Guzik Technical Enterprises

Valeriy Serebryanskiy

Anatoli B Stein

Alexander M Taratorin

Semen P Volfbeyn

Vladislav Anatolievich Klimov

Igor Tarnikov

Sergey Konshin

Semen P Volfbein

A measurement of phase frequency response of a device under test (DUT), wherein the DUT is characterized by a set of switchable configurations, comprises choosing the steps of a particular configuration of the DUT having nominal parameters as a reference configuration, measuring an amplitude frequency response A(f) and a phase frequency response &#x3d5;(f) of the reference configuration, processing all configurations of the DUT which are different from the reference configuration, one after another, by measuring an amplitude response A(f) of the configuration being processed, calculating a minimum phase difference response &#x394;&#x3d5;(f); and calculating for each configuration, a phase frequency response &#x3d5;(f) of the respective configuration which is being processed, in accordance with &#x3d5;(f)=&#x3d5;(f)+&#x394;&#x3d5;(f).

Phase frequency response measurement method

Repetitive waveforms are processed to produce an averaged replica of the waveforms by first determining a stream of digital samples, with random time shifts of waveform starts relative to the samples. A mutual arrangement of a trigger signal and a following sample over a succession of sampling periods, enables k sections coinciding with segments [k&#xb7;T/K, (k+1)&#xb7;T/K]. K is determined and a distance D between the trigger signal and the following sample is calculated. Second, values of the samples are transformed so that waveforms represented by the samples, are shifted in time by D in relation to the sample positions. The mutual positions of the delayed waveforms and the sampling clock along multiple axes, exactly repeats so that values of the produced samples along the axes coincide. The discreet time delays before averaging avoid frequency component distortions in resulting replicas of the waveforms.

Real-time waveforms averaging with controlled delays

A broadband digitizer for an applied broadband analog input signal SA(t). The digitizer includes a low frequency analog-to-digital converter (LF ADC) channel and a high frequency analog-to-digital converter (HF ADC) channel, an input splitter coupled to respective inputs to the LF ADC channel HF ADC channels, a frequency divider, and a combining unit. Low frequency portions of SA(t) are digitized to digital signal SD[n] in the LF ADC channel and high frequency portions of SA(t) are digitized to digital signal SD[n] in the HF ADC channel. The combining unit combines the digital signals SD[n] and SD[n] to form distortion-reduced SD[n], corresponding to SA(t). Front ends of the LF ADC channel and HF ADC channel reduce level-caused distortions, and the combining unit reduces ADC frequency-caused, time-position-caused, and interpolation-caused distortions.

Broadband digitizer with a low frequency bypass

A real time digital trigger detection channel includes an event detector, a pulse former, a low pass filter, an analog-to-digital converter (ADC) and a Discrete Fourier Transform (DFT) processor coupled in series. The event detector is responsive to an applied input signal and the presence of information requiring digital trigger generation. The pulse former generates a pre-determined, limited length, stable pulse signal which is applied to an anti-aliasing, pulse shaping low pass filter. The resultant shaped pulse signal is converted to a sequence of sample values by the ADC, which in turn are applied to the DFT processor, which in turn calculates a discrete Fourier transform of the output sequence of ADC samples, performing trigger position calculation based on values determined by the DFT processor.

High resolution digital trigger detector

Noise suppression is achieved by averaging a sequence of repetitive waveforms with correction of frequency distortions, establishing a real time processing of signals. First, the waveforms are processed seriatim, and saved in partitioned memory. Then, the memory contents are merged to form an output digital signal. Initially, an input repetitive signal is sampled with a sampling period T, and divided into K sections along the sampling period so that a ksection, where 0&#x2264;k&#x3c;K, coincides with segment [k&#xb7;T/K, (k&#x2212;1)&#xb7;T/K]. Time displacement detection determines relative positions of trigger pulses and edges of the sampling clock, and the number k of a sampling period section where the trigger pulse appears, keeping k unchanged thereafter. A resultant stream of N&#xb7;K samples is transmitted through a lowpass filter, followed by decimation by K, to complete the averaging.

Real-time digital waveform averaging with sub-sampling resolution

A digital equalizer with reduced number of multipliers for correction of the frequency responses of an interleaved analog-to-digital-converter (ADC) is disclosed. An exemplary interleaved analog to digital converter with digital equalization includes at least one composite ADC including M time-interleaved sub-ADCs, and an equalization configuration deploying a Pre-FIR transformers unit, a FIRs assembly unit, and a Post-FIR transformers unit. The FIRs assembly unit includes a finite impulse response (FIR) filter network which is operative pursuant to a Fast Filtering Algorithm as an alternative to a conventional finite impulse response network, enabling a reduction of the number of multipliers compared to conventional FIR filter-based equalization networks for ADCs.

Time interleaved analog to digital converter with digital equalization and a reduced number of multipliers

A method and apparatus for resolving time base-generated errors from sampling scope-based measurements. Mutually synchronized repetitive waveform-to-be-analyzed signals (WAS) and repetitive sinusoidal reference signals (RS) are respectively applied to a first channel and a second channel of a sampling scope. A time base generator applies a sampling signal to the first and second channels. An average sine wave period Tfor k samples of RS is determined, followed by determination of phase error &#x3c6;for each of the k samples, corresponding to phase differences between an ideal sine wave signal and the applied reference sinusoidal signal. Time base error values dfor k samples are calculated from d=&#x3c6;*T&#x3c0;. Error values dcorrect time base errors in the sampling signal, and the WAS is re-sampled at sampling times adjusted by d.

Time base correction method for high accuracy sampling scope-based measurements

A method and system for calibrating a time-interleaved digital to analog converter (DAC) provides equalization of frequency response misalignments in sub-DACs forming the DAC. In a calibration mode, test signals are applied to an DAC and output amplitudes and phases of are measured. From the measured values, complex values of the gains of the respective sub-DACs. h(F) are determined and a specified target frequency response T(F) for a tandem connection equalizer-DAC is determined. For each of a plurality of test frequencies, complex values of equalizer gains Eqare determined from Eq(F)=T(F)/h(F), to form equalizing frequency responses. Sets of equalizing coefficients C(p) pursuant to discrete Fourier transforms on Eq(F). In an operation mode, a digital input signal is transformed input into an equalized digital signal E(n) through use of the sets of equalizing coefficients C(p).

Equalization of sub-DAC frequency response misalignments in time-interleaved high-speed digital to analog converters

A method and apparatus for processing a periodic analog signal using a composite ADC including a time interleaved set of sub-ADCs, to produce a replica signal representative of the analog signal, wherein the replica signal is characterized by suppression of additive noise on the periodic analog signal, and correction of sub-ADC-caused distortions. Streams of samples from the respective sub-ADCs are accumulated separately for respective positions in signal periods of the periodic analog signal to provide sub-replicas. Fourier transforms of the replicas are determined for the different sub-ADCs, and those Fourier transforms are averaged to obtain a mean Fourier transform. Frequency responses of the sub-ADCs are corrected by dividing the mean Fourier transform by the respective sub-ADC frequency responses. An averaged replica of the signal period is obtained by determining an inverse Fourier transform of the corrected mean Fourier transform.

Periodic signal averaging with a time interleaving analog to digital converter

A digital down converter with equalization includes a composite ADC that performs demodulation of a received analog signal, converting the signal into in phase baseband signal and quadrature baseband signal. Equalization is performed to correct for misalignment of the frequency responses of the sub-ADCs in the composite ADC. In a form, ADC output signals are applied to a mixer array to frequency down-shift the digital form of the input signal, followed by digital filtering to effect convolutions of portions of the digital form of the input signal with a set of convolution coefficients determined so that the net processing is mathematically equivalent to down conversion with equalization. In another form, the ADC output signals are directly applied to a digital filter to effect both frequency down-shifting and convolutions, with filter coefficients determined so that the net processing is mathematically equivalent to down conversion with equalization.

Digital down converter with equalization

A digital equalizer with a reduced number of multipliers for correction of the frequency responses of an interleaved ADC is disclosed. An exemplary interleaved analog to digital converter with digital equalization includes a composite ADC including M time interleaved sub-ADC, a demultiplexer, samples repositioning unit, a first PreFIRs transformer, a second PreFIRs transformer, K double buffer FIR filters, a PostFIRs transformer, a samples sequence restoration unit, and a multiplexer, coupled in series and providing an equalized, frequency response-corrected output.

Growing community of inventors

Santa Clara, CA, United States of America

Valeriy Serebryanskiy