Patent ID: 7215274

Claim:
An analog-to-digital converter (ADC) for converting an analog input signal into a digital output signal, the ADC comprising: a coarse converter adapted to convert the analog input signal into one or more coarse bits for the digital output signal during an initial phase of a conversion cycle for the ADC; at least one fine converter adapted to convert the analog input signal into one or more fine bits for the digital output signal during a subsequent phase of the conversion cycle; a sample-and-hold module adapted to generate a stable version of the analog input signal for application to a signal input node of the fine converter; a reference-voltage supply adapted to generate and apply one or more fine reference voltages to one or more reference input nodes of the fine converter for use by the fine converter during the subsequent phase of the conversion cycle; switch circuitry connected between the sample-and-hold module and at least one reference input node of the fine converter and adapted to selectively apply the stable version of the analog input signal from the sample-and-hold module to the at least one reference input node of the fine converter; and an encoder module adapted to combine the coarse and fine bits to generate the digital output signal, wherein: during the initial phase of the conversion cycle, the switch circuitry applies the stable version of the analog input signal from the sample-and-hold module to the at least one reference input node of the fine converter to pre-charge the at least one reference input node.