Hz main-hum picked up by the body. The low-pass filtering is for loop stability.

Hope this helps