An analog-to-digital converter includes a plurality of slave sampler multiplexers responsive to outputs of a master sampler that receives analog signals and whose output ports connect to integrating threshold comparators having capacitive digital-to-analog conversion offset adjustments for forming an analog-to-thermometer code conversion. A calibration state machine receives outputs of each of the integrating threshold comparators to control the capacitive digital-to-analog conversion offset adjustment of every integrating threshold comparator and to control a calibration digital-to analog converter. A thermometer code to binary code logic decoder receives outputs of each of the integrating threshold comparators and outputs digital samples.

An analog-to-digital converter includes a plurality of slave sampler multiplexers responsive to outputs of a master sampler that receives analog signals and whose output ports connect to integrating threshold comparators having capacitive digital-to-analog conversion offset adjustments for forming an analog-to-thermometer code conversion. A calibration state machine receives outputs of each of the integrating threshold comparators to control the capacitive digital-to-analog conversion offset adjustment of every integrating threshold comparator and to control a calibration digital-to analog converter. A thermometer code to binary code logic decoder receives outputs of each of the integrating threshold comparators and outputs digital samples.

An asynchronous successive approximation register analog-to-digital converter (SAR ADC), which utilizes one or more overlapping redundant bits in each digital-to-analog converter (DAC) code word, is operable to generate an indication signal that indicates completion of each comparison step and indicates that an output decision for each comparison step is valid. A timer may be initiated based on the generated indication signal. A timeout signal may be generated that preempts the indication signal and forces a preemptive decision, where the preemptive decision sets one or more remaining bits up to, but not including, the one or more overlapping redundant bits in a corresponding digital-to-analog converter code word for a current comparison step to a particular value. For example, the one or more remaining bits may be set to a value that is derived from a value of a bit that was determined in an immediately preceding decision.

An analog-to-digital converter (ADC) system can sample an input voltage for at least a first conversion into a first N.sub.1-bit digital value and to use the same input voltage sample for at least a second conversion into a second N.sub.2-bit digital value. A difference between a result of the first conversion and a result of the second conversion can be driven toward zero to adjust weights of one or more of the bits to calibrated values for use in one or more subsequent analog-to-digital conversions of subsequent samples of the input voltage. Shuffling, dithering, or the like can help ensure that at least a portion of the decision paths used in the second conversion are different from the decision paths used in the first conversion. Calibration can be performed in the background while the the ADC is converting in a normal mode of operation.

According to one embodiment, a first AD converter converts a first voltage into a first digital signal. A voltage/time conversion circuit acquires a residual corresponding to a difference between the first voltage and a result of having converted the first digital signal into an analog signal and converts the residual into a time signal according to a voltage in a first capacitor. A time/voltage conversion circuit converts the time signal into a voltage signal according to a voltage in a second capacitor. A second AD converter converts the voltage signal into a second digital signal. A digital processing circuit outputs a third digital signal to adjust a current value of first or the second current sources based on the second digital signal.

An analog-to-digital converter includes a plurality of slave sampler multiplexers responsive to outputs of a master sampler that receives analog signals and whose output ports connect to integrating threshold comparators having capacitive digital-to-analog conversion offset adjustments for forming an analog-to-thermometer code conversion. A calibration state machine receives outputs of each of the integrating threshold comparators to control the capacitive digital-to-analog conversion offset adjustment of every integrating threshold comparator and to control a calibration digital-to analog converter. A thermometer code to binary code logic decoder receives outputs of each of the integrating threshold comparators and outputs digital samples.

An analog-to-digital converter (ADC) circuit comprises a digital-to-analog (DAC) circuit including at least N+n weighted circuit components, wherein N and n are positive integers greater than zero, and n is a number of repeat bits of the least significant bit (LSB) of the ADC circuit; a sampling circuit configured to sample an input voltage at an input to the ADC circuit and apply a sampled voltage to the weighted circuit components; a comparator circuit configured to compare an output voltage of the DAC to a specified threshold voltage during a bit trial; and logic circuitry configured to perform bit trials for the at least N+n weighted circuit components and adjust one or more parameters for one or more of N bit trials according to values of the n LSB repeat bits.

A processing speed can be improved while the accuracy of AD conversion is enhanced. An AD converter includes: a higher-order DAC that samples an analog input signal and performs DA conversion corresponding to higher-order bits of a digital output signal; an extension DAC that performs DA conversion to positive and negative polarities on an extension bit for expanding bits of the higher-order DAC; a lower-order DAC that performs DA conversion corresponding to lower-order bits of the digital output signal; a comparator that compares a comparison reference voltage with output voltages of the higher-order DAC, the extension DAC, and the lower-order DAC; and a successive approximation logic that controls successive approximation performed by the higher-order DAC, the extension DAC, and the lower-order DAC based on a comparison result of the comparator and generates the digital output signal.

In an example, a successive approximation register analog-to-digital converter includes a switched capacitor digital-to-analog converter (DAC) first array to sample an input signal and to convert a sample of the input signal to a digital value represented by a plurality of bits, the first array including a first group of capacitors representing at least some of the plurality of bits, a switched capacitor DAC second array including a second group of capacitors representing at least some of the plurality of bits, wherein at least one bit of the plurality of bits represented by the second group of capacitors is represented by at least two capacitors, and wherein each of the two capacitors is configured to be selectively connected to a selected one of at least two reference potentials such that the at least one bit represented by the second group of capacitors is switchable between at least three states.

A digital to analog converter including a current source for providing a master current, a first sub digital to analog converter coupled to the current source which generates a plurality of currents, and a second sub digital to analog converter coupled to at least one of the plurality of currents from the first sub digital to analog converter which generates a second plurality of currents. The digital to analog converter also includes an overlap adjustment circuit coupled with the second sub digital to analog converter which adds current. The digital to analog converter is configured to operate in a first mode for generating a sine wave with a first bit level accuracy and, when in the first mode, the overlap adjustment circuit adds no current. to the second sub digital to analog converter The digital to analog converter is configured to operate in a second mode for generating a ramp wave with a second bit level accuracy and, when in the second mode, the overlap adjustment circuit adds current to the second sub digital to analog converter. When in the second mode, the total current of the second sub digital to analog converter and the overlap converter is greater than one of the plurality of currents generated by the first sub digital to analog converter.