Methods and systems for analog-to-digital conversion using two side branches that may be operated with overlapped timing such that a sampling phase may be overlapped with a previous conversion phase. Some embodiments provide a method of successive approximation A/D converting, comprising sampling a first signal onto a first capacitor that is configured to selectively couple to an analog input of a comparator, sampling a second signal onto capacitors that are coupled to a second analog input of the comparator and configured for charge redistribution successive approximation A/D conversion; carrying out, based on the first signal and the second signal, a charge redistribution successive approximation A/D conversion using the capacitors; and while carrying out the charge redistribution successive approximation A/D conversion based on the first and second signals, sampling a third signal onto a third capacitor that is configured to selectively couple to the analog input of a comparator.

Embodiments of the present invention provide a digital-to-analog conversion circuit, where the digital-to-analog conversion circuit includes a signal amplitude detector and a digital-to-analog converter. When the signal amplitude detector detects a low signal amplitude, a first current module in the digital-to-analog converter operates normally and a second current module in the digital-to-analog converter stops operating. In addition, when stopping operating, the second current module is in a state of a third bias voltage and a fourth bias voltage that are generated by a second bias circuit. When the amplitude detector detects a high signal amplitude subsequently, the second current module resumes normal operation. After operating normally, the second current module switches back to a first bias voltage and a second bias voltage that are generated by a first bias circuit. This reduces a nonlinearity problem caused before a second current module resumes normal operation.

A system can include an analog input port; a digital output port; and a successive approximation register (SAR) analog-to-digital converter (ADC). The SAR ADC can include a voltage comparator V.sub.d having a first input, a second input, and an output; a first plurality of capacitors C.sub.p[0:n] that are coupled with the analog input port and each have a top plate and a bottom plate; a second plurality of capacitors C.sub.n[0:n] that are coupled with the analog input port and each have a top plate and a bottom plate; and a SAR controller coupled between the output of the voltage comparator V.sub.d and the digital output port.

An Analog to Digital (ADC) is provided, where the ADC may include a sample and hold circuitry to sample an analog input signal, and a summation block to iteratively generate a subtraction signal. The subtraction signal may be based on a difference between the analog input signal and a feedback signal. The ADC may further include a common input stage to receive the subtraction signal, and a plurality of comparison and latch circuitries arranged in parallel, where individual ones of the plurality of parallel comparison and latch circuitries may sequentially receive an output of the common input stage.

A calibration circuit and calibration method for a successive approximation register analog-to-digital converter (SAR ADC) are disclosed. The SAR ADC includes a comparator and generates a digital code. The calibration method includes the following steps: (a) creating a voltage difference between two inputs of the comparator, with the absolute value of the voltage difference being smaller than or equal to the absolute value of the voltage corresponding to the least significant bit (LSB) of the digital code; (b) updating a count value according to whether a timer of the SAR ADC issues a time-out signal, the timer issuing the time-out signal after a delay time has elapsed; (c) repeating steps (a) through (b) a predetermined number of times; (d) calculating a probability based on the predetermined number of times and the count value; and (e) adjusting the delay time according to the probability.

A calibration circuit and calibration method for a successive approximation register analog-to-digital converter (SAR ADC) are disclosed. The SAR ADC includes a comparator and generates a digital code. The calibration method includes the following steps: (a) creating a voltage difference between two inputs of the comparator, with the absolute value of the voltage difference being smaller than or equal to the absolute value of the voltage corresponding to the least significant bit (LSB) of the digital code; (b) updating a count value according to whether a timer of the SAR ADC issues a time-out signal, the timer issuing the time-out signal after a delay time has elapsed; (c) repeating steps (a) through (b) a predetermined number of times; (d) calculating a probability based on the predetermined number of times and the count value; and (e) adjusting the delay time according to the probability.

Methods and systems for analog-to-digital conversion using two side branches that may be operated with overlapped timing such that a sampling phase may be overlapped with a previous conversion phase. Some embodiments provide a method of successive approximation A/D converting, comprising sampling a first signal onto a first capacitor that is configured to selectively couple to an analog input of a comparator, sampling a second signal onto capacitors that are coupled to a second analog input of the comparator and configured for charge redistribution successive approximation A/D conversion; carrying out, based on the first signal and the second signal, a charge redistribution successive approximation A/D conversion using the capacitors; and while carrying out the charge redistribution successive approximation A/D conversion based on the first and second signals, sampling a third signal onto a third capacitor that is configured to selectively couple to the analog input of a comparator.

Methods and systems for analog-to-digital conversion using two side branches that may be operated with overlapped timing such that a sampling phase may be overlapped with a previous conversion phase. Some embodiments provide a method of successive approximation A/D converting, comprising sampling a first signal onto a first capacitor that is configured to selectively couple to an analog input of a comparator, sampling a second signal onto capacitors that are coupled to a second analog input of the comparator and configured for charge redistribution successive approximation A/D conversion; carrying out, based on the first signal and the second signal, a charge redistribution successive approximation A/D conversion using the capacitors; and while carrying out the charge redistribution successive approximation A/D conversion based on the first and second signals, sampling a third signal onto a third capacitor that is configured to selectively couple to the analog input of a comparator.

Embodiments of the present invention provide a digital-to-analog conversion circuit, where the digital-to-analog conversion circuit includes a signal amplitude detector and a digital-to-analog converter. When the signal amplitude detector detects a low signal amplitude, a first current module in the digital-to-analog converter operates normally and a second current module in the digital-to-analog converter stops operating. In addition, when stopping operating, the second current module is in a state of a third bias voltage and a fourth bias voltage that are generated by a second bias circuit. When the amplitude detector detects a high signal amplitude subsequently, the second current module resumes normal operation. After operating normally, the second current module switches back to a first bias voltage and a second bias voltage that are generated by a first bias circuit. This reduces a nonlinearity problem caused before a second current module resumes normal operation.

An input sampling stage circuit includes, a precharge buffer, a precharge switch-capacitor circuit, and an input sampling capacitor. The precharge buffer is configured to buffer an input voltage. The precharge switch-capacitor circuit includes a plurality of switches, a first capacitor, and a second capacitor configured such that the first and second capacitors are connected in series during a coarse sampling time and in parallel during a fine sampling time and charge transfer time. The input sampling capacitor is configured to sample the input voltage through the precharge switch-capacitor circuit during the coarse sampling time and sample the input voltage directly during the fine sampling time.