Common Mode Interference Suppression In An Amplifier Circuit For A Neuromodulation Device

A neuromodulation device for measuring one or more biological electrical signals in response to a neural modulation of biological tissue, wherein the neuromodulation device comprises one or more amplifier circuits including:

• an input stage with two input terminals, configured to receive an input voltage signal, which is based on the biological electrical signal and comprises a common mode, CM, voltage signal and a differential mode, DM, voltage signal;
• a differential transconductor comprising a non-inverting input and an inverting input, each connected to one of the two input terminals, and comprising an output for providing an output current signal based on the DM voltage signal;
• wherein the transconductor is configured to provide a first CM voltage signal, which is tapped after the non-inverting input, and a second CM voltage signal, which is tapped after the inverting input;
• and
• a CM amplifier configured to combine the first CM voltage signal with the second CM voltage signal to obtain a combined CM voltage signal, amplify the combined CM voltage signal with an inverting gain to obtain an inverted CM voltage signal, and provide the inverted CM voltage signal to the non-inverting input and the inverting input of the transconductor.