分析了調(diào)幅信號(hào)和載波信號(hào)之間的相位差與調(diào)制信號(hào)的極性的對(duì)應(yīng)關(guān)系,得出了相敏檢波電路輸出電壓的極性與調(diào)制信號(hào)的極性有對(duì)應(yīng)關(guān)系的結(jié)論。為了驗(yàn)證相敏檢波電路的這一特性,給出3 個(gè)電路方案,分別選用理想元件和實(shí)際元件,采用Multisim 對(duì)其進(jìn)行仿真實(shí)驗(yàn),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(shí)際操作實(shí)驗(yàn)所不可比擬的。關(guān)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(shí)間： 2013-11-23
上傳用戶：guanhuihong
Radio Frequency Integrated Circuit Design I enjoyed reading this book for a number of reasons. One reason is that itaddresses high-speed analog design in the context of microwave issues. This isan advanced-level book, which should follow courses in basic circuits andtransmission lines. Most analog integrated circuit designers in the past workedon applications at low enough frequency that microwave issues did not arise.As a consequence, they were adept at lumped parameter circuits and often notcomfortable with circuits where waves travel in space. However, in order todesign radio frequency (RF) communications integrated circuits (IC) in thegigahertz range, one must deal with transmission lines at chip interfaces andwhere interconnections on chip are far apart. Also, impedance matching isaddressed, which is a topic that arises most often in microwave circuits. In mycareer, there has been a gap in comprehension between analog low-frequencydesigners and microwave designers. Often, similar issues were dealt with in twodifferent languages. Although this book is more firmly based in lumped-elementanalog circuit design, it is nice to see that microwave knowledge is brought inwhere necessary.Too many analog circuit books in the past have concentrated first on thecircuit side rather than on basic theory behind their application in communications.The circuits usually used have evolved through experience, without asatisfying intellectual theme in describing them. Why a given circuit works bestcan be subtle, and often these circuits are chosen only through experience. Forthis reason, I am happy that the book begins first with topics that require anintellectual approach—noise, linearity and filtering, and technology issues. Iam particularly happy with how linearity is introduced (power series). In therest of the book it is THEN shown, with specific circuits and numerical examples,how linearity and noise issues arise.
標(biāo)簽： Rogers Radio John Freq
上傳時(shí)間： 2014-12-23
上傳用戶：han_zh
Abstract: We can apply a BiCMOS integrated circuit with only resistors and no transistors to solve adifficult design problem. The mythically perfect operational amplifier's gain and temperature coefficient aredependent on external resistor values. Maxim precision resistor arrays are manufactured together on asingle die and THEN automatically trimmed, to ensure close ratio matching. This guarantees that theoperational amplifier (op amp) gain and temperature coefficient are predictable and reliable, even withlarge production volumes.
上傳時(shí)間： 2014-11-30
上傳用戶：ynzfm
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.
標(biāo)簽： DC-DC 如何設(shè)計(jì) 高效率 轉(zhuǎn)換器
上傳時(shí)間： 2013-10-26
上傳用戶：lyson
鎖定放大是微弱信號(hào)檢測(cè)的重要手段。基于相關(guān)檢測(cè)理論，利用開(kāi)關(guān)電容的開(kāi)關(guān)實(shí)現(xiàn)鎖定放大器中乘法器的功能，提出開(kāi)關(guān)電容和積分器相結(jié)合以實(shí)現(xiàn)相關(guān)檢測(cè)的方法，并設(shè)計(jì)出一種鎖定放大器。該鎖定放大器將微弱信號(hào)轉(zhuǎn)化為與之相關(guān)的方波，通過(guò)后續(xù)電路得到正比于被測(cè)信號(hào)的直流電平，為后續(xù)采集處理提供方便。測(cè)量數(shù)據(jù)表明鎖定放大器前級(jí)可將10-6 A的電流轉(zhuǎn)換為10-1 V的電壓，后級(jí)通過(guò)帶通濾波器級(jí)聯(lián)可將信號(hào)放大1×105倍。該方法在降低噪聲的同時(shí)，可對(duì)微弱信號(hào)進(jìn)行放大，線性度較高、穩(wěn)定性較好。 Abstract: Lock-in Amplifying（LIA）is one of important means for weak signal detection. Based on cross-correlation detection theory， switch in the swithched capacitor was used as multiplier of LIA， and a new method of correlation detection was proposed combining swithched capacitor with integrator. A kind of LIA was designed which can convert the weak signal to square-wave， THEN DC proportional to measured signal was obtained through follow-up conditioning circuit， providing convenience for signal acquisition and processing. The measured data shows that the electric current（10-6 A） can be changed into voltage（10-1 V） by LIA， and the signal is magnified 1×105 times by cascade band-pass filter. The noise is suppressed and the weak signal is amplified. It has the advantages of good linearity and stability.
標(biāo)簽： 開(kāi)關(guān)電容 鎖定放大器
上傳時(shí)間： 2013-11-29
上傳用戶：黑漆漆
針對(duì)煤礦井下調(diào)度及緊急救援系統(tǒng)的需求，以DTMF編解碼模塊為核心，設(shè)計(jì)了具有自動(dòng)撥號(hào)功能的新型電話系統(tǒng)。該系統(tǒng)利用MT8880對(duì)DTMF信號(hào)的編解碼功能實(shí)現(xiàn)一鍵撥號(hào)和遠(yuǎn)程設(shè)置，通過(guò)檢測(cè)振鈴和忙音信號(hào)，完成自動(dòng)摘機(jī)和掛機(jī)過(guò)程，配合AGC等外圍電路達(dá)到話音清晰流暢的效果。 Abstract: To meet the demand for mine scheduling and emergency rescue system， with using DTMF signal codec as the core， a new telephone system was designed with automatic dialing function. In the system， the DTMF signal encoding and decoding function of MT8880 was used to achieve one-touch dialing and remote setting. The circuit detects the ringing and busy signal， and THEN completes automatic off-hook and hangup. With AGC(Automatic Gain Control) and other peripheral circuits， the voice was regulated to a clear and smooth effect.
標(biāo)簽： 8880 MT 撥號(hào)電話 系統(tǒng)設(shè)計(jì)
上傳時(shí)間： 2014-11-18
上傳用戶：ly1994
為了使音頻信號(hào)分析儀小巧可靠，成本低廉，設(shè)計(jì)了以2片MSP430F1611單片機(jī)為核心的系統(tǒng)。該系統(tǒng)將音頻信號(hào)送入八階巴特沃茲低通濾波器，對(duì)信號(hào)進(jìn)行限幅放大、衰減、電平位移、緩沖，并利用一單片機(jī)負(fù)責(zé)對(duì)前級(jí)處理后的模擬信號(hào)進(jìn)行采樣，將采集得到的音頻信號(hào)進(jìn)行4 096點(diǎn)基2的FFT計(jì)算，并對(duì)信號(hào)加窗函數(shù)提高分辨率，另一單片機(jī)負(fù)責(zé)對(duì)信號(hào)的分析及控制顯示設(shè)備。此設(shè)計(jì)精確的測(cè)量了音頻信號(hào)的功率譜、周期性、失真度指標(biāo)，達(dá)到較高的頻率分辨率，并能將測(cè)量結(jié)果通過(guò)紅外遙控器顯示在液晶屏上。 Abstract: o make the audio signal analyzer cheaper， smaller and more reliable， this system sends the audio signal to the eight-order butterworth filter， and THEN amplifies， attenuates， buffers it in a limiting range， transfers the voltage level of the signal before utilizing two MSP430F1611 MCU to realize the audio analysis. One is charged for sampling and dealing with the processed audio signal collected by the 4096 point radix-2 FFT calculation and imposes the window function to improve the frequency resolution. The other one controls the display and realizes the spectrum， periodicity， power distortion analysis in high resolution which is displayed in the LCD screen through the infrared remote control.
上傳時(shí)間： 2013-12-11
上傳用戶：jasonheung
介紹一種基于CAN總線的牽引變電站自動(dòng)化系統(tǒng)通訊規(guī)約的設(shè)計(jì)，CAN通訊規(guī)約采用標(biāo)準(zhǔn)幀，報(bào)文采用主動(dòng)發(fā)送和發(fā)送查詢兩種處理形式。該設(shè)計(jì)在城市輕軌與地鐵牽引變電站中的應(yīng)用表明：可實(shí)現(xiàn)間隔層和通訊處理層的數(shù)據(jù)快速、可靠的交換，提高牽引變電站的安全性和穩(wěn)定性 。 Abstract: This paper firstly presents a kind of design dealing with communicational protocol to the traction substation automation system based on CAN bus,and THEN comes up with the ideas that all frames of CAN communicational protocol should adopt the standard frame,and that messages be processed by two ways:sending initiatively and sending quiries.Subway and light rail application shows that the use of the CAN bus is possible to exchange data quickly and reliably between the layers of the middle and the communicational processing,hence to improve the safety and stability of traction substations.
上傳時(shí)間： 2013-11-07
上傳用戶：bs2005
介紹一種簡(jiǎn)單射頻識(shí)別系統(tǒng)設(shè)計(jì)。該設(shè)計(jì)包括閱讀器、應(yīng)答器和線圈3部分。由單片機(jī)控制閱讀器向應(yīng)答器發(fā)射無(wú)線信號(hào)，并接收應(yīng)答器回送的信號(hào)，再通過(guò)分析回送信號(hào)識(shí)別物品。閱讀器和應(yīng)答器之間以半雙工通信方式通信。 Abstract: A simple design of radio frequency identification system is given in this paper.The design includes reader,responder and winding.Through MCU，signals are sent to responder from reader，THEN corresponding signals are sent back. According to the analysis of the signals sent back，the objects can be identified.Half-duplex communication is adopted? between? reader? and? responder.
標(biāo)簽： 51單片機(jī) 無(wú)線識(shí)別 裝置
上傳時(shí)間： 2013-10-11
上傳用戶：plsee
介紹一種采用單片機(jī)技術(shù)和基站器件EM4095的手持式低頻RFID讀卡器方案。首先對(duì)整個(gè)系統(tǒng)框架進(jìn)行說(shuō)明，然后介紹主要功能模塊的設(shè)計(jì)，給出了各模塊的原理圖。重點(diǎn)描述了基站器件EM4095的性能參數(shù)和功能原理，最后描述了該系統(tǒng)的主程序流程圖。 Abstract: In this paper,a handheld RFID reader based on MCU and EM4095 is introduced.At first，the configuration of this system is explained.THEN the design of main modules and schematic documents are particularly presented.The parameters and principle of the chip EM4095 are introduced in detail. At last，the main software flow is given
標(biāo)簽： 4095 RFID EM 單片機(jī)
上傳時(shí)間： 2013-10-18
上傳用戶：windypsm
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