Abstract: A measurement apparatus for measuring a characteristic (for example, EVM) of a device under measurement provided with a quadrature modulator or a quadrature demodulator is provided. The measurement apparatus includes an I-Q error measuring section that measures a frequency characteristic of an I-Q error of the device under measurement, and an error amount calculating section that calculates, based on the frequency characteristic of the I-Q error, an error amount observed when the device under measurement is supplied with a predetermined signal.

Abstract: Provided is a measuring apparatus which measures a quadrature modulator, including a supplying section supplying the quadrature modulator with a reference I signal having a predetermined frequency and a reference Q signal whose phase is shifted by 90 degrees from the reference I signal, an extracting section extracting, from a modulation signal output from the quadrature modulator by applying quadrature modulation to the reference IQ signals, a main signal component as the reference IQ signals modulated, and an image signal component occurring at a position symmetric to the modulated reference IQ signals with respect to the carrier signal, and a measurement value calculating section calculating at least one of a carrier phase error and amplitude error which occur between I signal and Q signal sides of the quadrature modulator, and a skew between IQ signals of the quadrature modulator, based on the main signal component and image signal component.

Abstract: A measurement apparatus that measures at least one of phase error and gain error between I and Q of a quadrature modulator, comprising a supplying section that shifts a reference I signal corresponding to an I component in an IQ signal causing a tone signal and/or a reference Q signal corresponding to a Q component in the IQ signal to have a time difference therebetween, and supplies the resulting signals to the quadrature modulator; and a calculating section that calculates at least one of the phase error and the gain error, based on an I-signal frequency component corresponding to a tone signal in a modulated signal output from the quadrature modulator in response to the reference I signal being supplied thereto and a Q-signal frequency component corresponding to a tone signal in a modulated signal output from the quadrature modulator in response to the reference Q signal being supplied thereto.

Abstract: Provided is a test apparatus that tests a device under test that outputs a plurality of modulated signals modulated with carrier signals having frequencies identical to each other, including a synthesizing section that synthesizes the plurality of modulated signals to output a synthesized signal; an AD converting section that samples the synthesized signal to output a digital signal corresponding to the synthesized signal; and a judging section that judges acceptability of the plurality of modulated signals output by the device under test, based on the digital signal.

Abstract: An AD converting apparatus converts an analog input signal into a digital output signal. The apparatus includes a plurality of AD converters that are supplied with sampling clocks differing from each other by a prescribed phase and that each output an individual signal obtained by digitizing the input signal according to the sampling clock supplied thereto, a common compensating section that commonly compensates for prescribed common non-linear distortion in the individual signals, and a plurality of individual compensating sections that each individually compensate for individual non-linear distortion in a corresponding one of the individual signals. The individual non-linear distortion is obtained as a ratio between the non-linear distortion and the common non-linear distortion in each individual signal. The apparatus further includes a combining section that combines the individual signals to generate the output signal.

Abstract: Provided is a measurement apparatus that measures a characteristic of an AD converter, comprising a signal supplying section that supplies the AD converter with an analog input signal having a prescribed waveform; an acquiring section that acquires a digital output signal output by the AD converter as a result of sampling the analog input signal; a measured histogram generating section that generates a histogram of the digital output signal; and a range calculating section that calculates at least one of an analog value corresponding to a lower limit and an analog value corresponding to an upper limit of a prescribed digital range, based on at least one of (i) a frequency corresponding to digital values, in a measured histogram obtained by measuring the digital output signal, that are less than or equal to the digital range and (ii) a frequency corresponding to digital values in the measured histogram that are greater than or equal to the digital range.

Abstract: Provided is a signal output control section that inputs to a digitizer a reference signal whose frequency changes at each prescribed measurement cycle; a data extracting section that extracts a number of pieces of data corresponding to an integer multiple of a period of the reference signal in each measurement cycle, from pieces of data of a reference digital signal output by the digitizer according to the reference signal that come after a prescribed wait interval has passed since an initiation timing of each measurement cycle; a distortion identifying section that calculates the non-linear distortion caused by the digitizer for each frequency of the reference signal, based on the data in each measurement cycle extracted by the data extracting section; and a distortion calculating section that calculates the non-linear distortion caused by the digitizer when the analog signal input to the digitizer has a frequency that differs from any of the plurality of frequencies at which the reference signal transitions

Abstract: Provided is a reference data converting section that rearranges each of a plurality of frequency components along the frequency axis such that (i) a fundamental wave component and harmonic wave components of a reference digital signal are within a first Nyquist region of a spectrum of the reference digital signal and (ii) image components of the fundamental wave component and the harmonic wave components are within a second Nyquist region of the spectrum; and a distortion detecting section that detects the non-linear distortion of the reference digital signal caused by each harmonic wave component, based on each harmonic wave component having a prescribed order number in the spectrum in which each frequency component has been rearranged by the reference data converting section.

Abstract: Provided is an AD converting apparatus that converts an analog input signal into a digital output signal, comprising a plurality of AD converters supplied with sampling clocks differing from each other by prescribed phase amounts, each AD converter outputting an individual signal obtained by digitizing the input signal according to the supplied sampling clock; a plurality of amplitude-dependent characteristic correcting sections that are provided to correspond to the plurality of AD converters, each amplitude-dependent characteristic correcting section generating a corrected individual signal by correcting the individual signal output by the corresponding AD converter using a correction factor corresponding to an amplitude of the individual signal; and a combining section that generates the output signal by combining a plurality of the corrected individual signals.

Abstract: Provided is a signal processing apparatus for compensating for a non-linear distortion of a digital signal, including: an analysis signal generating section that converts the digital signal into a analysis signal of a complex number, using a digital filter; and a compensation section that compensates for the analysis signal, using a compensation coefficient of a complex number corresponding to the non-linear distortion, where the digital filter divides data of the digital signal into “n” data sequences, assigns (n*L+k)th data of the digital signal to a k-th data sequence, performs filtering on each of the data sequences using a same filter coefficient, and combines each of the data sequences after the filtering, thereby generating an imaginary number portion of the analysis signal, where “n” is an integer equal to or greater than 2, L=0, 1, . . . , and k=1, 2, . . . , n.

Abstract: Provided is an AD converting apparatus that converts an analog input signal into a digital output signal, comprising a plurality of AD converters supplied with sampling clocks differing from each other by prescribed phase amounts, each AD converter outputting an individual signal obtained by digitizing the input signal according to the supplied sampling clock; a plurality of amplitude-dependent characteristic correcting sections that are provided to correspond to the plurality of AD converters, each amplitude-dependent characteristic correcting section generating a corrected individual signal by correcting the individual signal output by the corresponding AD converter using a correction factor corresponding to an amplitude of the individual signal; and a combining section that generates the output signal by combining a plurality of the corrected individual signals.

Abstract: Provided is an AD converting apparatus that converts an analog input signal into a digital output signal, comprising a plurality of AD converters that are supplied with sampling clocks differing from each other by a prescribed phase, and that each output an individual signal obtained by digitizing the input signal according to the sampling clock supplied thereto; a common compensating section that commonly compensates for prescribed common non-linear distortion in the individual signals; a plurality of individual compensating sections that each individually compensate for individual non-linear distortion in a corresponding one of the individual signals, the individual non-linear distortion obtained as a ratio between the non-linear distortion and the common non-linear distortion in each individual signal; and a combining section that combines the individual signals to generate the output signal.

Abstract: An analog-to-digital conversion apparatus includes an interleaving section that aligns the digital data respectively output from a plurality of analog-to-digital conversion sections and generates a data sequence, and a correction arithmetic section that corrects a data value error caused by errors of frequency characteristics of the plurality of analog-to-digital conversion sections, in which the correction arithmetic section includes: a data partitioning section that generates a plurality of partition data by partitioning the data sequence, a data inserting section that inserts data with data value zero at the head or end of each of the partition data by a predetermined insertion data number to sequentially output these data, an arithmetic section that sequentially outputs data after correction made by sequentially performing correction arithmetic on the partition data, and a data connecting section that adds sequentially connects the data after correction and the data after correction following the data aft

Abstract: Provided is a measuring apparatus which measures a quadrature modulator, including a supplying section supplying the quadrature modulator with a reference I signal having a predetermined frequency and a reference Q signal whose phase is shifted by 90 degrees from the reference I signal, an extracting section extracting, from a modulation signal output from the quadrature modulator by applying quadrature modulation to the reference IQ signals, a main signal component as the reference IQ signals modulated, and an image signal component occurring at a position symmetric to the modulated reference IQ signals with respect to the carrier signal, and a measurement value calculating section calculating at least one of a carrier phase error and amplitude error which occur between I signal and Q signal sides of the quadrature modulator, and a skew between IQ signals of the quadrature modulator, based on the main signal component and image signal component.

Abstract: There is provided a test apparatus for testing a device under test, which includes a plurality of drivers which output signals to the device under test, an output control section which controls the plurality of drivers to output a plurality of signals respectively, a calculating section which calculates skews of the plurality of signals output from the plurality of drivers respectively, based on a combination signal obtained by combining the plurality of signals, and an adjusting section which adjusts the timings to output signals to be output from the plurality of drivers, based on the skews.

Abstract: Provided is a test apparatus that tests a device under test that outputs a plurality of modulated signals modulated with carrier signals having frequencies identical to each other, including a synthesizing section that synthesizes the plurality of modulated signals to output a synthesized signal; an AD converting section that samples the synthesized signal to output a digital signal corresponding to the synthesized signal; and a judging section that judges acceptability of the plurality of modulated signals output by the device under test, based on the digital signal.

Abstract: An analog-to-digital conversion apparatus includes an interleaving unit operable to align the digital data respectively output from the plurality of analog-to-digital conversion units; and a correction arithmetic unit operable to correct a data value error of a data sequence caused by an error of a frequency characteristic for each of the plurality of analog-to-digital conversion units. The correction arithmetic unit includes a data partitioning unit that partitions the data sequence into a plurality of partition data having a predetermined partition data number and respectively generates the partition data; an arithmetic unit that sequentially acquires the partition data and sequentially outputs data after correction made by sequentially performing correction arithmetic; and a data connecting unit that removes either of the duplicated data according to each partition data or the duplicated data and sequentially connects the data after correction.

Abstract: An analog-to-digital conversion apparatus includes an interleaving section that aligns the digital data respectively output from a plurality of analog-to-digital conversion sections and generates a data sequence, and a correction arithmetic section that corrects a data value error caused by errors of frequency characteristics of the plurality of analog-to-digital conversion sections, in which the correction arithmetic section includes: a data partitioning section that generates a plurality of partition data by partitioning the data sequence, a data inserting section that inserts data with data value zero at the head or end of each of the partition data by a predetermined insertion data number to sequentially output these data, an arithmetic section that sequentially outputs data after correction made by sequentially performing correction arithmetic on the partition data, and a data connecting section that adds sequentially connects the data after correction and the data after correction following the data aft

Abstract: A digitizer module comprises an AD converter for sampling a pair of analog signals at a predetermined time interval and converting into a first and second digital signals respectively, a second signal frequency component calculating unit for calculating a second signal frequency component representing a component of each frequency of the second digital signal on the basis of the second digital signal, a skew frequency component calculating unit for calculating a skew frequency component representing a phase error of each frequency of the second digital signal corresponding to the first digital signal on the basis of a skew of a timing with which the pair of analog signals are sampled by the AD converter and a second signal frequency component correcting unit for correcting the second signal frequency component on the basis of the skew frequency component.

Abstract: A digitizer module comprises an AD converter for sampling a pair of analog signals at a predetermined time interval and converting into a first and second digital signals respectively, a second signal frequency component calculating unit for calculating a second signal frequency component representing a component of each frequency of the second digital signal on the basis of the second digital signal, a skew frequency component calculating unit for calculating a skew frequency component representing a phase error of each frequency of the second digital signal corresponding to the first digital signal on the basis of a skew of a timing with which the pair of analog signals are sampled by the AD converter and a second signal frequency component correcting unit for correcting the second signal frequency component on the basis of the skew frequency component.