An ADC is disclosed. The ADC includes a SAR logic circuit, a DAC, a comparator, and a voltage generator. The voltage generator includes a first switch connected to the comparator configured to selectively connect a second input terminal of the comparator to a reference voltage, a capacitor connected to the second input terminal of the comparator, and a second switch connected to the capacitor and selectively connected to either of a ground voltage and the reference voltage. The second switch is configured to selectively connect the capacitor to either of the ground voltage and the reference voltage, and the SAR logic circuit is further configured to receive the comparator output voltage, and to generate a digital input word for the DAC based on one or more comparator output voltages received from the comparator.

A switched capacitor circuit, including a metal-oxide-semiconductor field-effect transistor-based switch comprising: a first metal-oxide-semiconductor field-effect transistor having a gate, a source and a drain, wherein the source is connected to a first node and the drain is connected to a second node or wherein the drain is connected to the first node and the source is connected to the second node; a second metal-oxide-semiconductor field-effect transistor having a gate, a source and a drain, wherein the source is connected to the drain and the source and the drain are together connected to the second node; a first capacitor connected between the first node and a third node; and a second capacitor connected between the second node and the third node.

An ADC, including a DAC which receives an analog input voltage and a digital input word from SAR logic, and generates a first voltage based on the analog input voltage and the digital word. The ADC also includes a comparator, which receives the first voltage and a reference voltage, and generates a second voltage based on the first voltage and on the reference voltage. The second voltage has a value corresponding with a sign of the difference between the first voltage and the reference voltage. The ADC also includes the SAR logic circuit which receives the second voltage from the comparator. The SAR logic generates a digital output word based on a second voltages received from the comparator. A difference between the minimum input voltage on the maximum input voltage is substantially equal to two times a difference between reference voltage and the minimum input voltage.

An image sensing system and methods for operating the same are disclosed. An image sensing system includes a plurality of pixel circuits, a multiplexer configured to select one of the pixel circuit and provide analog pixel data without sampling, and a successive approximation register (SAR) analog-to-digital converter (ADC) configured to convert the analog pixel data into digital data. The SAR ADC includes a capacitive digital-to-analog converter (CDAC) configured to convert contents of the SAR into a corresponding analog signal for comparison, by a comparator, with the analog pixel data. The CDAC includes a two-dimensional array of circuit elements. A control circuit in the image sensing system is configured to cause random ones of the circuit elements of the CDAC to be selected for generation of the corresponding analog signal and add a dithering signal so a CDAC output and shuffle a multiplexer switch sequence to improve fixed pattern noise.

An ADC, including a DAC which receives an analog input voltage and a digital input word from SAR logic, and generates a first voltage based on the analog input voltage and the digital word. The ADC also includes a comparator, which receives the first voltage and a reference voltage, and generates a second voltage based on the first voltage and on the reference voltage. The second voltage has a value corresponding with a sign of the difference between the first voltage and the reference voltage. The ADC also includes the SAR logic circuit which receives the second voltage from the comparator. The SAR logic generates a digital output word based on a second voltages received from the comparator. A difference between the minimum input voltage on the maximum input voltage is substantially equal to two times a difference between reference voltage and the minimum input voltage.

An ADC is disclosed. The ADC includes a SAR logic circuit, a DAC, a comparator, and a voltage generator. The voltage generator includes a first switch connected to the comparator configured to selectively connect a second input terminal of the comparator to a reference voltage, a capacitor connected to the second input terminal of the comparator, and a second switch connected to the capacitor and selectively connected to either of a ground voltage and the reference voltage. The second switch is configured to selectively connect the capacitor to either of the ground voltage and the reference voltage, and the SAR logic circuit is further configured to receive the comparator output voltage, and to generate a digital input word for the DAC based on one or more comparator output voltages received from the comparator.

An all-digital operational amplifier architecture, that does not have the constraint of maintaining devices in their saturation region, can leverage the high speed achievable by deeply scaled technology to replace traditional linear current referenced continuous-time operational amplifier circuits with CMOS-like dynamic circuits that require no referencing structure, have no static power consumption, and are compatible with ultra-low supply voltages. Techniques are described to replace analog continuous-time linear operational amplifier input and output stages by a discrete-time comparator circuit, e.g., CMOS-style, and a switched capacitor charge pump circuit, respectively.

A pipelined analog-to-digital converter (ADC) using a multiplying digital-to-analog converter (MDAC) and two sub-range analog-to-digital converters (sub-range ADCs) is disclosed. The MDAC samples an analog input and performs multiplication on the sampled analog input based on control bits. The first sub-range ADC provides the MDAC with the control bits. The second sub-range ADC is coupled to the MDAC for conversion of a multiplied signal output from the MDAC. The first sub-range ADC samples the analog input to generate the control bits for the MDAC as well as pre-estimated bits for the second sub-range ADC. The second sub-range ADC operates based on the pre-estimated bits and thereby a first section of digital bits are generated by the second sub-range ADC. A second section of digital bits are provided by the first sub-range ADC. The first and second sections of digital bits represent the analog input

An analog-to-digital converter (ADC) includes a digital-to-analog converter (DAC) and a comparator having a first input coupled to receive an output voltage of the DAC, a second input, and a comparison output. The ADC also includes successive-approximation-register (SAR) circuitry having an input to receive the comparison output, and an output to provide an uncalibrated digital value. The DAC includes a Most Significant Bits (MSBs) sub-DAC including a set of MSB DAC elements and a Least Significant Bits (LSBs) sub-DAC including a set of LSB DAC elements. The ADC also includes calibration circuitry which receives the uncalibrated digital value and applies one or more calibration values to the uncalibrated digital value to obtain a calibrated digital value. The calibration circuitry obtains a calibration value for each MSB DAC element using the set of LSB DAC elements, the termination element, and at least one of the one or more redundant DAC elements.

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.