本文選題：微弱信號(hào)檢測(cè) + 石英晶體諧振器�。� 參考：《陜西師范大學(xué)》2014年碩士論文

【摘要】：在很多應(yīng)用場(chǎng)合,需要對(duì)微弱信號(hào)進(jìn)行檢測(cè),微弱信號(hào)檢測(cè)對(duì)檢測(cè)系統(tǒng)的設(shè)計(jì)有著特殊的要求。隨著科技的進(jìn)步,微弱信號(hào)檢測(cè)系統(tǒng)也在不斷的改進(jìn)與發(fā)展,目前在檢測(cè)系統(tǒng)中被廣泛使用的設(shè)備為鎖定放大器。 在鎖定放大器中,輸入信號(hào)通過相敏檢測(cè)器將其頻譜遷移到直流,再經(jīng)過低通濾波器濾除噪聲后輸出,輸出信號(hào)是與輸入信號(hào)的幅度成正比的直流信號(hào)。本文參照鎖定放大器進(jìn)行微弱信號(hào)檢測(cè)的基本原理,提出了一種低成本,易于實(shí)現(xiàn)的微弱信號(hào)檢測(cè)系統(tǒng),該系統(tǒng)的實(shí)現(xiàn)方案是利用混頻器將輸入的微弱信號(hào)變頻至某個(gè)固定頻率,后級(jí)電路對(duì)此固定頻率的信號(hào)進(jìn)行選頻放大,克服了放大倍數(shù)過高時(shí),直流放大中失調(diào)電壓造成輸出漂移嚴(yán)重的缺點(diǎn)。在該設(shè)計(jì)方案中,需要一個(gè)窄帶帶通濾波器,普通的LC濾波器不能滿足此要求,有源帶通濾波器則因?yàn)榉�(wěn)定性的影響,也很難實(shí)現(xiàn)很高的頻率選擇性。石英晶體諧振器由于具有極高的Q值,能夠達(dá)到窄帶濾波的效果。用石英晶體諧振器構(gòu)建晶體濾波器的方法常見于射頻信號(hào)處理。本文提出的微弱信號(hào)檢測(cè)方案與射頻接收機(jī)中超外差接收的原理類似,不過本方案中的石英晶體濾波器由32.768KHz的低頻石英晶體諧振器和運(yùn)算放大器構(gòu)成,在低頻段實(shí)現(xiàn)了窄帶濾波。該系統(tǒng)具有帶寬窄、設(shè)計(jì)簡(jiǎn)單、成本低等優(yōu)點(diǎn)。 論文重點(diǎn)論述了如何利用石英晶體諧振器設(shè)計(jì)低頻窄帶濾波器,在此基礎(chǔ)上設(shè)計(jì)了基于石英晶體濾波器的微弱信號(hào)檢測(cè)系統(tǒng),該系統(tǒng)通過引入混頻器有效克服了石英晶體濾波器中心頻率固定的缺陷,并采用多級(jí)濾波器以提高系統(tǒng)的頻率選擇性。文中詳細(xì)分析了檢測(cè)系統(tǒng)設(shè)計(jì)方案以及具體電路實(shí)現(xiàn),并對(duì)設(shè)計(jì)的檢測(cè)系統(tǒng)進(jìn)行了全面測(cè)試。測(cè)試結(jié)果表明,系統(tǒng)具有極高的頻率選擇性,在10Hz～200KHz頻率范圍內(nèi),3dB絕對(duì)帶寬小于2Hz,能夠很好的檢測(cè)出0.5uV峰峰值的微弱信號(hào),同時(shí)在不同頻率下具有較好的一致性,因此能夠滿足大多數(shù)微弱信號(hào)檢測(cè)系統(tǒng)的應(yīng)用要求。
[Abstract]:In many applications, weak signals need to be detected, and weak signal detection has special requirements for the design of detection system. With the development of science and technology, weak signal detection system has been continuously improved and developed. At present, lock amplifier is widely used in the detection system. In the locked amplifier, the input signal migrates the frequency spectrum to DC through the phase sensitive detector, and then filters the noise through the low-pass filter. The output signal is a DC signal proportional to the amplitude of the input signal. According to the basic principle of lock-in amplifier for weak signal detection, a low cost and easy to implement weak signal detection system is proposed in this paper. The scheme of the system is to use mixer to convert the weak input signal to a fixed frequency. The latter circuit selects the frequency to amplify the signal of the fixed frequency, which overcomes the high amplification ratio. The offset voltage in DC amplifier causes the serious drawback of output drift. In this design, a narrow band pass filter is needed, but the ordinary LC filter can not meet this requirement, and the active band pass filter is difficult to achieve high frequency selectivity because of the influence of stability. Because of its high Q value, quartz crystal resonator can achieve the effect of narrow band filter. The method of using quartz crystal resonator to construct crystal filter is commonly used in RF signal processing. The weak signal detection scheme proposed in this paper is similar to the principle of superheterodyne reception in radio frequency receiver, but the quartz crystal filter in this scheme is composed of 32.768KHz low frequency quartz crystal resonator and operational amplifier. Narrow band filtering is realized in low frequency band. The system has the advantages of narrow width, simple design and low cost. This paper mainly discusses how to use quartz crystal resonator to design low frequency narrow band filter, and then designs a weak signal detection system based on quartz crystal filter. The system overcomes the defect of fixed central frequency of quartz crystal filter by introducing mixer, and adopts multistage filter to improve the frequency selectivity of the system. In this paper, the design scheme and the circuit implementation of the detection system are analyzed in detail, and the overall test of the designed detection system is carried out. The test results show that the system has very high frequency selectivity, and the absolute bandwidth of 3 dB is less than 2 Hz in the 10Hz~200KHz frequency range, which can detect the weak signal of the peak value of 0.5uV well, and has good consistency at different frequencies. Therefore, it can meet the application requirements of most weak signal detection systems.
【學(xué)位授予單位】：陜西師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TN713;TN911.23

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 姜卓嬌;于生寶;白毅;張賢濤;;基于取樣積分技術(shù)的數(shù)據(jù)采集系統(tǒng)[J];吉林大學(xué)學(xué)報(bào)(信息科學(xué)版);2007年03期

2 胡順華;;一種基于Chebyshev函數(shù)的新型帶通濾波器設(shè)計(jì)方法[J];電訊技術(shù);2010年07期

3 Joshua Israelsonn;;噪聲與低噪聲設(shè)計(jì)的探討(上篇)[J];電子設(shè)計(jì)技術(shù);2004年05期

4 Joshua Israelsohn;;噪聲與低噪聲設(shè)計(jì)的探討(下篇)[J];電子設(shè)計(jì)技術(shù);2004年06期

5 李月,楊寶俊,譚力,盧金,李世哲;微弱周期脈沖信號(hào)的取樣積分-混沌系統(tǒng)聯(lián)合檢測(cè)方法[J];電子與信息學(xué)報(bào);2003年12期

6 畢松保;;并聯(lián)晶體振蕩器的振蕩頻率[J];高等學(xué)校電工課程教學(xué)工作通訊;1983年Z1期

7 王巍;趙國(guó)杰;李強(qiáng);;一種新的自適應(yīng)降噪方法及其應(yīng)用研究[J];計(jì)算機(jī)工程與應(yīng)用;2007年26期

8 程鵬飛;黃庚華;舒嶸;;基于模擬自相關(guān)方法的微弱激光脈沖信號(hào)檢測(cè)[J];紅外與激光工程;2012年10期

9 趙文禮;夏煒;劉鵬;王林澤;;基于混沌理論的微弱信號(hào)放大原理與方法研究[J];物理學(xué)報(bào);2010年05期

10 李向陽;劉曉暉;鄒顯炳;;耦合諧振帶通濾波器帶外特征及應(yīng)用[J];現(xiàn)代電子技術(shù);2009年24期

，

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