Method and apparatus for analog-to-digital conversion using a tank capacitor

A processing unit, configured to control an apparatus for converting an analog signal to a digital signal, the apparatus comprising:

• a sampling capacitor coupled to an input node to be set to an input voltage that is based on the analog signal,
• a tank capacitor coupled to the sampling capacitor,
• wherein the sampling capacitor is configured, when operating in a sampling mode, to exchange charge with the tank capacitor, and, when operating in a hold mode, to hold a sample voltage,
• the apparatus further comprising a current source coupled to the tank capacitor, wherein the current source is configured to change an amount of charge stored on the tank capacitor,
• wherein the processing unit is configured to process a tank voltage across the tank capacitor.

A method for use in operating an analog-to-digital converter to convert an analog signal into a digital signal, wherein a tank capacitor is coupled to the analog-to-digital converter, the method comprising:

• setting an input node of the analog-to-digital converter to an input voltage that is based on the analog signal;
• switching a current source to the tank capacitor to change an amount of charge stored on the tank capacitor;
• disconnecting the current source from the tank capacitor;
• using the input voltage to derive a digital voltage;
• in a sensing mode, setting the input voltage to a sampling capacitor,
• in a non-sensing mode, providing a sample voltage of the sampling capacitor to a comparator;
• and
• using the tank capacitor to charge the sampling capacitor.