【正文】 并保持 ω 0=ω i的狀態(tài)不變。引腳功能如下。 2FSK 基于 Multisim仿真的解調(diào)電路的整體電路設(shè)計(jì)圖如圖 ： 16 圖 2FSK的 Multisim的解調(diào)仿真電路 圖 2FSK的 Multisim解調(diào)電路的仿真 17 2PSK 調(diào)制解調(diào)電路設(shè)計(jì) 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）。 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) ,則產(chǎn)生二進(jìn)制移相鍵控 (2PSK)信號(hào) 。 和 180176。 二進(jìn)制移相鍵控信號(hào)的調(diào)制原理圖如 下 所示 。 碼 型 變換乘 法 器()st2 ()p s ketc o s c t?雙 極 性不 歸 零 圖 模擬調(diào)頻法 2 ()p s ketc o sc t?0?0180移 相 ()st開 關(guān) 電 路 圖 鍵控法 2PSK 信號(hào)的解調(diào)通常都是采用相干解調(diào) , 該文的 解調(diào)器原理圖如圖 與2FSK 解調(diào)原理相同 。 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 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 。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。 乘 法 器()stc o s c t?2 ()a s ketc o s c t?()st開 關(guān) 電 路2()A S Ket 圖 模擬相乘法 圖 數(shù)字鍵控法 2ASK/OOK 信號(hào)有兩種基本的解調(diào)方法：非相干解調(diào)（包絡(luò)檢波法）和相干解調(diào) 20 （同步檢測(cè)法），相應(yīng)的接收系統(tǒng)如圖 、圖 。該文的2ASK 解調(diào)原理框圖 ： 壓 控 振 蕩 器抽 樣 判 決模 擬 乘 法 器 低 通 濾 波 器調(diào) 制 信 號(hào)基 帶 信 號(hào)定 時(shí) 脈 沖 圖 2ASK 解調(diào)原理框圖 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)通過鎖相環(huán)最終解調(diào)出數(shù)字基帶信號(hào)。鎖相環(huán)鑒頻電路環(huán)路輸入頻率跟隨輸出頻率變化，即跟蹤，實(shí)現(xiàn)環(huán)路鎖定 困難，會(huì)出現(xiàn)毛刺。 在解調(diào)設(shè)計(jì)選取參數(shù)時(shí)，發(fā)現(xiàn)低通濾波器 中 C2 的值最影響波形的輸出，以 2FSK解調(diào)為例，一開始我在 C2 設(shè)為 10nF，出來的波形如下圖 ： 圖 C2=10nF 時(shí)的波形 可見解調(diào)出來的基帶信號(hào)出現(xiàn)嚴(yán)重失真。在對(duì) 2ASK、 2FSK、 2PSK 解調(diào)時(shí)，低通濾波器輸出的波形失真比較大，不過最后經(jīng)過抽樣判決電路整形后可以再生數(shù)字基帶脈沖。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)合適的電路而苦惱，有時(shí)候又為取得一點(diǎn)成功而由衷的高興。 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。 通過 畢業(yè) 設(shè)計(jì)，我增強(qiáng)了對(duì)通信電子技術(shù)的理解 ，學(xué)會(huì)查尋資料﹑比較方案，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)的機(jī)會(huì)，鍛煉分析﹑解決通信電子電路問題的實(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；通過典型電路的設(shè)計(jì)與仿真加深對(duì)基本原理的了解，增強(qiáng)了實(shí)踐能力。m, limiting the maximum gate voltage to V. Some consider this technology outdated, from a pure digital designer’s point of view, but it is at the forefront for the automotive, industrial and medical markets. 27 This list of optional features that enables the design of real SoCs includes high voltage interfacing up to 80 V, microprocessing capabilities up to 32 bits, wireless capabilities up to GHz, and dense logic design up to 15 K gates/mm2. Beside these capabilities, NVM integration is possible: E2PROM up to 4 Kbytes, Flash memory up to half a megabit or OnTimeProgrammable (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 standalone NVM market, which is more or less driven by the puter market. This advantage is quite relevant when we consider the cost of requalifying 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 medical selftreatment devices where patient cost is an important consideration. Nevertheless bridging the gap from digital to analog on a single chip does not occur without issues. Clocking noise from highspeed digital circuits, for instance, often interferes with noisesensitive analog functions. In addition, switching currents from highpower analog functions can interfere with lowvoltage digital processors. The goal is to protect lowvoltage transistors from the electric field effects of voltages that are 10 to 30 times higher. These important issues are not without solutions. For example, one of the 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。m I3T are able to manage the integration at a reasonable cost. A typical application diagram of a real mixedsignal SoC is shown in Figure . 28 Basically, the chip integrates the system functionality from the sensor to the actuator, going through some digital processing. Conventional mixedsignal technology allows analog control and signal processing functions such as amplifiers, analogtodigital converters (ADCs) and filters to be bined with digital functionality such as microcontrollers, memory, timers and logic control functions on a single, customized chip. All signals that process an algorithm or arithmetic calculation are digital, so conversion of analog to digital signals is mandatory when submitting data for parison or processing by via a microcontroller, while conversion from digital output signals to analog highvoltage signals is required to drive an actuator or a load. The most recent mixedsignal 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 mixedsignal functions. This highvoltage mixedsignal technology is particularly relevant to automotive electronics applications where higher voltage outputs — to drive a motor or actuate a relay — need to be bined with analog signal conditioning functions and plex digital processing. A growing trend in mixedsignal circuit 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 8bit 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 plex highend 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 car’s headlamps when the steering wheel is turned to improve the driver’s safety and improve field of vision. The sensor input would e 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 onboard set of algorithms