【正文】 me, the frequency resolution of the output waveform, frequency and other indicators of accuracy are greatly improved. HP33120 panies such as HP can generate the lOmHz15MHz sine and square wave, but also can produce lOmHz5MHz of arbitrary waveform, but also have the modulation function, can be AM, FM, FSK, Burst, Sweep signal. HP39。后來出現(xiàn)的專用 DDS 芯片極大的推動了 DDS技術(shù)的發(fā)展，但專用 DDS 芯片價格昂貴，且無法實現(xiàn)任意波形輸出，而 CPLD及 FPGA 的發(fā)展為實現(xiàn) DDS 提供了更好的技術(shù)手段。可見，基于 DDS 技術(shù)的波形發(fā)生器能實現(xiàn)高穩(wěn)定度、高精度、高分辨率的波形輸出，具有頻率切換速度快、體積小、價格便宜的特點 ,是一種很有發(fā)展前途的信號源。 此外隨著集成電路制造工藝的逐步提高，通過采用先進的工藝 和低功耗的設(shè)計，數(shù)字集成電路的工作速度已經(jīng)有了很大的提高。并且具有了和 PC 機良好的接口，可以通過 WINDOWS界面的程序進行任意波形的編輯。如 HP 公司的 HP33120 可以產(chǎn)生 lOmHz15MHz 的正弦波和方波， 同時還可以產(chǎn)生 lOmHz5MHz 的任意波形， 還具備調(diào)制功能，可以產(chǎn)生 AM、 FM、 FSK、猝發(fā)、掃頻等信號。它不僅能產(chǎn)生傳統(tǒng)函數(shù)信號發(fā)生器能產(chǎn)生的正弦波、方波、三角波、鋸齒波，還可以產(chǎn)生任意編輯的波形。如這些芯片中大多采用了流水技術(shù)，通過流水技術(shù)的使用，提高了相位累加器的工作頻率，從而使得 DDS 芯片的 輸出頻率可以進一步提高。這些芯片還具有調(diào)制功能。 自 80 年代以來各國都在研制 DDS 產(chǎn)品，并廣泛應(yīng)用于各個領(lǐng)域。為了提高信號源輸出頻率穩(wěn)定度，可以采用晶體振蕩器等方法來解決。緒論 波形發(fā)生器是一種廣泛應(yīng)用于電子電路，自動控制和 科學(xué)實驗等領(lǐng)域的信號源。為了滿足頻率個數(shù)多 的要求，可以采用頻率合成技術(shù)，即通過對頻率進行加減乘除運算，可從一個高穩(wěn)定度和高精確度的標(biāo)準(zhǔn)頻率源，產(chǎn)生大量的具有同一穩(wěn)定度和精確度的不同頻率。其中以AD 公司的產(chǎn)品 比較有代表性。如 AD7008 可以產(chǎn)生正交調(diào)制信號，而 AD9852 也可以產(chǎn)生 FSK、 PSK、線性調(diào)頻以及幅度調(diào)制的信號。通過運用流水技術(shù)在保證相位累加器工作頻率的前提下，相位累加器的字長可以設(shè)計得更長，如 AD9852 的相位累加器達到了 48 位。由于 DDS 的自身特點，還可以很容易的產(chǎn)生一些數(shù)字調(diào)制信號，如 FSK、 PSK 等。 HP 公司的 HP33250 可以產(chǎn)生 1uHz80MHz 的正弦波和方波，產(chǎn)生 1uHz 到 25MHz 的任意波形。 除了在儀器中的應(yīng)用外， DDS 在通信系統(tǒng)和雷達系統(tǒng)中也有很重要的用途?，F(xiàn)在最新的 DDS 芯片工作頻率已經(jīng)可以達到 1GHz，這樣就可以產(chǎn)生頻帶比較寬的輸出信號了。 所以本設(shè)計采用此方案。 FPGA(Field Programmable Gate Array)是目前廣泛采用的一種可編程器件 ,它的應(yīng)用不僅使 數(shù)字電路系統(tǒng)的設(shè)計非常方便 ,并且還大大縮短了系統(tǒng)研制的周期 ,縮小了數(shù)字電路系統(tǒng)的體積和所用芯片的品種， 它的時鐘頻率可達到幾百兆赫茲 ,加上它的靈活性和高可靠性 ,非常適合用于實現(xiàn)波形發(fā)生器的數(shù)字電路部分。s HP33250 can have the 1uHz80MHz sine and square wave, resulting in the 1uHz to 25MHz arbitrary waveform. BK PRECISION pany level 4070A Arbitrary Waveform function generator sine wave and square wave output frequency , frequency resolution 10mHZ. At the same time, also has AM, FM, PM, SSB, BPSK, FSK, Burst, DTMFGeneration and DTMFDetection function. And have a good machine and the PC interface, the interface can process WINDOWS arbitrary waveform editor. In addition to the application of instruments, DDS in munications systems and radar systems are also very important purposes. DDS can be more easily adopted by some of the monly used modulation munication signal, such as: frequency shift keying (FSK), binary phase shift keying (BPSK) and Quadrature Phase Shift Keying (QPSK) and so on. DDS can generate two quadrature phase signal strictly in the quadrature modulator and demodulator in a wide range of applications, this is a good local oscillator. In addition with the integrated circuit manufacturing process of gradual improvement through the use of advanced technology and lowpower design, digital integrated circuits have a speed greatly improved. Now, its latest operating frequency of the DDS chip can reach 1GHz, so that could have a relatively wide frequency band of the output signal. To further enhance the DDS output frequency, resulting in a lot of DDS technology and other methods of frequency synthesis. Such as when the output signal is a highfrequency narrowband signal can be used when the method of filtering expansion mixer output DDS, the DDS can also be used to generate highfrequency spectral characteristics of signals, such as the use of high frequency output of the mirror. Can be seen, based on the DDS waveform generator technology to achieve high stability, high accuracy, highresolution output of the waveform, with frequency switching speed, small size, the characteristics of prices is a very promising signal source. Therefore, the design of this program. In recent years, with programmable logic device (FPGA, CPLD, etc.) a wide range of applications, functions from strength to strength, as well as the continual emergence of fast algorithm, arbitrary waveform generator to the automatic, digital, highprecision of direction. DDS system, the use of early separation of overlapping digital devices, with an operating frequency of the entire circuit system improvement of the separation device used to build the DDS circuit has its own can not overe the shortings, mainly in the electromagic patibility and system frequency. Later, there dedicated DDS chip greatly promoted the development of DDS technology, but dedicated DDS chip is expensive, and can not achieve the arbitrary waveform output, and the CPLD and FPGA development for the realization of DDS technology to provide a better means. FPGA (Field Programmable Gate Array) is widely used as a programmable device, which not only makes the application of digital circuit design is very convenient, but also greatly shorten the system development cycle, reducing the size of the digital circuit system and varieties used in the chip, its clock frequency can reach several hundreds Hz, together with its flexibility and high reliability, very suitable for the realization of the digital waveform generator circuit part. 1 波形發(fā)生器的實現(xiàn)方式 波形發(fā)生器 在生產(chǎn)實踐和科技領(lǐng)域中有著廣泛的應(yīng)用。例如在通信、廣播、電視系統(tǒng)中，都需要射頻（高頻）發(fā)射，這里的射頻波就是載波，把音頻（低頻）、視頻信號或脈沖信號運載出去，就需要能夠產(chǎn)生高頻的振蕩器。這種方式具有電路簡單、實現(xiàn)方便等特點。