Reference circuit suitable for use with an analog to digital converter and an analog to digital converter including such a reference circuit

A method of providing a reference voltage to an analog to digital converter having a charge redistribution capacitor array, the method comprising:

• receiving at an input a reference signal voltage from a reference circuit;
• providing a reference output voltage to at least one capacitor of the capacitor array;
• comparing the reference output voltage with the reference signal voltage, and based on the comparison, supplying a correction signal to reduce the difference between the reference output voltage and the reference signal voltage, the correction being supplied during a correction phase;
• and connecting a storage capacitor to the input during an acquisition phase so as to store the reference signal voltage thereon.

An integrated circuit comprising a reference circuit in combination with a charge redistribution DAC having a plurality of capacitors within a switched capacitor array, the reference circuit comprising:

• an input for receiving an input voltage from a voltage source, an output for supplying a reference circuit output voltage to the DAC;
• a storage capacitor for storing a reference voltage;
• and a voltage modification circuit for causing an output voltage from the reference circuit stored on the storage capacitor to substantially equal the input voltage, said voltage modification circuit operating during a correction phase;
• and a switch for connecting the storage capacitor to the input during the acquisition phase.