Patent ID: 7230555

Claim:
A sigma delta analog to digital converter of the type adapted to be connected to a capacitive current input device, comprising: a sigma delta modulator having an input and an operational amplifier having a gain-bandwidth product; and a flying capacitor comprising a charging capacitor and a flying capacitor switch for buffering the input of the sigma delta modulator from the capacitive current input device so that the gain-bandwidth product and power dissipation of the operational amplifier is reduced, wherein the charging capacitor is coupled between the switch and ground, the switch being configured to be electrically switched between a first connection wherein the flying capacitor is electrically connected to an output of the capacitive current input device so that current signal can flow between the capacitive current input device and the charging capacitor, and a second connection wherein the flying capacitor is electrically connected to an input of the sigma delta modulator so that current signal can flow between the charging capacitor and the input of the sigma delta modulator.