發(fā)布時間：2018-01-15 11:48

  本文關(guān)鍵詞：具有平均電壓反饋的高精度振蕩器的設(shè)計　出處：《電子科技大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 高頻RC振蕩器 平均電壓反饋 比較器延遲

【摘要】：自晶體振蕩器發(fā)明以來,由于其擁有穩(wěn)定度高、頻率抖動小的優(yōu)點而廣泛應(yīng)用于各類精密儀器與系統(tǒng)中。而隨著晶體管的問世,與其加工工藝水平的不斷提高,各類系統(tǒng)已經(jīng)開始由分立器件向單片集成發(fā)展。將原來的片外振蕩器以片內(nèi)集成的形式實現(xiàn)能大幅減少成本,降低功耗。張弛振蕩器具有與標(biāo)準(zhǔn)CMOS工藝相兼容的優(yōu)勢,在片上系統(tǒng)、生物醫(yī)療傳感器、高速接口以及微型計算機(jī)等應(yīng)用領(lǐng)域大量采用。張弛振蕩器采用反復(fù)對電容充放電的形式形成振蕩方波輸出,當(dāng)電壓達(dá)到比較器翻轉(zhuǎn)點時改變充放電狀態(tài),但是,比較器延遲易受電源、溫度等影響,因此振蕩器頻率精度受限。尤其是高頻率振蕩器的設(shè)計中,比較器延遲的影響更加突出。本文采用了一種平均電壓反饋結(jié)構(gòu)穩(wěn)定比較器延遲。平均電壓反饋結(jié)構(gòu)通過在基準(zhǔn)電壓和比較器之間插入有源濾波器實現(xiàn),平均電壓反饋環(huán)路通過自動調(diào)節(jié)有源濾波器的輸出來使有源濾波器的兩輸入端直流電壓相等,最終實現(xiàn)穩(wěn)定的輸出頻率。當(dāng)比較器延遲增加時,有源濾波輸出增加,比較器延遲減小時,有源濾波輸出減小。得益于平均電壓反饋,本文采用的比較器結(jié)構(gòu)非常簡單,而在普通張弛比較器中,比較性能要求較高。使得最終的振蕩頻率只由無源器件電阻、電容和相對穩(wěn)定的比較器延遲確定。本文的振蕩器主要針對開關(guān)電源的應(yīng)用場合而設(shè)計,通過與開關(guān)電源中原有振蕩器相比較,在振蕩頻率,比較器延遲等性能指標(biāo)上有較大改善。最終實現(xiàn)10MHz量級的50%占空比方波輸出,通過分頻率模塊可實現(xiàn)2.5MHz的輸出,最終的占空比也可通過數(shù)字電路降低,以適應(yīng)現(xiàn)有開關(guān)電源應(yīng)用對振蕩器的需求。振蕩器輸出的溫度系數(shù)主要由電阻決定,在對電阻進(jìn)行溫度補償后,從30℃至120℃輸出頻率有0.3%的變化。電源電壓從2.7V至3.9V變化時,輸出頻率改變2%。本次設(shè)計基于0.13μm CMOS工藝實現(xiàn),輸出結(jié)果通過trimming在6MHz-10MHz內(nèi)可調(diào)。最終繪制了版圖,進(jìn)行了流片。
[Abstract]:Since the invention of crystal oscillator, it has been widely used in various precision instruments and systems because of its advantages of high stability and low frequency jitter. All kinds of systems have begun to develop from discrete devices to monolithic integration. It can greatly reduce the cost to realize the original Oscillators in the form of in-chip integration. Reduce power consumption. Relaxation oscillators have the advantage of compatibility with standard CMOS processes, on-chip systems, biomedical sensors. High speed interface and microcomputer are widely used. Zhang Chi oscillator uses the form of repeated charge and discharge of capacitance to form oscillatory square wave output, which changes the state of charge and discharge when the voltage reaches the switching point of comparator. However, the comparator delay is easily affected by the power supply, temperature and so on, so the oscillator frequency accuracy is limited, especially in the design of high-frequency oscillator. In this paper, an average voltage feedback structure is used to stabilize the comparator delay. The average voltage feedback structure is realized by inserting an active filter between the reference voltage and the comparator. The average voltage feedback loop automatically adjusts the output of the active power filter to make the DC voltage of the two inputs of the active filter equal and finally achieve a stable output frequency. When the comparator delay increases. The active filter output increases, the comparator delay decreases, the active filter output decreases. Thanks to the average voltage feedback, the comparator used in this paper is very simple, but in the ordinary Zhang Chi comparator. The final oscillation frequency is determined only by passive device resistor, capacitance and relatively stable comparator delay. The oscillator is designed for the application of switching power supply. By comparing with the original oscillator in the switching power supply, the performance indexes such as oscillation frequency and comparator delay are greatly improved. Finally, the output of 10 MHz 50% duty cycle analogy wave is realized. The output of 2.5MHz can be realized by frequency division module, and the final duty cycle can be reduced by digital circuit. The output temperature coefficient of the oscillator is mainly determined by the resistor, after the temperature compensation of the resistor is carried out. The output frequency varies from 30 鈩，

本文編號：1428204