Hi Norbert, Thank you for your post and welcome to our forum! You can drive the shield with the same common-mode voltage as seen on the input ECG/EEG channels. The goal is to reduce capacitive coupling between the signal wires and the shield, so making them as close as possible is key. The RLD/BIAS electrode typically drives an inverted common-mode signal back to the body to help suppress common-mode noise. There's some debate as to whether the shield should be driven with the inverted commmon-mode signal or if the RLD/BIAS output should be inverted once again before driving the shielding. It may not make a whole lot of difference, but I'm not completely sure. At a minimum, I would drive the shield to a DC voltage close close the common-mode of your input signals. This is normally close to mid-supply, which is set by the BIAS amplifier driving the body. Best regards,
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