A successive-approximation register (SAR) analog-to-digital converter (ADC) includes a SAR circuit configured to generate a digital code based on an analog input signal. A digital-to-analog converter (DAC) is configured to convert the digital code to an analog voltage. The SAR circuit is further configured to generate a digital output signal based on a comparison between the analog input signal and the analog voltage. A first capacitor is configured to provide a reference voltage to the DAC. An adaptive charging module is configured to stabilize the reference voltage provided to the DAC by selectively connecting to a supply voltage during a first operating phase of the ADC to store a charge in the adaptive charging module and selectively connecting to the first capacitor during a second operating phase of the ADC to combine the charge stored in the adaptive charging module with a charge of the first capacitor.