Аналіз параметрів цифро-аналогового перетворення у прямих цифрових синтезаторах частоти (DDS)
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Файли
Дата
2017
Автори
Мельничук, В.М.
Полікаровських, О.І.
Melnychuk, V.
Polikarovskykh, O.
Назва журналу
Номер ISSN
Назва тому
Видавець
Хмельницький національний університет
Анотація
У даній роботі проаналізовано параметри прямих цифрових синтезаторів частоти (DDS). Побудована
узагальнена модель тестового блоку для аналізу ШПФ сигналу з виходу DDS синтезатора. Розраховано наступні
параметри: сигнал–шум–спотворення (SINAD); співвідношення сигнал–шум (SNR); ефективна кількість бітів
(ENOB). Наведено математичні співвідношення між цими параметрами.
In this paper, the basic parameters of direct digital frequency synthesizers (DDS) are analyzed. A generalized model of the test block for the analysis of the FFT signal from the output of the DDS synthesizer was constructed. The following parameters are calculated: signal–noise–distortion (SINAD); signal–to–noise ratio (SNR); effective number of bits (ENOB). The mathematical relations between these parameters are given. Six popular specifications for quantifying ADC dynamic performance are SINAD (signal–to– noise–and–distortion ratio), ENOB (effective number of bits), SNR (signal–to–noise ratio), THD (total harmonic distortion), THD + N (total harmonic distortion plus noise), and SFDR (spurious free dynamic range). Although most DDS manufacturers have adopted the same definitions for these specifications, some exceptions still exist. Because of their importance in comparing DDSs, it is important not only to understand exactly what is being specified, but the relationships between the specifications. The article analyzes the parameters of digitalanalogue conversion in direct frequency synthesizers (DDS). The mathematical relations between SINAD, SNR and THD are obtained. The results of synthesized signal analysis using these parameters are presented. The signaltonoise ratio (SNR, or sometimes called the SNR without harmonics) is calculated from FFT data in the same way as SINAD, except that the harmonics of the signal are eliminated from the calculation, leaving only the noise ratio. It has been established that only the first 5 harmonics should be excluded, since they dominate, and the following do not have a significant effect. Since SINAD, SNR, ENOB, THD, THD + N, and SFDR are common indicators of dynamic DDS performance, the main task of the study is to establish relationships between these parameters in the context of the manufacturer's specification. The SINAD graph shows that the characteristics of the synthesized signals deteriorate due to highfrequency distortion and are usually constructed for frequencies that are significantly higher than the Nyquist frequency, so we can determine the power of additional components without sampling. Also in work the structural scheme of the test set for analysis of the FFT signal from the output of DDS is analyzed. Using the ADIsimDDS program of the Analog Devices for DDS synthesizers, a typical FFT output for DDS AD9851 with an input clock rate of 95 MHz was investigated.
In this paper, the basic parameters of direct digital frequency synthesizers (DDS) are analyzed. A generalized model of the test block for the analysis of the FFT signal from the output of the DDS synthesizer was constructed. The following parameters are calculated: signal–noise–distortion (SINAD); signal–to–noise ratio (SNR); effective number of bits (ENOB). The mathematical relations between these parameters are given. Six popular specifications for quantifying ADC dynamic performance are SINAD (signal–to– noise–and–distortion ratio), ENOB (effective number of bits), SNR (signal–to–noise ratio), THD (total harmonic distortion), THD + N (total harmonic distortion plus noise), and SFDR (spurious free dynamic range). Although most DDS manufacturers have adopted the same definitions for these specifications, some exceptions still exist. Because of their importance in comparing DDSs, it is important not only to understand exactly what is being specified, but the relationships between the specifications. The article analyzes the parameters of digitalanalogue conversion in direct frequency synthesizers (DDS). The mathematical relations between SINAD, SNR and THD are obtained. The results of synthesized signal analysis using these parameters are presented. The signaltonoise ratio (SNR, or sometimes called the SNR without harmonics) is calculated from FFT data in the same way as SINAD, except that the harmonics of the signal are eliminated from the calculation, leaving only the noise ratio. It has been established that only the first 5 harmonics should be excluded, since they dominate, and the following do not have a significant effect. Since SINAD, SNR, ENOB, THD, THD + N, and SFDR are common indicators of dynamic DDS performance, the main task of the study is to establish relationships between these parameters in the context of the manufacturer's specification. The SINAD graph shows that the characteristics of the synthesized signals deteriorate due to highfrequency distortion and are usually constructed for frequencies that are significantly higher than the Nyquist frequency, so we can determine the power of additional components without sampling. Also in work the structural scheme of the test set for analysis of the FFT signal from the output of DDS is analyzed. Using the ADIsimDDS program of the Analog Devices for DDS synthesizers, a typical FFT output for DDS AD9851 with an input clock rate of 95 MHz was investigated.
Опис
Ключові слова
SINAD, ENOB, SNR, THD, DDS, ШПФ, прямий синтезатор частоти (DDS), direct digital synthesizer, direct digital synthesizer (DDS), direct digital synthesizer
Бібліографічний опис
Мельничук, В.М. Аналіз параметрів цифро-аналогового перетворення у прямих цифрових синтезаторах частоти (DDS) [Текст] / В. М. Мельничук, О. І. Полікаровських // Вісник Хмельницького національного університету. Технічні науки. – 2017. – № 6. – С. 152-158.