The present invention discloses a digital-to-analog conversion apparatus having signal calibration mechanism is provided. A digital-to-analog conversion circuit includes conversion circuits to generate an output analog signal and echo-canceling analog signals. An echo transmission circuit processes an echo-transmitting path to generate an echo signal. An echo calibration circuit generates an output calibration signal and echo-canceling calibration signals according to an input digital circuit through calibration circuits corresponding to the conversion circuits. A calibration parameter calculating circuit generates a plurality of offsets according to an error signal of the echo signal relative to the calibration signals and path information related to the echo calibration circuit. The echo calibration circuit makes response coefficients converge according to the error signal and pseudo-noise transmission path information from the digital-to-analog conversion circuit to the echo transmission circuit, and updates codeword offset table according to the offset.

An estimate of unit current element mismatch error in a digital to analog converter circuit is obtained through a correlation process. Unit current elements of the digital to analog converter circuit are actuated by bits of a thermometer coded signal generated in response to a quantization output signal. A correlation circuit generates the estimates of the unit current element mismatch error from a correlation of a first signal derived from the thermometer coded signal and a second signal derived from the quantization output signal.

A calibration system comprises an actuator circuit comprising a first delay circuit that receives a plurality of data pulses and a second delay circuit that receives the pulses, wherein one of the first and second delay circuits delays the data pulses independently of the other of the first and second delay circuits; a data switch that receives an output of the actuator circuit including delay data signals of the data pulses from the first and second delay circuits and switches and outputs a plurality of local oscillator (LO) signals for output as a controlled LO signal according to control signals of the delay data signals and applied to the data switch. At least one calibration switch receives the output of the actuator circuit and the plurality of LO+ and LO− signals, and outputs a second controlled LO signal output to a sense circuit.

Example embodiments relate to systems and methods for analog-to-digital signal conversion. One embodiment includes a system for analog-to-digital signal conversion. The system includes an analog input signal. The system also includes a digital-to-analog converter configured to generate a reference signal. Further, the system includes an amplifier configured to amplify an error signal that includes a difference between the analog input signal and the reference signal. Additionally, the system includes a level-crossing based sampling circuit that includes a first comparator configured to compare the error signal with respect to a first reference level, and a second comparator configured to compare the error signal with respect to a second reference level, thereby generating event-based reset signals corresponding to a plurality of sampling instances in order to reset the digital-to-analog converter. Yet further, the system includes a trigger circuit configured to generate reset signals asynchronous to the event-based reset signals.

An analog-to-digital conversion circuit includes; a first analog-to-digital converter (ADC), a second ADC and a third ADC collectively configured to perform conversion operations according to a time-interleaving technique, and a timing calibration circuit configured to calculate correlation values and determine differences between the correlation values using first samples generated by the first ADC, second samples generated by the second ADC, and third samples generated by the third ADC during sampling periods, wherein the timing calibration circuit is further configured to control a phase of a clock signal applied to the second ADC in response to a change in absolute value related to the differences generated during the sampling periods.

A calibration circuit, including: a first analog-to-digital converter (ADC) configured to sample a nonlinear reference signal continuously at an equidistant sampling rate to generate a reference sampled signal; a trigger timer configured to generate trigger signals; a second ADC configured to sample a point of each of the nonlinear reference signal and repeated versions of the nonlinear reference signal in response to the respective trigger signals at equidistantly increasing delays, to generate a device-under-test (DUT) sampled voltage; and processing circuitry configured to estimate a differential nonlinearity (DNL) of the DUT sampled signal, estimate a DNL of the reference sampled signal, and compare the estimated DNL of the DUT sampled signal with the estimated DNL of the reference sampled signal, to generate a DNL performance indication signal of the second ADC.

An N-channel interleaved Analog-to-Digital Converter (ADC) has a variable delay added to each ADC's input sampling clock. The variable delays are each programmed by a Successive-Approximation-Register (SAR) during calibration to minimize timing skews between channels. In each channel the ADC output is filtered, and a product derivative correlator generates a product derivative factor for correlation to two adjacent ADC channels. A matrix processor arranges the product derivative factors from the product derivative correlators into a matrix that is multiplied by a correlation matrix. The correlation matrix is a constant generated from an N×N shift matrix. The matrix processor outputs a sign-bit vector. Each bit in the sign-bit vector determines when tested SAR bits are set or cleared to adjust a channel's variable delay. Sampling clock and component timing skews are reduced to one LSB among all N channels.

An N-channel interleaved Analog-to-Digital Converter (ADC) has a variable delay added to each ADC's input sampling clock. The variable delays are each programmed by a Successive-Approximation-Register (SAR) during calibration to minimize timing skews between channels. Each channel receives a sampling clock with a different phase delay. The sampling clocks are overlapping multi-phase clocks rather than non-overlapping. Overlapping the multi-phase clocks allows the sampling pulse width to be enlarged, providing more time for the sampling switch to remain open and allow analog voltages to equalize through the sampling switch. Higher sampling-clock frequencies are possible than when non-overlapping clocks are used. The sampling clock is boosted in voltage by a bootstrap driver to increase the gate voltage on the sampling switch, reducing the ON resistance. Sampling clock and component timing skews are reduced to one LSB among all N channels.

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.

A current digital-to-analog converter may be used in a system for measuring temperature of a thermistor, with mismatch reduction techniques applied to digital-to-analog converter elements of the digital-to-analog converter in order to maximize accuracy and precisions of the temperature measurement.