Offset calibration for an analog front-end system is provided. The analog front-end system includes a variable-gain amplifier, and the calibration mitigates an offset error of the variable-gain amplifier. Calibration is based on a difference-based estimation technique combined with digital iteration. Difference-based estimation includes measuring different digital output signals from an analog-to-digital converter for different respective gains of the variable-gain amplifier. The digital iteration is utilized to estimate offsets values which converge a digital output difference to a target of zero volts.

A signal processing chain, such as an audio chain, produces an analog output signal from a digital input signal. The signal processing chain is operated by generating a first flag signal for the analog output signal and one or more second flag signals for the digital input signal. Each flag signal assumes a first level or a second level and is set to the first level when a signal from which the flag is generated has a value within an amplitude window. An amount the first flag signal for the analog output signal and the second flag signal for the digital input signal match each other may be calculated for issuing an alert flag which indicates an impaired operation of the signal processing chain.

Approaches provide for calibrating high speed analog-to-digital converters (ADCs). For example, a calibration signal can be applied to parallel ADCs. The output of the parallel ADCs can be analyzed using a gradient-based optimization approach or other such optimization approach to determine optimized gain error calibration data to compensate for gain mismatch in and between individual parallel time-interleaved ADCs and to determine time-offset calibration data to compensate for timing errors in and between individual parallel time-interleaved ADCs. For example, once a calibration signal is applied to an ADC, the output of the ADC can be analyzed to determine a spectrum of the calibration signal. One or more images (e.g., phasors) of the spectrum can be determined and used to determine initial values of the optimization. Thereafter, the optimization approach can be utilized to determine optimized gain error calibration data and optimized time-offset calibration data, which can be stored and/or used to calibrate individual time-interleaved ADCs.

Provided are a sampling clock phase mismatch error estimation method and apparatus, and a storage medium. This sampling clock phase mismatch error estimation method includes: a proportional relation between an estimation operator of a modular square subtraction method corresponding to each frequency interval of multiple frequency intervals and a sampling clock phase mismatch error of a time-interleaved analog to digital converter (TIADC) is acquired; a slope and an offset value of a fitting proportion line segment are counted; and a slope of a proportion line segment corresponding to a real-time estimation frequency is converted, and an offset value corresponding to the real-time estimation frequency is estimated through an interpolation according to a counted slope and a counted offset value, and the actual value of the sampling clock phase mismatch error is estimated according to a converted slope and an offset value estimated through the interpolation.

A digital background calibration circuit including a digital random number generator, an analog-to-digital converter (ADC) and a plurality of switches is provided. The digital random number generator is configured to generate a first digital sequence having a plurality of bits. The ADC includes a plurality of sampling capacitors. The switches receive the first digital sequence and are coupled to the sampling capacitors. During a calibration period, the digital random number generator controls the sampling capacitors via the switches to sample the first digital sequence.

The disclosure includes an analog to digital converter (ADC) comprising a successive approximation register (SAR) unit including a capacitive network to take a sample of an analog signal and a comparator to approximate a digital value based on the analog signal sample via successive comparison. The disclosure also includes a programmable sequencer. The sequencer includes a control memory containing control signal states indicating control signals to operate the SAR unit. The sequencer also includes a program memory including sequence instructions defining a duty cycle for the SAR unit by referencing the control signal states in the control memory. The sequencer also includes a processing circuit to apply control signals according to the control signal states in an order defined by the sequence instructions to manage a sequence of operations at the SAR unit according to the duty cycle to control the ADC.

Provided, among other things, is an apparatus that converts a signal from one sampling domain to another, and which includes: an input line for accepting an input signal and a processing branch. The processing branch includes a branch input coupled to the input line for inputting data samples that are discrete in time and in value, a quadrature downconverter, a first and second lowpass filter, a first and second polynomial interpolator, and a rotation matrix multiplier that provides a phase rotation. The processing branch generates data samples at a sampling interval that differs from the sampling interval associated with the signal provided to the branch input, e.g., with the difference in the sampling intervals depending on fluctuations in the output period of a local oscillator. Certain embodiments include multiple such processing branches, e.g., operating on different frequency bands of the input signal.

An analog-to-digital converter (ADC) includes a digital-to-analog converter (DAC) that has a configurable capacitor array. Based on measurements of differential nonlinearity (DNL) and/or integral nonlinearity (INL) error by an external test computer system, an order for use of the DAC's capacitors can be determined so as to reduce DNL error aggregation, also called INL. The DAC includes a switch matrix that can be programmed by programming data supplied by the test computer system.

A self-calibrating analog-to-digital converter includes a reference signal circuit configured to provide a reference signal, an analog-to-digital converter configured to generate a first digital representation of the reference signal, a dual-slope analog-to-digital converter configured to generate a second digital representation of the reference signal, and a digital engine configured to compare the first digital representation with the second digital representation to obtain a difference and output a calibration signal to the analog-to-digital converter in response to the difference. The reference signal circuit, the analog-to-digital converter, the dual-slop analog-to-digital converter, and digital engine are integrated in an integrated circuit.

It is provided a signal processing system, comprising at least a first, a second and a third digital-to-analog converter (DAC); a processing unit configured for splitting a sampled signal into a first and a second signal corresponding to different frequency portions of the sampled signal, transmitting the first signal to the first DAC, splitting the second signal into a first and a second subsignal and transmitting the first subsignal to the second DAC and the second subsignal to the third DAC, the first subsignal corresponding to the real part of the second signal and the second subsignal corresponding to the imaginary part of the second signal; an IQ mixer configured for mixing an analog output signal of the second DAC and an analog output signal of the third DAC and a combiner for combining an analog output signal of the first DAC and an output signal of the IQ mixer.