Patent ID: 7961132

Claim:
An analog-to-digital converter configured for sampling an analog input signal and performing an analog-to-digital conversion process to generate a digital code representing a sampled analog input signal value, the analog-to-digital converter comprising: a capacitor having a first capacitor terminal and a second capacitor terminal, the analog input signal being selectively coupled to the first capacitor terminal and a first voltage being selectively coupled to the second capacitor terminal during a tracking period to acquire the analog input signal to be sampled on the capacitor; a sampling switch controlled to lock in the sampled analog input signal value, the sampling switch comprising a pn junction diode having a first junction terminal and a second junction terminal, the first junction terminal being coupled to the second capacitor terminal; and a controller circuit controlling the sampling switch, the controller circuit comprising a charge pump coupled to the second junction terminal, the charge pump configured for providing a second voltage to the second junction terminal during at least a portion of the analog-to-digital conversion process when the analog-to-digital converter is evaluating the sampled analog input signal value, to prevent the pn junction diode from becoming substantially conductive so as not to substantially affect an accuracy of the digital code representing the sampled analog input signal value.