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路;中心頻率Abstract Square wave generator in the science and engineering experiment has wide application, and at the same time in the life of the digital equipment, home appliances, electronic toys, and many other areas also have demand. Square wave signal is a kind of application of the signal, it is widely in scientific research, engineering education and the use of the production practice and is very popular. It is usually used as standard signal, used in electronic circuit performance test or parameter measurement. In addition, in many tester are required in the standard square wave signal detection some physical quantities. Produced by square wave circuit can hysteresit parator and R C, basic circuit structure, by 555 the timer add some resistance, capacitance of a peripheral device. Filter circuit is also in electronic circuits also have larger applications, such as people tend to get a specific frequency of the signal, but the actual input contains various frequency signal, would then use with the corresponding filter circuit to filter the frequency of the signal don39。 Second order wireless gain bandpass filters circuit。本設(shè)計基于對濾波電路的基礎(chǔ)上對信號處理做了一個簡單大設(shè)計,可實現(xiàn)當(dāng)輸入一個方波時,輸出同頻率的正弦波,完成方波到正弦波的轉(zhuǎn)化,通過設(shè)計可以將所學(xué)的電子技術(shù)知識運用到實際上,加深對濾波電路、方波產(chǎn)生電路的理解,鍛煉自己的動手能力,培養(yǎng)團(tuán)隊合作精神。第2章 系統(tǒng)總體設(shè)計 方案的設(shè)計與選擇 (1) 方波產(chǎn)生電路 方案一:用MAX0832集成芯片產(chǎn)生所需的方波,可靠性好,穩(wěn)定性好,但經(jīng)濟(jì)很貴。 方案三:用遲滯比較器外接R、C積分回路構(gòu)成多諧振蕩電路,由于設(shè)計和原理比較簡單,雖然對于高頻來說方波的前后沿不是很陡峭,但可以用轉(zhuǎn)換速率比較高的集成電壓比較器來代替運放基本能達(dá)到要求。(2) 雙電源產(chǎn)生電路 經(jīng)過查資料,對于直流電源的設(shè)計我們就給出了一種方案:220v交流電經(jīng)過三端輸出的變壓器后先經(jīng)過橋式整流電路得到脈動直流,在經(jīng)過濾波電路得到波動較小的紋波,最后接7817912(輸出5V時則換成7807905)輸出正12V、5V,負(fù)12V、5V。 方案二:由一個二階的低通濾波電路和一個二階的高通濾波電路串聯(lián)構(gòu)成。 在此我們選用第三種方案來設(shè)計電路。為了能讓555定時器產(chǎn)生脈沖,就得在外部電路上加一個RC充放電回路。就可以實現(xiàn)所達(dá)到的效果。(2)a 方案三的電路圖 源圖像(b)b 設(shè)計說明 集成電壓比較器比集成運放放大器的開環(huán)增益低、失調(diào)電壓大、共模抑制比小,因而它的靈敏度往往不如用集成運放構(gòu)成的比較器高,但由于集成電壓比較器通常工作在兩種狀態(tài)(輸出為高電平或低電平),因此不需要頻率補償電容,也就不存在像集成運放那樣因頻率補償電容引起轉(zhuǎn)換速率受限。c 設(shè)計原理該電路實際上就是在遲滯比較器的基礎(chǔ)上加了一個積分回路,遲滯比較器自身的特點有兩個閾值電壓+FVz和FVz,再接通電源的瞬間,輸出電壓處于不定狀態(tài),假設(shè)輸出電壓偏于正向飽和,即Vo=+Vz時,加到電壓比較器同相端得電壓為+FVz,而加于反相端的電壓,由于電容上的電壓不能突變,只能由輸出電+FVz時,輸出電壓迅速翻轉(zhuǎn)到Vz,Vz又通過R3對C進(jìn)行反相充電,知道Vc略負(fù)于Vz值時,輸出狀態(tài)再次發(fā)生翻轉(zhuǎn)。d 參數(shù)設(shè)計設(shè)t=0時,Vc=Vz,則在時間內(nèi),電容C上的電壓將以指