Techniques, devices, and systems for isolating, by isolation circuitry connected to a power source, a voltage from the power source, receiving, by sensing circuitry, the isolated voltage, receiving, by the sensing circuitry, a reference voltage from an implantable reference electrode via a reference node, and sensing, by the sensing circuitry, the biomedical signal with two or more implantable sensing electrodes using the isolated voltage with respect to the reference voltage.