基于multisim及鎖相環(huán)的2PSK2ASK2FSK的調(diào)制解調(diào)電路仿真

1、 LANZHOU UNIVERSITY OF TECHNOLOGY畢業(yè)設(shè)計(jì)題 目 基于Multisim的鎖相環(huán)解調(diào)系統(tǒng)仿真 學(xué)生姓名 學(xué) 號(hào) 專業(yè)班級(jí) 指導(dǎo)教師 學(xué) 院 計(jì)算機(jī)與通信學(xué)院 辯論日期 基于Multisim的鎖相環(huán)解調(diào)系統(tǒng)仿真PLL Demodulation System Simulation Based on Multisim摘 要實(shí)現(xiàn)調(diào)頻波解調(diào)的方法有很多而鎖相環(huán)鑒頻是利用現(xiàn)代鎖相環(huán)技術(shù)來(lái)實(shí)現(xiàn)鑒頻具有工作穩(wěn)定失真小信噪比高等優(yōu)點(diǎn)所以被廣泛用在通信電路系統(tǒng)中鎖相環(huán)鑒相檢測(cè)輸入信號(hào)和輸出信號(hào)的相位差并將檢測(cè)出的相位差信號(hào)轉(zhuǎn)換成電壓信號(hào)輸出該信號(hào)經(jīng)低通濾波器濾波后形成壓控振蕩器的控制

2、電壓對(duì)振蕩器輸出信號(hào)的頻率實(shí)施控制該文首先介紹了鎖相環(huán)技術(shù)開展的現(xiàn)狀方向以及背景并對(duì)PLL的原理進(jìn)行了闡述在以上的根底上分別設(shè)計(jì)了2ASK2PSK2FSK的調(diào)制解調(diào)電路其最后采用Multisim軟件進(jìn)行仿真2ASK2FSK2PSK在整個(gè)電路設(shè)計(jì)中力求要做到電路簡(jiǎn)單并完成任務(wù)書提到的要求Multisim鎖相環(huán)AbstrackThere are many ways to realize frequency wave demodulation and PLL frequency which has the advantages of stable operation small distortion

3、 high signal-to-noise ratio and so on is achieved by using modern PLL frequency technology so it is widely used in communication circuit system Phase-locked loop through the difference of the phase detection of input signal and the output signal phase and the detected phase difference signal into ou

4、tput voltage signal the signal through a low pass filter After the formation of the voltage control oscillator the output signal of the oscillator frequency controlThis paper first introduces the present situation development direction phase-locked loop technology as well as the background and the p

5、rinciple of PLL is discussed On the basis of the above the modulation and demodulation circuit of 2ASK 2PSK 2FSK which function is a digital baseband signal is modulated by an analog signal and output were designed and then useing the PLL demodulation finally using Multisim software simulation In th

6、e 2ASK 2FSK 2PSK demodulation the output of the low pass filter waveform distortion is relatively large but finally it can regenerate digital baseband pulse sampling decision circuit after shaping In the circuit design and strive to do a simple circuit and complete the task book mentioned requiremen

7、tsKeywords modulate modulation PLLultisim目 錄第1章 緒論111 研究背景112 研究現(xiàn)狀113 研究?jī)?nèi)容介紹2第2章 根本原理321 Multisim介紹322 鎖相環(huán)根本原理5221鎖相環(huán)的根本組成5222 鎖相環(huán)的工作原理5第3章 調(diào)制解調(diào)電路設(shè)計(jì)831 2FSK調(diào)制解調(diào)電路設(shè)計(jì)8311 2FSK調(diào)制電路設(shè)計(jì)原理8312 2FSK調(diào)制單元電路的設(shè)計(jì)9313 2FSK解調(diào)單元電路的設(shè)計(jì)13314 2FSK解調(diào)電路的整體設(shè)計(jì)1532 2PSK調(diào)制解調(diào)電路設(shè)計(jì)17321 2PSK調(diào)制解調(diào)電路設(shè)計(jì)原理17322 2PSK調(diào)制與解調(diào)電路的設(shè)計(jì)與仿真1833

8、 2ASK調(diào)制解調(diào)電路設(shè)計(jì)19331 2ASK調(diào)制解調(diào)電路設(shè)計(jì)原理19332 2ASK調(diào)制與解調(diào)電路的設(shè)計(jì)與仿真2034 解調(diào)結(jié)果分析22總結(jié)24參考文獻(xiàn)25附錄 外文翻譯 26致謝50第1章 緒論11 研究背景 實(shí)現(xiàn)調(diào)頻波解調(diào)的方法有很多而鎖相環(huán)鑒頻是利用現(xiàn)代鎖相環(huán)技術(shù)來(lái)實(shí)現(xiàn)鑒頻方法具有工作穩(wěn)定失真小信噪比高等優(yōu)點(diǎn)所以被廣泛用在通信電路系統(tǒng)中鎖相環(huán)路是一種反應(yīng)電路鎖相環(huán)的英文全稱是Phase-Locked Loop簡(jiǎn)稱PLL其作用是使得電路相位同步因鎖相環(huán)可以實(shí)現(xiàn)輸出信號(hào)頻率對(duì)輸入信號(hào)頻率的自動(dòng)跟蹤所以鎖相環(huán)通常用于閉環(huán)跟蹤電路鎖相環(huán)在工作的過(guò)程中當(dāng)輸出信號(hào)的頻率與輸入信號(hào)的頻率相等時(shí)輸出電

9、壓與輸入電壓保持固定的相位差值即輸出電壓與輸入電壓的相位被鎖住它還具有載波跟蹤特性作為一個(gè)窄帶跟蹤濾波器可提取淹沒在噪聲中的信號(hào)用高穩(wěn)定的參考振蕩器鎖定可提供高穩(wěn)定的頻率源可進(jìn)行高精度的香味與頻率測(cè)量等等如今鎖相環(huán)解調(diào)器在通信雷達(dá)測(cè)量和自動(dòng)化控制等領(lǐng)域應(yīng)用極為廣泛隨著電子技術(shù)的開展對(duì)鎖相環(huán)解調(diào)的研究和應(yīng)用得到了越來(lái)越多的關(guān)注現(xiàn)在通過(guò)分析與研究加深對(duì)鎖相環(huán)解調(diào)方式的理解并根據(jù)它的原理設(shè)計(jì)出2FSK2PSK2ASKSDH網(wǎng)絡(luò)中在汽車MP3無(wú)線發(fā)射器中測(cè)量汽車轉(zhuǎn)速都是十分典型的應(yīng)用調(diào)頻波的特點(diǎn)是頻率隨調(diào)制信號(hào)幅度的變化而變化壓控振蕩器的振蕩頻率取決于輸入電壓的幅度當(dāng)載波信號(hào)的頻率與鎖相環(huán)的固有振蕩頻

10、率0相等時(shí)壓控振蕩器輸出信號(hào)的頻率將保持0不變假設(shè)壓控振蕩器的輸入信號(hào)除了有鎖相環(huán)低通濾波器輸出的信號(hào)uc外還有調(diào)制信號(hào)ui那么壓控振蕩器輸出信號(hào)的頻率就是以0為中心隨調(diào)制信號(hào)幅度的變化而變化的調(diào)頻波信號(hào)當(dāng)然鎖相環(huán)的許多優(yōu)越性使得鎖相環(huán)解調(diào)技術(shù)在很多我們周圍都可以見到的物品中發(fā)揮著其巨大的成效如今鎖相環(huán)路理論與研究日臻完善應(yīng)用范圍普及整個(gè)電子技術(shù)領(lǐng)域隨著通信及電子系統(tǒng)的飛速開展促使集成鎖相環(huán)和數(shù)字鎖相環(huán)突飛猛進(jìn)現(xiàn)在品種齊全繁多提高系統(tǒng)的工作穩(wěn)定性和可靠性和小型化目前仍朝著集成化數(shù)字化多用化方向迅速開展13 研究?jī)?nèi)容介紹調(diào)制和解調(diào)電路是通信設(shè)備中重要組成局部用待傳輸?shù)牡皖l信號(hào)去控制高頻載波參數(shù)電

11、路稱為調(diào)制電路解調(diào)是調(diào)制的逆過(guò)程從高頻已調(diào)信號(hào)中復(fù)原出原調(diào)制信號(hào)稱為解調(diào)電路該文主要建立了2ASK2FSK2PSK解調(diào)鎖相環(huán)路的輸出信號(hào)頻率可以精確地跟蹤輸入?yún)⒖夹盘?hào)頻率的變化環(huán)路鎖定后輸入?yún)⒖夹盘?hào)和輸出參考信號(hào)之間的穩(wěn)態(tài)相位誤差可以通過(guò)增加環(huán)路增益被控制在所需數(shù)值范圍內(nèi)這種輸出信號(hào)頻率隨輸入?yún)⒖夹盘?hào)頻率變化的特性稱為鎖相環(huán)的跟蹤特性利用此特性可以做載波跟蹤型鎖相環(huán)及調(diào)制跟蹤型鎖相環(huán)為了實(shí)現(xiàn)信息的遠(yuǎn)距離傳輸收信端接收到信號(hào)后必須進(jìn)行解調(diào)才能恢復(fù)原信號(hào)所謂的解調(diào)就是用攜帶信息的輸出信號(hào)uo來(lái)復(fù)原載波信號(hào)ui的參數(shù)載波信號(hào)的參數(shù)有幅度頻率和位相所以解調(diào)有調(diào)幅AM調(diào)頻FM和調(diào)相PM三種調(diào)幅波的特點(diǎn)是

12、頻率與載波信號(hào)的頻率相等幅度隨輸入信號(hào)幅度的變化而變化調(diào)頻波的特點(diǎn)是幅度與載波信號(hào)的幅度相等頻率隨輸入信號(hào)幅度的變化而變化調(diào)相波的特點(diǎn)是幅度與載波信號(hào)的幅度相等相位隨輸入信號(hào)幅度的變化而變化中調(diào)制出2FSK2ASK2PSK調(diào)制時(shí)采用的是鎖相環(huán)解調(diào)出來(lái)最后用Multisim進(jìn)行仿真出效果2ASK2FSK2PSK第2章 根本原理21 Multisim介紹隨著電子技術(shù)和計(jì)算機(jī)技術(shù)的開展電子產(chǎn)品已與計(jì)算機(jī)緊密相連電子產(chǎn)品的智能化日益完善電路的集成度越來(lái)越高而產(chǎn)品的更新周期卻越來(lái)越短Multisim 10是加拿大 Interactive Image Technologies公司 2001 年推出的 Mu

13、ltisim 最新版本可以設(shè)計(jì)測(cè)試和演示各種電子電路包括電工電路模擬電路數(shù)字電路射頻電路及局部微機(jī)接口電路等可以對(duì)被仿真的電路中的元器件設(shè)置各種故障如開路短路和不同程度的漏電等從而觀察不同故障情況它有豐富的元件庫(kù)為用戶提供元器件模型的擴(kuò)充和技術(shù)虛擬測(cè)試儀器儀表種類齊全其操作方法與實(shí)際儀器十分相似具有較為詳細(xì)的電路分析功能可以完成電路的瞬態(tài)分析和穩(wěn)態(tài)分析時(shí)域和頻域分析器件的線性和非線性分析電路的噪聲分析和失真分析離散傅里葉分析電路零極點(diǎn)分析交直流靈敏度分析等 18 種電路分析方法提供了多種輸入輸出接口Multisim10可以與國(guó)內(nèi)外流行的印刷電路板設(shè)計(jì)自動(dòng)化軟件Protel及電路仿真軟件Pspi

14、ce之間的文件接口也能通過(guò)Windows 電路圖送往文字處理系統(tǒng)中進(jìn)行編輯排版同時(shí)還支持VHDL和Verilog HDL語(yǔ)言的電路仿真與設(shè)計(jì)Multisim 10 Multisim 10提供了18種儀表儀表工具欄通常位于電路窗口的右邊也可以用鼠標(biāo)將其拖至菜單的下方呈水平狀Multisim 10具有以下特點(diǎn) 1 Multisim 10是一個(gè)電路原理設(shè)計(jì)電路功能測(cè)試的虛擬仿真軟件其元器件庫(kù)提供數(shù)千種電路元器件供實(shí)驗(yàn)選用同時(shí)也可以新建或擴(kuò)充已有的元器件庫(kù)而且建庫(kù)所需的元器件參數(shù)可以從生產(chǎn)廠商的產(chǎn)品使用手冊(cè)中查到因此可以很方便地在工程設(shè)計(jì)中使用 2 Multisim 10 的虛擬測(cè)試儀器儀表種類齊全有

15、一般實(shí)驗(yàn)用的通用儀器如萬(wàn)用表信號(hào)發(fā)生器雙通道示波器直流電源還有一般實(shí)驗(yàn)室少有或沒有的儀器如波特圖示儀字信號(hào)發(fā)生器邏輯分析儀邏輯轉(zhuǎn)換器失真度測(cè)量?jī)x頻譜分析儀和網(wǎng)絡(luò)分析儀等 3 Multisim 10 具有較詳細(xì)的電路分析功能可以完成電路的瞬態(tài)和穩(wěn)態(tài)分析時(shí)域和頻域分析器件的線性和非線性分析電路的噪聲和失真分析離散傅里葉分析電路零極點(diǎn)分析交直流靈敏度分析等以幫助設(shè)計(jì)人員分析電路的性能 4 Multisim10可以設(shè)計(jì)測(cè)試和演示各種電子電路包括電工電路模擬電路數(shù)字電路射頻電路及局部微機(jī)接口電路等可以對(duì)被仿真的電路中的元器件設(shè)置各種故障如開路短路和不同程度的漏電等從而觀察不同故障情況下的電路工作狀況在進(jìn)

16、行仿真的過(guò)程中還可以存儲(chǔ)測(cè)試點(diǎn)的所有數(shù)據(jù)列出被仿真電路的所有元器件清單以及存儲(chǔ)測(cè)試儀器的工作狀態(tài)顯示波形和具體數(shù)據(jù)Multisim10是一個(gè)電路原理設(shè)計(jì)電路功能測(cè)試的虛擬仿真軟件它用軟件的方法模擬電子線路元器件和儀器儀表實(shí)現(xiàn)了軟件即元器件和軟件即儀器 Multisim10是一個(gè)電路原理設(shè)計(jì)電路功能測(cè)試的虛擬仿真軟件該軟件為電子工程師提供了一個(gè)電路設(shè)計(jì)與仿真平臺(tái)不僅與國(guó)際著名的模擬電路仿真軟件spice兼容而且具有較強(qiáng)的 VHDL和 Verilog設(shè)計(jì)與仿真功能它具有界面形象直觀易懂采用圖形方式創(chuàng)立電路的特點(diǎn)它豐富的元件庫(kù)中提供了超過(guò)16000個(gè)組件全部采用世紀(jì)模型確保了仿真結(jié)果的真實(shí)性和實(shí)用性

17、它采用開放式的庫(kù)管理模式能自動(dòng)地生成模擬和數(shù)字組件模型這對(duì)新器件的補(bǔ)充十分有利Multisim10的虛擬測(cè)試儀器種類齊全有一般實(shí)驗(yàn)用的通用儀器如萬(wàn)用表信號(hào)發(fā)生器雙通道示波器直流交流電源還有一般實(shí)驗(yàn)室少有或沒有的儀器如波特圖示儀字信號(hào)發(fā)生器邏輯分析儀邏輯轉(zhuǎn)換器失真度測(cè)試儀頻譜分析儀和網(wǎng)絡(luò)分析儀等Multisim10具有較為詳細(xì)的電路分析功能可以完成電路的瞬態(tài)和穩(wěn)態(tài)分析時(shí)域和頻域分析器件的線性和非線性分析電路的噪聲分析和失真分析離散傅里葉分析電路零極點(diǎn)分析交直流靈敏度分析等電路分析方法以幫助設(shè)計(jì)人員分析電路的性能Multisim10可以設(shè)計(jì)測(cè)試和演示各種電子電路包括電工電路模擬電路數(shù)字電路射頻電路

18、及微機(jī)接口電路等可以對(duì)被仿真的電路中的元器件設(shè)置各種故障如開路短路和不同程度的漏電等從而觀察不同故障情況下的電路工作狀況在進(jìn)行仿真的同時(shí)軟件還可以存儲(chǔ)測(cè)試點(diǎn)的所有數(shù)據(jù)列出被仿真電路的所有元器件清單以及存儲(chǔ)測(cè)試儀器的工作狀態(tài)顯示波形和具體數(shù)許多電子設(shè)備要正常工作通常需要外部的輸入信號(hào)與內(nèi)部的振蕩信號(hào)同步利用鎖相環(huán)路就可以實(shí)現(xiàn)這個(gè)目的鎖相環(huán)路是一種反應(yīng)控制電路簡(jiǎn)稱鎖相環(huán)PLL鎖相環(huán)的特點(diǎn)是利用外部輸入的參考信號(hào)控制環(huán)路內(nèi)部振蕩信號(hào)的頻率和相位因鎖相環(huán)可以實(shí)現(xiàn)輸出信號(hào)頻率對(duì)輸入信號(hào)頻率的自動(dòng)跟蹤所以鎖相環(huán)通常用于閉環(huán)跟蹤電路鎖相環(huán)在工作的過(guò)程中當(dāng)輸出信號(hào)的頻率與輸入信號(hào)的頻率相等時(shí)輸出電壓與輸入電壓

19、保持固定的相位差值即輸出電壓與輸入電壓的相位被鎖住這就是鎖相環(huán)名稱的由來(lái)鎖相環(huán)通常由鑒相器PD環(huán)路濾波器LF和壓控振蕩器VCO三局部組成鎖相環(huán)組成的原理框圖如下圖圖21 鎖相環(huán)根本組成鎖相環(huán)中的鑒相器又稱為相位比擬器它的作用是檢測(cè)輸入信號(hào)和輸出信號(hào)的相位差并將檢測(cè)出的相位差信號(hào)轉(zhuǎn)換成電壓信號(hào)輸出該信號(hào)經(jīng)低通濾波器濾波后形成壓控振蕩器的控制電壓對(duì)振蕩器輸出信號(hào)的頻率實(shí)施控制鎖相環(huán)的工作原理鎖相環(huán)中的鑒相器通常由模擬乘法器組成利用模擬乘法器組成的鑒相器電路如下圖圖22 乘法器鑒相器的工作原理是設(shè)外界輸入的信號(hào)電壓和壓控振蕩器輸出的信號(hào)電壓分別為 2-2式中的0為壓控振蕩器在輸入控制電壓為零或?yàn)橹绷?/p>

20、電壓時(shí)的振蕩角頻率稱為電路的固有振蕩角頻率那么模擬乘法器的輸出電壓uD為 2-4 用低通濾波器LF將上式中的和頻分量濾掉剩下的差頻分量作為壓控振蕩器的輸入控制電壓即為 2-6 2-7式中的i為輸入信號(hào)的瞬時(shí)振蕩角頻率和分別為輸入信號(hào)和輸出信號(hào)的瞬時(shí)位相根據(jù)相量的關(guān)系可得瞬時(shí)頻率和瞬時(shí)位相的關(guān)系為即 2-9那么瞬時(shí)相位差d為 2-11對(duì)兩邊求微分可得頻差的關(guān)系式為 2-12 上式等于零說(shuō)明鎖相環(huán)進(jìn)入相位鎖定的狀態(tài)此時(shí)輸出和輸入信號(hào)的頻率和相位保持恒定不變的狀態(tài)為恒定值當(dāng)上式不等于零時(shí)說(shuō)明鎖相環(huán)的相位還未鎖定輸入信號(hào)和輸出信號(hào)的頻率不等隨時(shí)間而變因壓控振蕩器的壓控特性如下圖該特性說(shuō)明壓控振蕩器的振

21、蕩頻率u以0為中心隨輸入信號(hào)電壓的變化而變化該特性的表達(dá)式為圖23 壓控特性上式說(shuō)明當(dāng)隨時(shí)間而變時(shí)壓控振蕩器的振蕩頻率u也隨時(shí)間而變鎖相環(huán)進(jìn)入頻率牽引自動(dòng)跟蹤捕捉輸入信號(hào)的頻率使鎖相環(huán)進(jìn)入鎖定的狀態(tài)并保持0 i的狀態(tài)不變第3章 調(diào)制解調(diào)電路設(shè)計(jì)31 2FSK調(diào)制解調(diào)電路設(shè)計(jì)311 2FSK調(diào)制電路設(shè)計(jì)原理2FSK即叫做二進(jìn)制移頻鍵控或二進(jìn)制頻移鍵控2FSK信號(hào)產(chǎn)生的方法一般有兩種一種叫直接調(diào)頻法另一種叫頻移鍵控法1模擬調(diào)頻法即直接利用一個(gè)矩形脈沖序列對(duì)一個(gè)載波進(jìn)行調(diào)頻而獲得如圖31所示圖31 模擬調(diào)頻法直接調(diào)頻法是頻移鍵控通信方式早期采用的實(shí)現(xiàn)方法其優(yōu)點(diǎn)是調(diào)制方便設(shè)備簡(jiǎn)單得出的是2FSK信號(hào)相

22、位連續(xù)2鍵控法即利用受矩形脈沖序列控制的開關(guān)電路對(duì)兩個(gè)不同的獨(dú)立頻率源進(jìn)行選通如圖32所示圖 32 鍵控法2FSK鍵控法的特點(diǎn)是轉(zhuǎn)換速度快波形好穩(wěn)定度高且易于實(shí)現(xiàn)故應(yīng)用廣泛但設(shè)備要復(fù)雜些得出的是2FSK信號(hào)相位不連續(xù)該文采用鍵控法產(chǎn)生2FSK信號(hào)即用一個(gè)受基帶脈沖控制的開關(guān)電路去選擇兩個(gè)獨(dú)立頻率源的振蕩作為輸出設(shè)計(jì)原理圖如圖33所示圖 33 2FSK調(diào)制原理圖312 2FSK調(diào)制單元電路的設(shè)計(jì)要將時(shí)鐘脈沖信號(hào)經(jīng)過(guò)2FSK調(diào)制成為2FSK信號(hào)我們采用一個(gè)受基帶脈沖控制的開關(guān)電路去選擇兩個(gè)獨(dú)立的頻率源作為輸出鍵控法產(chǎn)生的2FSK信號(hào)頻率穩(wěn)定度可以做得很高并且沒有過(guò)度頻率它的轉(zhuǎn)換速度快波形好1四雙向

23、模擬開關(guān)CD4066CD4066的引腳功能如圖34所示每個(gè)封裝內(nèi)部有4個(gè)獨(dú)立的模擬開關(guān)每個(gè)模擬開關(guān)有輸入輸出控制三個(gè)端子其中輸入端和輸出端可互換當(dāng)控制端加高電平時(shí)開關(guān)導(dǎo)通當(dāng)控制端加低電平時(shí)開關(guān)截止模擬開關(guān)導(dǎo)通時(shí)導(dǎo)通電阻為幾十歐姆模擬開關(guān)截止時(shí)呈現(xiàn)很高的阻抗可以看成為開路模擬開關(guān)可傳輸數(shù)字信號(hào)和模擬信號(hào)可傳輸?shù)哪M信號(hào)的上限頻率為40MHz各開關(guān)間的串?dāng)_很小典型值為50dB圖 34 四雙向模擬開關(guān)CD4066輸入的基帶信號(hào)由轉(zhuǎn)換開關(guān)分成兩路一路控制f1 32KHz的載頻另一路經(jīng)倒相去控制f2 16KHz的載頻當(dāng)基帶信號(hào)為1時(shí)模擬開關(guān)1翻開模擬開關(guān)2關(guān)閉此時(shí)輸出f1 32KHz當(dāng)基帶信號(hào)為0時(shí)模擬

24、開關(guān)2開通此時(shí)輸出f2 16KHz于是可在輸出端得到2FSK已調(diào)信號(hào)如圖35所示圖 35 模擬開關(guān)2變頻電路變頻電路是將輸入的二進(jìn)制數(shù)字基帶信號(hào)通過(guò)控制載頻轉(zhuǎn)換成已調(diào)信號(hào)即2FSK調(diào)制信號(hào)兩路載頻分別經(jīng)射隨LC選頻射隨再送至模擬開關(guān)其中LC選頻電路函數(shù) 選頻網(wǎng)絡(luò)如圖36所示圖36 變頻電路圖32FSK調(diào)制的整體電路圖的設(shè)計(jì)圖37 2FSK的Multisim調(diào)制仿真電路圖42FSK調(diào)制電路的仿真圖38 脈沖信號(hào)輸出波形圖39 變頻電路輸出波形圖310 2FSK的仿真效果圖313 2FSK解調(diào)單元電路的設(shè)計(jì)鎖相環(huán)通常由鑒相器PD環(huán)路濾波器LF和壓控振蕩器VCO三局部組成鎖相環(huán)原理框圖如下圖 圖 3

25、11 2FSK解調(diào)原理框圖 1鎖相環(huán)中的鑒相器通常由模擬乘法器組成利用模擬乘法器組成的鑒相器電路如圖312所示圖312 乘法器2低通濾波器如圖313所示用低通濾波器LF將和頻分量濾掉剩下的差頻分量作為壓控振蕩器的輸入控制電壓uCt圖313 環(huán)路濾波器 3壓控振蕩器的壓控特性如圖314所示該特性說(shuō)明壓控振蕩器的振蕩頻率u以0為中心隨輸入信號(hào)電壓uct的變化而變化該特性的表達(dá)式為 3-1圖314 壓控特性上式說(shuō)明當(dāng)uct隨時(shí)間而變時(shí)壓控振蕩器的振蕩頻率u也隨時(shí)間而變鎖相環(huán)進(jìn)入頻率牽引自動(dòng)跟蹤捕捉輸入信號(hào)的頻率使鎖相環(huán)進(jìn)入鎖定的狀態(tài)并保持0 i的狀態(tài)不變壓控振蕩器的電路圖如圖315所示圖315壓控振

26、蕩器4抽樣判決電路LM311工作原理LM311是當(dāng)2腳電壓高于3腳電壓時(shí)輸出高電平反之那么輸出低電平引腳功能如下1腳 GROUNDGND 接地2腳 INPUT 正向輸入端3腳 INPUT- 反相輸入端7腳 OUTPUT 輸出端5腳 BALANCE 平衡6腳 BALANCESTROBE 平衡選通8腳 V 電源4腳 V- 電源- 圖316 LM311引腳圖 圖317 抽樣判決電路圖314 2FSK解調(diào)電路的整體設(shè)計(jì)2FSK解調(diào)電路的設(shè)計(jì)是采用鎖相環(huán)進(jìn)行解調(diào)2FSK信號(hào)通過(guò)鎖相環(huán)最終解調(diào)出數(shù)字基帶信號(hào)2FSK基于Multisim仿真的解調(diào)電路的整體電路設(shè)計(jì)圖如圖318所示圖318 2FSK的Mult

27、isim的解調(diào)仿真電路圖319 2FSK的Multisim解調(diào)電路的仿真32 2PSK調(diào)制解調(diào)電路設(shè)計(jì)321 2PSK調(diào)制解調(diào)電路設(shè)計(jì)原理PSK分為二進(jìn)制相位鍵控2PSK和多進(jìn)制相位鍵控MPSK該文主要介紹2PSK的調(diào)制與解調(diào)在二進(jìn)制數(shù)字調(diào)制中當(dāng)正弦載波的相位隨二進(jìn)制數(shù)字基帶信號(hào)離散變化時(shí)那么產(chǎn)生二進(jìn)制移相鍵控 2PSK 信號(hào)通常用已調(diào)信號(hào)載波的 0和 180分別表示二進(jìn)制數(shù)字基帶信號(hào)的 1 和 0二進(jìn)制移相鍵控信號(hào)的調(diào)制原理圖如所示其中圖是采用模擬的方法產(chǎn)生2PSK信號(hào)圖是采用數(shù)字鍵控的方法產(chǎn)生2PSK信號(hào)2PSK時(shí)采用的是鍵控法圖 模擬調(diào)頻法圖2PSK信號(hào)的解調(diào)通常都是采用相干解調(diào) 解調(diào)器

28、原理圖如圖 2FSK解調(diào)原理相同圖2PSK解調(diào)原理框圖322 2PSK調(diào)制與解調(diào)電路的設(shè)計(jì)與仿真2PSK調(diào)制電路采用鍵控法調(diào)制而解調(diào)電路的設(shè)計(jì)是采用鎖相環(huán)進(jìn)行解調(diào)2PSK信號(hào)通過(guò)鎖相環(huán)最終解調(diào)出數(shù)字基帶信號(hào)2PSK基于multisim仿真的調(diào)制解調(diào)電路的整體電路設(shè)計(jì)圖如圖323所示圖2PSK調(diào)制解調(diào)電路圖2PSK調(diào)制仿真圖與解調(diào)后的仿真圖如圖324圖2PSK調(diào)制解調(diào)電路圖仿真結(jié)果33 2ASK調(diào)制解調(diào)電路設(shè)計(jì)331 2ASK調(diào)制解調(diào)電路設(shè)計(jì)原理在二進(jìn)制數(shù)字振幅調(diào)制中載波的幅度隨著調(diào)制信號(hào)的變化而變化實(shí)現(xiàn)這種調(diào)制的方式有兩種1相乘法通過(guò)相乘器直接將載波和數(shù)字信號(hào)相乘得到輸出信號(hào)這種直接利用二進(jìn)制

29、數(shù)字信號(hào)的振幅來(lái)調(diào)制正弦載波的方式稱為相乘法其電路如下圖在該電路中載波信號(hào)和二進(jìn)制數(shù)字信號(hào)同時(shí)輸入到相乘器中完成調(diào)制所示圖325模擬相乘法 圖326數(shù)字鍵控法2ASKOOK信號(hào)有兩種根本的解調(diào)方法非相干解調(diào)包絡(luò)檢波法和相干解調(diào)同步檢測(cè)法相應(yīng)的接收系統(tǒng)如圖327圖328所示圖327非相干解調(diào)方式圖328相干解調(diào)方式該文2ASK的調(diào)制方法采用的是模擬相乘法而調(diào)制那么采用的是相干解調(diào)該文的2ASK解調(diào)原理框圖329如下圖329 2ASK解調(diào)原理框圖332 2ASK調(diào)制與解調(diào)電路的設(shè)計(jì)與仿真2ASK調(diào)制電路采用鍵控法調(diào)制而解調(diào)電路的設(shè)計(jì)是采用鎖相環(huán)進(jìn)行解調(diào)2ASK信號(hào)通過(guò)鎖相環(huán)最終解調(diào)出數(shù)字基帶信號(hào)2

30、ASK基于Multisim仿真的調(diào)制解調(diào)電路的整體電路設(shè)計(jì)圖如圖330所示圖2ASK調(diào)制解調(diào)電路圖圖 2ASK調(diào)制解調(diào)仿真圖34 解調(diào)結(jié)果分析由于在解調(diào)2ASK2FSK2PSK中C22FSK解調(diào)為例一開始我在C2設(shè)為10nF出來(lái)的波形如下列圖332 圖332 C2 10nF時(shí)的波形可見解調(diào)出來(lái)的基帶信號(hào)出現(xiàn)嚴(yán)重失真后經(jīng)過(guò)不斷的嘗試改變C2的值最終把C2的值設(shè)為100nF終于解調(diào)出很好的數(shù)字基帶信號(hào)如下列圖333圖333 C2 100nF時(shí)的波形總結(jié)該文分別設(shè)計(jì)了2ASK2PSK2FSK其最后采用Multisim軟件進(jìn)行仿真2ASK2FSK2PSKMultisim的鎖相解調(diào)系統(tǒng)設(shè)計(jì)的畢業(yè)設(shè)計(jì)任務(wù)

31、我首先查閱了大量的書本資料接著又上網(wǎng)搜集了許多有用信息有時(shí)候?yàn)榱苏业揭粋€(gè)適宜的電路而苦惱有時(shí)候又為取得一點(diǎn)成功而由衷的快樂(lè)當(dāng)最終的電路方案設(shè)計(jì)出來(lái)以后我請(qǐng)教了我的指導(dǎo)老師何老師及學(xué)的比擬好的同學(xué)他們的一個(gè)小小指點(diǎn)就給我們很大啟示和靈感對(duì)我的電路圖提出了很多有價(jià)值的建議在此對(duì)熱心幫助我的老師和同學(xué)表示衷心感謝在此次畢業(yè)設(shè)計(jì)中我充分體會(huì)到了熟練運(yùn)用相關(guān)軟件的重要性不像以前做的課程設(shè)計(jì)并沒有多少工作在計(jì)算機(jī)里實(shí)現(xiàn)的就僅僅畫出了電路圖之后用元器件在面包板上搭電路就行了本次畢業(yè)設(shè)計(jì)都高度依賴計(jì)算機(jī)從仿真到繪制原理圖再到參數(shù)調(diào)節(jié)可以說(shuō)每一步都很艱難每一步都是我一步一個(gè)腳印結(jié)結(jié)實(shí)實(shí)踩下去的通過(guò)畢業(yè)設(shè)計(jì)我增強(qiáng)

32、了對(duì)通信電子技術(shù)的理解學(xué)會(huì)查尋資料、比擬方案學(xué)會(huì)通信電路的設(shè)計(jì)、計(jì)算進(jìn)一步提高分析解決實(shí)際問(wèn)題的能力創(chuàng)造一個(gè)動(dòng)腦動(dòng)手、獨(dú)立開展電路實(shí)驗(yàn)的時(shí)機(jī)鍛煉分析、解決通信電子電路問(wèn)題的實(shí)際本領(lǐng)真正實(shí)現(xiàn)由課本知識(shí)向?qū)嶋H能力的轉(zhuǎn)化通過(guò)典型電路的設(shè)計(jì)與仿真加深對(duì)根本原理的了解增強(qiáng)了實(shí)踐能力參考文獻(xiàn)1出版社出版社 11 謝自美電子線路綜合設(shè)計(jì)華中科技大學(xué)出版社2006612 BestRoland EPhaseLooked Loop TheoryDesign and Applications McGRAWHill198413 沈偉慈通信電路西安電子科技大學(xué)出版社2004附錄 外文翻譯 Bridging the Ga

33、p between the Analog and Digital WorldsMost applications require the co-existence of analog and digital functionality and the benefits of combining this functionality on a single chip are significant Such mixed-signal integration however also presents significant challenges Furthermore digital and a

34、nalog developments tend to evolve at differing rates yet mixed-signal solutions for markets such as industrial automotive and medical must remain available over significant time periods The latest mixed-signal semiconductor processes are helping to address some of these issues and this article will

35、look at some of the issues designers should consider when specifying integrated mixed-signal solutionsMixed-signal solution for the real worldSystem designers often partition the digital portion from the analog section of a given design for a variety of reasons the availability of mixing components

36、for the two technologies the complexity of the digital design or again because of the existence of pure digital processing parts as standard products Placing the analog elements in an integrated circuit definitively allows the system designer to optimize the costs of its entire module This integrati

37、on approach is usually difficult for advanced markets such as telecommunications or computers but makes sense for more mature or conservative markets such as automotive medical and industrial For most of these mature markets applications digital functions are finding their way onto what once were pu

38、re analog designs Adding digital functions to an analog design is helped in part by the development of new process technologies that can handle both short-channel fast-switching digital transistors as well as high-voltage analog transistors For example AMI Semiconductors latest mixed-signal technolo

39、gy offers digital and analog integration capabilities on the same design platform The I3T technology family is based on standard CMOS 035m limiting the imum gate voltage to 33V Some consider this technology outdated from a pure digital designers point of view but it is at the forefront for the autom

40、otive industrial and medical marketsThis list of optional features that enables the design of real SoCs includes high voltage interfacing up to 80V microprocessing capabilities up to 32 bits wireless capabilities up to 28GHz and dense logic design up to 15K gatesmm2 Beside these capabilities NVM int

41、egration is possible E2PROM up to 4 Kbytes Flash memory up to half a megabit or On-Time-Programmable OTP cells for application calibrations The ability to integrate all these features on a chip gives the customer the possibility to be independent from the obsolescence of the stand-alone NVM market w

42、hich is more or less driven by the computer market This advantage is quite relevant when we consider the cost of re-qualifying a module for the OEMs in automotive for instance It also makes sense when considering the long lifespan of the applications embedded into cars the industrial environment or

43、medical self-treatment devices where patient cost is an important considerationNevertheless bridging the gap from digital to analog on a single chip does not occur without issues Clocking noise from high-speed digital circuits for instance often interferes with noise-sensitive analog functions In ad

44、dition switching currents from high-power analog functions can interfere with low-voltage digital processors The goal is to protect low-voltage transistors from the electric field effects of voltages that are 10 to 30 times higherThese important issues are not without solutions For example one of th

45、e latest releases in the I3T family the I3T50 DTI uses a deep trench isolation technique This technique uses a series of isolating trenches that bury deep into the IC substrate effectively creating on-chip pockets where noise and power supply parameters are carefully controlledOn top of its protecti

46、on skills the deep trench technology also helps to minimize die area by allowing dense packing of high-voltage analog pockets with low-voltage regions You can obtain improvements in die area of 10 to 60 percent over designs that use standard junction isolation techniquesAs mentioned earlier the reas

47、on that system designers are using deep sub-micron technologies in those markets is often linked to the availability of devices in those technologies not the complexity of the application itself The complexity can be handled in many cases by an 8-bit microcontroller or 32-bit for high-end applicatio

48、ns Products such as the 035m I3T are able to manage the integration at a reasonable cost A typical application diagram of a real mixed-signal SoC is shown in Figure 19Basically the chip integrates the system functionality from the sensor to the actuator going through some digital processing Conventi

49、onal mixed-signal technology allows analog control and signal processing functions such as amplifiers analog-to-digital converters ADCs and filters to be combined with digital functionality such as microcontrollers memory timers and logic control functions on a single customized chip All signals tha

50、t process an algorithm or arithmetic calculation are digital so conversion of analog to digital signals is mandatory when submitting data for comparison or processing by via a microcontroller while conversion from digital output signals to analog high-voltage signals is required to drive an actuator

51、 or a load The most recent mixed-signal technology AMIS developed significantly simplifies the implementation of such driver functionality by allowing much higher voltage functionality to be integrated into an IC alongside the relatively low voltages required for conventional mixed-signal functions

52、This high-voltage mixed-signal technology is particularly relevant to automotive electronics applications where higher voltage outputs to drive a motor or actuate a relay need to be combined with analog signal conditioning functions and complex digital processingA growing trend in mixed-signal circu

53、it design is to add some type of central processing circuit to the analog circuits For many applications the suitable choice of processing intelligence is an 8-bit microcontroller core such as an 8051 or 6502 8 bits remains the most popular choice as this type of SoC is not intended to replace compl

54、ex high-end central microcontrollers but more decentralized or slave applications such as sensor conditioning circuitry with local as close to the sensor as possible simple intelligence to control relays or motors An automotive example would be the lateral actuation of a cars headlamps when the stee

55、ring wheel is turned to improve the drivers safety and improve field of vision The sensor input would come from the steering angle via a serial link most of the time with a LIN or I2C protocol and the SoC would be close to the motor with an on-board set of algorithms to command the motors movementFo

56、r higher end applications that require more calculation power the move to ARM processors is possible This creates a high-end solution up to date for the mature markets which could last over the applications lifespan because the microcontroller would be a small part of an integrated circuit that emulates the modules functionalitiesIn order to understand how larger geometries can be better suited for some mixed-signal applications one needs to understand all of the characteristics involved Below we will discuss seven key characteristics however this