A method of operating an analog-to-digital converter, ADC, circuit to convert an analog input signal, the ADC circuit including a first capacitor circuit and a converter circuit, wherein the converter circuit comprises an amplifier, and wherein a first terminal of the first capacitor circuit is coupled to an ADC input and a second terminal of the first capacitor circuit is coupled to an input of the amplifier, the method comprising: opening a first switch coupled between the second terminal of the first capacitor circuit and a bias voltage to decouple the first capacitor circuit from the bias voltage while the first terminal of the first capacitor circuit is receiving an estimate value, wherein the estimate value is a value of the input signal that is estimated to occur at or close to a subsequent sampling instance, such that the estimate value is sampled across the first capacitor circuit; after opening the first switch, opening a second switch in the converter circuit at the subsequent sampling instance while the first terminal of the first capacitor circuit is receiving the analog input signal, wherein the opening of the second switch samples a representation of an amplified combination of a noise voltage and a difference signal that is generated between the sampled estimate value and the analog input signal across a second capacitor circuit, the second capacitor circuit coupled to an output of the amplifier; generating a digital output using the sampled representation of the amplified combination of the noise voltage and the difference signal; and converting the digital output to an analog signal representative of the digital output using a digital to analog converter circuit, and feeding back and coupling the analog signal representative of the digital output to the first terminal of the first capacitor circuit to adjust a voltage applied to the first terminal of the first capacitor circuit for performing a successive approximation search, wherein the ADC input is decoupled from the first terminal of the first capacitor circuit before coupling the analog signal representative of the digital output to the first terminal of the first capacitor circuit. opening a first switch coupled between the second terminal of the first capacitor circuit and a bias voltage to decouple the first capacitor circuit from the bias voltage while the first terminal of the first capacitor circuit is receiving an estimate value, wherein the estimate value is a value of the input signal that is estimated to occur at or close to a subsequent sampling instance, such that the estimate value is sampled across the first capacitor circuit; after opening the first switch, opening a second switch in the converter circuit at the subsequent sampling instance while the first terminal of the first capacitor circuit is receiving the analog input signal, wherein the opening of the second switch samples a representation of an amplified combination of a noise voltage and a difference signal that is generated between the sampled estimate value and the analog input signal across a second capacitor circuit, the second capacitor circuit coupled to an output of the amplifier; generating a digital output using the sampled representation of the amplified combination of the noise voltage and the difference signal; and converting the digital output to an analog signal representative of the digital output using a digital to analog converter circuit, and feeding back and coupling the analog signal representative of the digital output to the first terminal of the first capacitor circuit to adjust a voltage applied to the first terminal of the first capacitor circuit for performing a successive approximation search, wherein the ADC input is decoupled from the first terminal of the first capacitor circuit before coupling the analog signal representative of the digital output to the first terminal of the first capacitor circuit.