Voltage regulation of virtual earth nodes of a differential signal processing circuit

A signal processing circuit comprising:

• a first processing path having a first virtual earth node;
• a second processing path having a second virtual earth node;
• a differential feedback loop configured to apply a feedback signal to each of the first and second virtual earth nodes so as to minimise any voltage difference between the first and second virtual earth nodes;
• and
• a regulator operable to monitor a voltage at the first virtual earth node against a reference voltage and to apply a regulation signal to the first virtual earth node to maintain the voltage to be equal to the reference voltage;
• wherein the regulation signal is also applied to the second virtual earth node.

A signal processing circuit comprising:

• a first processing path having a first input;
• a second processing path having a second input;
• the signal processing circuit being configured to generate an output signal based on a difference between an output of the first processing path and an output of the first processing path;
• a digital-to-analogue converter configured to apply feedback to first and second nodes of the first and second processing paths respectively based on the output signal;
• a voltage regulator configured to apply a regulation signal to each of the first and second nodes based on monitoring the voltage at just one of the first and second nodes.