Systems and methods are disclosed for improving data channel design by applying transform domain analytics to more reliably extract user data from a signal. In certain embodiments, an apparatus may comprise a channel circuit configured to receive an analog signal at an input of the channel circuit, and sample the analog signal to obtain a set of signal samples. The channel circuit may further apply a filter configured to perform transform domain analysis to the set of signal samples to generate a first subset of samples, the first subset including fewer transitions and having a higher signal to noise ratio (SNR) than the set of signal samples. The channel circuit may detect first bit transform domain representation values from the first subset, and determine channel bit values encoded in the analog signal based on the set of signal samples and using the first bit transform domain representation values detected from the first subset as side information.

Systems and methods are disclosed for improving data channel design by applying transform domain analytics to more reliably extract user data from a signal. In certain embodiments, an apparatus may comprise a channel circuit configured to receive an analog signal at an input of the channel circuit, and sample the analog signal to obtain a set of signal samples. The channel circuit may further apply a filter configured to perform transform domain analysis to the set of signal samples to generate a first subset of samples, the first subset including fewer transitions and having a higher signal to noise ratio (SNR) than the set of signal samples. The channel circuit may detect first bit transform domain representation values from the first subset, and determine channel bit values encoded in the analog signal based on the set of signal samples and using the first bit transform domain representation values detected from the first subset as side information.

Techniques for testing circuits, such as converter circuits, such as digital-to-analog converter circuits (DACs), are described. A digital signal processor (DSP) can generate a waveform, such as sine wave, and apply the sine wave to the circuit under test, e.g., a DAC. The DAC can generate an output and the DSP can regenerate the waveform and determine an accuracy of the DAC such as to determine whether the DAC meets one or more specified criteria. In some example implementations, the tests can be performed using variable voltage amplitude segments.

A non-linearity correction circuit includes a non-linearity coefficient estimation circuit. The non-linearity coefficient estimation circuit includes a data capture circuit, a non-linearity term generation circuit, a time-to-frequency conversion circuit, a bin identification circuit, a residual non-linearity conversion circuit, and a non-linearity coefficient generation circuit. The non-linearity term generation circuit is coupled to the data capture circuit. The time-to-frequency conversion circuit is coupled to the data capture circuit and the non-linearity term generation circuit. The bin identification circuit is coupled to the time-to-frequency conversion circuit. The residual non-linearity conversion circuit is coupled to the bin identification circuit. The non-linearity coefficient generation circuit is coupled to the bin identification circuit and the residual non-linearity conversion circuit.

A method for non-linearity correction includes receiving a first output signal from a data signal path containing a first analog-to-digital converter and receiving a second output signal from a second analog-to-digital converter. The method also includes generating first non-linearity coefficients using the first output signal and generating second non-linearity coefficients using the first and second output signals. The method further includes applying, by a non-linearity corrector in the data signal path, the first and second non-linearity coefficients to compensate for non-linearity components in a digitized signal output from the first analog-to-digital converter to generate a corrected digitized signal.

Provided are an apparatus and a method for measuring a frequency of a broadband signal by using low-speed ADCs having sub-Nyquist sampling rates. A plurality of channels each including a low-speed ADC having a sub-Nyquist sampling rate (e.g. sampling frequency from several MHz to hundreds of MHz) are provided, and the frequency of an input signal corresponding to a combination of frequencies calculated through the respective channels is estimated. Therefore, as the number of channels increases, the range of measurable frequencies may be extended.

Systems and methods are disclosed for improving data channel design by applying transform domain analytics to more reliably extract user data from a signal. In certain embodiments, an apparatus may comprise a channel circuit configured to receive an analog signal at an input of the channel circuit, and sample the analog signal to obtain a set of signal samples. The channel circuit may further apply a filter configured to perform transform domain analysis to the set of signal samples to generate a first subset of samples, the first subset including fewer transitions and having a higher signal to noise ratio (SNR) than the set of signal samples. The channel circuit may detect first bit transform domain representation values from the first subset, and determine channel bit values encoded in the analog signal based on the set of signal samples and using the first bit transform domain representation values detected from the first subset as side information.

Methods and apparatus for determining non-linearity in analog-to-digital converters are disclosed. An example apparatus includes a signal interface to receive an output of an analog-to-digital converter (ADC), the output corresponding to a periodic signal transmitted to the ADC; a signal transformer to determine at least one of a harmonic phase or a harmonic amplitude corresponding to the output; and an integral non-linearity (INL) term calculator to determine the INL of the ADC based on a characteristic of the periodic signal and the at least one of the harmonic phase or the harmonic amplitude.

Provided are an apparatus and a method for measuring a frequency of a broadband signal by using low-speed ADCs having sub-Nyquist sampling rates. A plurality of channels each including a low-speed ADC having a sub-Nyquist sampling rate (e.g. sampling frequency from several MHz to hundreds of MHz) are provided, and the frequency of an input signal corresponding to a combination of frequencies calculated through the respective channels is estimated. Therefore, as the number of channels increases, the range of measurable frequencies may be extended.

Disclosed examples include a method and automated test system for testing an ADC. The method includes computing an ADC noise value based on a first set of data values sampled while the ADC input terminals are shorted, computing a first system noise value based on a second set of data values sampled while a test circuit signal source applies zero volts to the ADC through a signal chain, computing a signal chain noise value based on the first system noise value and the ADC noise value, computing a measured SNR value based on a third set of data values sampled while the test circuit signal source applies a non-zero source voltage signal to the signal chain, computing a second system noise value based on the measured SNR value, and computing an ADC SNR value based on the second system noise value and the signal chain noise value.