Abstract: A digital RF modulator, an integrated solution that satisfies stringent DOCSIS RF-performancerequirements, takes advantage of modern technologies like high-performance wideband digital-to-analogconversion and CMOS technology scaling. This application note describes the concept and advantages ofa digital quadrature amplitude modulatIOn (QAM) modulator that uses the direct-RF architecture to enablea cable access platform (CCAP) system.
上傳時間： 2013-10-20
上傳用戶：drink！
Abstract: A laser module designer can use a fixed resistor, mechanical pot, digital pot, or a digital-to-analogconverter (DAC) to control the laser driver's modulatIOn and bias currents. The advantages of a programmablemethod (POT or DAC) are that the manufacturing process can be automated and digital control can be applied(e.g., to compensate for temperature). Using POTs can be a more simple approach than a DAC. There can be aslight cost advantage to using a POT, but this is usually not significant relative to other pieces of the design.Using a DAC can offer advantages, including improved linearity (translating to ease of software implementationand ability to hit the required accuracy), increased board density, a wider range of resolutions, a betteroptimization range, ease of use with a negative voltage laser driver, and unit-to-unit consistency
上傳時間： 2013-11-13
上傳用戶：ca05991270
This paper presents a space vector modulatIOn(SVM)-based switching strategy for a three-level neutral point clamped (NPC) converter that is adapted as a STATCOM.
上傳時間： 2013-10-20
上傳用戶：zyt
分析了調幅信號和載波信號之間的相位差與調制信號的極性的對應關系,得出了相敏檢波電路輸出電壓的極性與調制信號的極性有對應關系的結論。為了驗證相敏檢波電路的這一特性,給出3 個電路方案,分別選用理想元件和實際元件,采用Multisim 對其進行仿真實驗,直觀形象地演示了相敏檢波電路的鑒相特性,是傳統(tǒng)的實際操作實驗所不可比擬的。關鍵詞:相敏檢波;鑒相特性;Multisim;電路仿真 Abstract : The corresponding relation between modulatIOn signal polarity and difference phases of amplitudemodulated signal and the carrier signal ,the polarity of phase2sensitive detecting circuit output voltage and the polarity of modulatIOn signal are correspondent . In order to verify this characteristic ,three elect ric circuit s plans are produced ,idea element s and actual element s are selected respectively. Using Multisim to carry on a simulation experiment ,and then demonst rating the phase detecting characteristic of the phase sensitive circuit vividly and directly. Which is t raditional practical experience cannot be com pared.Keywords :phase sensitive detection ;phase2detecting characteristic ;Multisim;circuit simulation
上傳時間： 2013-11-23
上傳用戶：guanhuihong
Abstract: The DS1875 features a pulse-width modulatIOn (PWM) controller that can be used to control aDC-DC converter. The DC-DC converter can then be used to generate the high bias voltages necessaryfor avalanche photodiodes (APDs). This application note describes the operation of a boost converterthat uses the DS1875. Discussion covers the selection of the inductor and switching frequency, and theselection of components that improve the efficiency of the converter. Test data are presented.
上傳時間： 2013-10-26
上傳用戶：lyson
數(shù)字控制的交流調速系統(tǒng)所選用的微處理器、功率器件及產(chǎn)生PWM波的方法是影響交流調速系統(tǒng)性能好壞的直接因素。在介紹了正弦脈寬調制(SPWM)技術的基礎上，設計了一種以8098單片機作為控制器，以智能功率模塊IPM為開關器件的變頻調速系統(tǒng)。通過軟件編程，產(chǎn)生正弦脈沖寬度調制波形來控制絕緣柵雙極晶體管的導通和關斷，從而達到控制異步電動機轉速的目的。實驗結果表明，該系統(tǒng)可調頻率調電壓，穩(wěn)定度高，調速范圍寬，具有較強的實用價值 Abstract: AC variable speed with digital control systems used microprocessors， power devices and generate PWM wave is the direct factors of affecting the performance AC speed regulation system. On the basis of introducing the sinusoidal pulse width modulatIOn (SPWM) technology，this paper designed variable speed system which used 8098 as a controller， intelligent power module IPM as switching device. Through software programming， resulting in sinusoidal pulse width modulatIOn waveform to control the insulated gate bipolar transistor turn on and off， so as to achieve the purpose of speed control of induction motors. Experimental results show that the system can adjust frequency modulatIOn voltage， high stability， wide speed range， has a strong practical value.
標簽： 8098 SPWM 單片機 變頻調速系統(tǒng)
上傳時間： 2013-11-14
上傳用戶：ynwbosss
FEATURES400 MSPS internal clock speedIntegrated 10-bit DAC32-bit tuning wordPhase noise ≤ –120 dBc/Hz @ 1 kHz offset (DAC output)Excellent dynamic performance>75 dB SFDR @ 160 MHz (±100 kHz offset) AOUTSerial I/O control1.8 V power supplySoftware and hardware controlled power-down48-lead TQFP/EP packageSupport for 5 V input levels on most digital inputsPLL REFCLK multiplier (4× to 20×)Internal oscillator; can be driven by a single crystalPhase modulatIOn capabilityMultichip synchronization
上傳時間： 2014-12-04
上傳用戶：axin881314
HT6221發(fā)碼的接收原理及應用 HT6221 是Holtek 公司生產(chǎn)的多功能編碼芯片，采用PPM（Pulse Position modulatIOn）進行編碼
上傳時間： 2014-09-10
上傳用戶：AbuGe
利用TPM2定時器產(chǎn)生一通道語音信號輸出，語音數(shù)據(jù)為PCM格式:PCM的概念脈沖編碼調制(Pulse Code modulatIOn，PCM)是概念上最簡單、理論上最完善的編碼系統(tǒng)，是最早研制成功、使用最為廣泛的編碼系統(tǒng)，但也是數(shù)據(jù)量最大的編碼系統(tǒng)。PCM的編碼原理比較直觀和簡單，它的原理框圖如圖1-1所示。在這個編碼框圖中，它的輸入是模擬聲音信號，它的輸出是PCM樣本。圖中的“防失真濾波器”是一個低通濾波器，用來濾除聲音頻帶以外的信號；“波形編碼器”可暫時理解為“采樣器”，“量化器”可理解為“量化階大小(step-size)”生成器或者稱為“量化間隔”生成器。
上傳時間： 2013-11-21
上傳用戶：DXM35
為了在CDMA系統(tǒng)中更好地應用QDPSK數(shù)字調制方式，在分析四相相對移相（QDPSK)信號調制解調原理的基礎上，設計了一種QDPSK調制解調電路，它包括串并轉換、差分編碼、四相載波產(chǎn)生和選相、相干解調、差分譯碼和并串轉換電路。在MAX+PLUSⅡ軟件平臺上，進行了編譯和波形仿真。綜合后下載到復雜可編程邏輯器件EPM7128SLC84-15中，測試結果表明，調制電路能正確選相，解調電路輸出數(shù)據(jù)與QDPSK調制輸入數(shù)據(jù)完全一致，達到了預期的設計要求。 Abstract: In order to realize the better application of digital modulatIOn mode QDPSK in the CDMA system， a sort of QDPSK modulatIOn-demodulatIOn circuit was designed based on the analysis of QDPSK signal modulatIOn-demodulatIOn principles. It included serial/parallel conversion circuit, differential encoding circuit, four-phase carrier wave produced and phase chosen circuit, coherent demodulatIOn circuit, difference decoding circuit and parallel/serial conversion circuit. And it was compiled and simulated on the MAX+PLUSⅡ software platform,and downloaded into the CPLD of EPM7128SLC84-15.The test result shows that the modulatIOn circuit can exactly choose the phase，and the output data of the demodulator circuit is the same as the input data of the QDPSK modulate. The circuit achieves the prospective requirement of the design.
上傳時間： 2014-01-13
上傳用戶：qoovoop
