外文翻譯---關(guān)于直接數(shù)字頻率合成器-其他專業(yè)-文庫吧資料
2025-01-27 09:22本頁面
【正文】 rement mon to a number of industries. Whether providing agile sources of lowphasenoise variablefrequencies with good spurious performance for munications, or simply generating a frequency stimulus in industrial or biomedical test equipment applications, convenience, pactness, and low cost are important design considerations. Many possibilities for frequency generation are open to a designer, ranging from phaselockedloop (PLL)based techniques for very highfrequency synthesis, to dynamic programming of digitaltoanalog converter (DAC) outputs to generate arbitrary waveforms at lower frequencies. But the DDS technique is rapidly gaining acceptance for solving frequency (or waveform) generation requirements in both munications and industrial applications because singlechip IC devices can generate programmable analog output waveforms simply and with high resolution and accuracy. Furthermore, the continual improvements in both process technolog y and design have resulted in cost and power consumption levels that were previously unthinkably low. For example, the AD9833, a DDSbased programmable waveform generator (Figure 1), operating Figure 1. The AD9833a onechip waveform generator. 2 at V with a 25MHz clock, consumes a maximum power of 30 milliwatts. What are the main benefits of using a DDS? DDS devices like the AD9833 are programmed through a high speed serial peripheralinterface (SPI), and need only an external clock to generate simple sine waves. DDS devices are now available that can generate frequencies from less than 1 Hz up to 400 MHz (based on a 1GHz clock). The benefits of their low power, low cost, and single small package, bined with their inherent excellent performance and the ability to digitally program (and reprogram) the output waveform, make DDS devices an extremely attractive solution— preferable to lessflexible solutions prising aggregations of discrete elements. What kind of outputs can I generate with a typical DDS device? DDS devices are not limited to purely sinusoidal outputs. Figure 2 shows the square, triangular, and sinusoidal outputs available from an AD9833. How does a DDS device create a sine wave? Here’s a breakdown of the i
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