Method for controlling a capacitive touch pad

A system, comprising:

• a plurality of first electrodes;
• a plurality of second electrodes;
• a first electrode terminal coupled to at least one of the first electrodes;
• a second electrode terminal coupled to at least one of the second electrodes;
• a sampling capacitor having a first and a second sampling capacitor terminal, the first and second sampling capacitor terminals selectively coupled to the first and second electrode terminals, respectively;
• a charge transfer circuit that includes:
• a first voltage source;
• a second voltage;
• a first transistor coupled between the first voltage source and the first sampling capacitor terminal;
• a second transistor coupled between the second voltage source and the second sampling capacitor terminal;
• and
• a comparator coupled to the first sampling capacitor terminal and configured to compare a voltage on the first sampling capacitor terminal with a reference voltage.

A device, comprising:

• a plurality of pair of electrodes, each pair of electrodes having a first electrode terminal and a second electrode terminal;
• a charge-transfer circuit, that includes:
• a first voltage source;
• a second voltage source at a lower voltage than the first voltage source, both the first and second voltage source at voltages greater than or equal to a ground voltage;
• a sampling capacitor that is coupled between the first voltage source and the second voltage source and is configured to be charged by the first and second voltage sources, the sampling capacitor being configured to transfer charge from each pair of electrodes, the sampling capacitor having a first and a second sampling capacitor terminal, the first and second sampling capacitor terminals selectively coupled to ones of the first and second electrode terminals, respectively;
• and
• a comparator coupled to the first sampling capacitor terminal and configured to compare a voltage on the first sampling capacitor terminal with a reference voltage.