Analog-to-digital conversion with sampling capacitor pre-charging

An analog-to-digital converter (ADC), comprising:

• an input configured to receive an input signal;
• a unity-gain buffer coupled to the input, the buffer configured to receive the input signal and generate a buffered input signal;
• a pre-charge controller, the pre-charge controller including a multiplexer, the pre-charge controller configured to receive the input signal and the buffered input signal, and to selectively apply the input signal and buffered input signal to a sampling capacitor using the multiplexer, where the pre-charge controller is configured to:
• apply the buffered input signal to the sampling capacitor for a first ADC sampling cycle to pre-charge the sampling capacitor;
• in response to an end-of-sampling signal after the first ADC sampling cycle, directly apply the input signal to the sampling capacitor for a second ADC sampling cycle to final-charge the sampling capacitor, where the first ADC sampling cycle and the second ADC sampling cycle are consecutive sampling cycles;
• and
• a converter configured to generate a digital output corresponding to the final-charge of the sampling capacitor.

A method of performing an analog-to-digital conversion, the method comprising:

• applying an input signal to an input;
• buffering the input signal to generate a buffered input signal;
• applying the buffered input signal to a sampling capacitor for a first ADC sampling cycle to pre-charge the sampling capacitor;
• applying the input signal to the sampling capacitor for a second ADC sampling cycle to final-charge the sampling capacitor;
• and
• generating a digital output corresponding to the final-charge of the sampling capacitor.