According to one embodiment, an analog-to-digital converter includes: a digital-to-analog converter configured to generate an analog voltage based on a sampled analog signal and a digital code; a clock generator configured to generate a first clock signal; a comparator configured to receive the analog voltage from the digital-to-analog converter, and perform digital output based on the first clock signal; and a controller configured to generate the digital code based on the digital output of the comparator. The clock generator varies a delay period, which is from the end of sampling of the analog signal to the start of generating the first clock signal, for each sampling of the analog signal.

According to one embodiment, an analog-to-digital converter includes: a digital-to-analog converter configured to generate an analog voltage based on a sampled analog signal and a digital code; a clock generator configured to generate a first clock signal; a comparator configured to receive the analog voltage from the digital-to-analog converter, and perform digital output based on the first clock signal; and a controller configured to generate the digital code based on the digital output of the comparator. The clock generator varies a delay period, which is from the end of sampling of the analog signal to the start of generating the first clock signal, for each sampling of the analog signal.

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 ultrasound device including an asynchronous successive approximation analog-to-digital converter and method are provided. The device includes at least one ultrasonic transducer, a plurality of asynchronous successive-approximation-register (SAR) analog-to-digital converters (ADC) coupled to the at least one ultrasonic transducer, at least one asynchronous SAR in the plurality having a sample and hold stage, a digital-to-analog converter (DAC), a comparator, and control circuitry, wherein a DAC update event following at least one bit conversion is synchronized to a corresponding DAC update event of at least one other ADC in the plurality of ADCs.

Systems and methods are provided for enhanced analog-to-digital conversions, particularly by allowing for an ultra-low burst error rate. Analog-to-digital conversion may be applied to an analog input via one or more conversion cycles; and performance related parameter corresponding to the analog-to-digital conversion may be assessed. A digital output corresponding to the analog input may be generated, with the generating being controlled based on the assessing of the performance related parameter. The controlling may include adjusting at least a portion of the digital output. The assessing may include determining, for at least one conversion cycle, whether a performance related condition, corresponding to the performance related parameter, occurs. The determination may be based on an outcome of a matching search performed for that conversion cycle. The determination that the performance related condition occurs may be made when the matching search fails to settle within a corresponding time period.

A method and apparatus are provided for controlling an SAR ADC by generating a first signal to control sampling of an analog input voltage at a DAC, and then generating a second signal to start a successive approximation sequence at a comparator and SAR engine to convert the analog input voltage to an N-bit digital value, where the successive approximation sequence includes a settling phase for each bit of the N-bit digital value and is controlled to synchronously end in response to a first synchronous clock signal, and also includes a comparison phase for each bit of the N-bit digital value to allow for comparison of the analog input voltage to a reference voltage, where each comparison phase is controlled to synchronously start in response to the first synchronous clock signal and asynchronously end in response to a second asynchronous clock signal that is self-generated by the comparator.

An analog to digital converter (ADC) circuit includes a first stage for converting a first analog voltage signal to a first digital signal including a first portion of a digital output signal representing the first analog voltage signal, and generate a first residue voltage based on the first analog voltage signal and the first digital signal. A first amplifier control unit generates a first amplifier start signal based on a second stage ready signal indicating that a second stage is ready to process a second analog voltage signal. In response to the second stage ready signal, a first amplifier generates the second analog voltage signal based on the first residue voltage. The second stage is configured to generate the second stage ready signal, receive the second analog voltage signal, and convert the second analog voltage signal to a second digital signal including a second portion of the digital output signal.

A method and circuit for recovering data from a digital bitstream received from an analog to digital converter includes asynchronously oversampling the digital bitstream at a sampling rate dictated by an estimate of a clock rate of the analog to digital converter and a nominal oversampling factor. The method and circuit also includes calculating widths of bits of the digital bitstream, and calculating a learned oversampling factor using the calculated widths of a predetermined number of bits of the digital bitstream and a minimization function. The method and circuit also includes calculating data bits to be inserted to a digital filter for digestion using the calculated widths of the bits of the digital bitstream and the learned oversampling factor.

An ultrasound device including an asynchronous successive approximation analog-to-digital converter and method are provided. The device includes at least one ultrasonic transducer, a plurality of asynchronous successive-approximation-register (SAR) analog-to-digital converters (ADC) coupled to the at least one ultrasonic transducer, at least one asynchronous SAR in the plurality having a sample and hold stage, a digital-to-analog converter (DAC), a comparator, and control circuitry, wherein a DAC update event following at least one bit conversion is synchronized to a corresponding DAC update event of at least one other ADC in the plurality of ADCs.

Power consumption of a successive-approximation type analog to digital converter is reduced. A system is provided with an analog to digital converter and a power-supply voltage generation unit. In the system provided with the analog to digital converter and the power-supply voltage generation unit, the analog to digital converter compares an analog signal with a reference signal and outputs frequency information indicating the number of times of comparison. Also, in the system, the power-supply voltage generation unit generates power-supply voltage on the basis of the frequency information output by the analog to digital converter and supplies the same to the analog to digital converter.