石英晶體諧振器電容

晶(jing)振(zhen)(zhen)(zhen)的負(fu)載(zai)電(dian)容(rong)(rong)(rong)(rong)有高、低(di)兩(liang)(liang)類(lei)之別。低(di)者一般僅(jin)為(wei)十(shi)(shi)幾至幾百PF，而(er)高者則為(wei)無窮(qiong)大，兩(liang)(liang)者相差懸殊，決不(bu)(bu)(bu)能混用，否則會使(shi)振(zhen)(zhen)(zhen)蕩頻率偏(pian)離。兩(liang)(liang)類(lei)不(bu)(bu)(bu)同負(fu)載(zai)電(dian)容(rong)(rong)(rong)(rong)的晶(jing)振(zhen)(zhen)(zhen)使(shi)用方式絕然不(bu)(bu)(bu)同。低(di)負(fu)載(zai)電(dian)容(rong)(rong)(rong)(rong)晶(jing)振(zhen)(zhen)(zhen)都串聯(lian)(lian)幾十(shi)(shi)pF容(rong)(rong)(rong)(rong)量的電(dian)容(rong)(rong)(rong)(rong)器(qi)；而(er)高負(fu)載(zai)電(dian)容(rong)(rong)(rong)(rong)晶(jing)振(zhen)(zhen)(zhen)不(bu)(bu)(bu)但不(bu)(bu)(bu)能串聯(lian)(lian)電(dian)容(rong)(rong)(rong)(rong)器(qi)，還須并聯(lian)(lian)數pF小(xiao)容(rong)(rong)(rong)(rong)量電(dian)容(rong)(rong)(rong)(rong)器(qi)(外電(dian)路的分布(bu)晶(jing)振(zhen)(zhen)(zhen)電(dian)容(rong)(rong)(rong)(rong)有時也能取(qu)代這個并聯(lian)(lian)小(xiao)電(dian)容(rong)(rong)(rong)(rong))

晶體諧振器的激勵電平(ping)

激(ji)(ji)(ji)勵(li)(li)電(dian)(dian)(dian)平(ping)(ping)。一(yi)(yi)般取70 -100uA 為佳(jia)，用激(ji)(ji)(ji)勵(li)(li)功(gong)率(lv)表(biao)示(shi)時，一(yi)(yi)般取1 -100uW 為佳(jia)。激(ji)(ji)(ji)勵(li)(li)電(dian)(dian)(dian)平(ping)(ping)的(de)(de)(de)(de)大(da)小(xiao)(xiao)直(zhi)接影(ying)響石英(ying)諧(xie)(xie)振(zhen)器(qi)(qi)的(de)(de)(de)(de)性(xing)能，所(suo)以電(dian)(dian)(dian)路設計者一(yi)(yi)定(ding)要(yao)嚴(yan)(yan)格(ge)控制石英(ying)諧(xie)(xie)振(zhen)器(qi)(qi)在規定(ding)的(de)(de)(de)(de)激(ji)(ji)(ji)勵(li)(li)電(dian)(dian)(dian)平(ping)(ping)下(xia)工(gong)作，以便充(chong)分發揮石英(ying)諧(xie)(xie)振(zhen)器(qi)(qi)的(de)(de)(de)(de)特點。一(yi)(yi)般來講(jiang)，激(ji)(ji)(ji)勵(li)(li)電(dian)(dian)(dian)平(ping)(ping)偏小(xiao)(xiao)對于(yu)長穩有利，激(ji)(ji)(ji)勵(li)(li)電(dian)(dian)(dian)平(ping)(ping)稍大(da)對于(yu)短穩有利。但(dan)是(shi)激(ji)(ji)(ji)勵(li)(li)電(dian)(dian)(dian)平(ping)(ping)太(tai)大(da)，石英(ying)片(pian)振(zhen)動(dong)強，貼(tie)片(pian)晶(jing)體諧(xie)(xie)振(zhen)器(qi)(qi)報價，振(zhen)動(dong)區域溫度升高，石英(ying)片(pian)內產生(sheng)溫度梯度，會使(shi)頻(pin)率(lv)穩定(ding)度降低(di);激(ji)(ji)(ji)勵(li)(li)電(dian)(dian)(dian)平(ping)(ping)過(guo)大(da)，由(you)于(yu)機(ji)械形變(bian)(bian)超過(guo)彈性(xing)限(xian)度而(er)引起長期的(de)(de)(de)(de)晶(jing)格(ge)位移，使(shi)頻(pin)率(lv)產生(sheng)長期性(xing)的(de)(de)(de)(de)變(bian)(bian)化，貼(tie)片(pian)晶(jing)體諧(xie)(xie)振(zhen)器(qi)(qi)廠家，甚至有時會把石英(ying)片(pian)振(zhen)壞;激(ji)(ji)(ji)勵(li)(li)電(dian)(dian)(dian)平(ping)(ping)過(guo)大(da)，會使(shi)等效電(dian)(dian)(dian)阻(zu)增(zeng)加，Q 值下(xia)降，電(dian)(dian)(dian)阻(zu)溫度特性(xing)和頻(pin)率(lv)溫度特性(xing)變(bian)(bian)得(de)不(bu)規則;激(ji)(ji)(ji)勵(li)(li)電(dian)(dian)(dian)平(ping)(ping)過(guo)大(da)，貼(tie)片(pian)晶(jing)體諧(xie)(xie)振(zhen)器(qi)(qi)現貨，容(rong)易激(ji)(ji)(ji)起寄生(sheng)振(zhen)動(dong)，同(tong)時還會使(shi)老化變(bian)(bian)大(da)。當然，激(ji)(ji)(ji)勵(li)(li)電(dian)(dian)(dian)平(ping)(ping)過(guo)低(di)也(ye)會使(shi)信噪比(bi)變(bian)(bian)小(xiao)(xiao)而(er)影(ying)響短期穩定(ding)度，激(ji)(ji)(ji)勵(li)(li)電(dian)(dian)(dian)平(ping)(ping)太(tai)低(di)，諧(xie)(xie)振(zhen)器(qi)(qi)不(bu)易起振(zhen)，影(ying)響工(gong)作的(de)(de)(de)(de)穩定(ding)和可靠(kao)性(xing)。所(suo)以諧(xie)(xie)振(zhen)器(qi)(qi)使(shi)用應(ying)根據不(bu)同(tong)的(de)(de)(de)(de)要(yao)求嚴(yan)(yan)格(ge)控制激(ji)(ji)(ji)勵(li)(li)電(dian)(dian)(dian)平(ping)(ping)，更不(bu)能為了增(zeng)大(da)輸出而(er)隨意提高激(ji)(ji)(ji)勵(li)(li)電(dian)(dian)(dian)平(ping)(ping)。

晶(jing)體諧振器(qi)的作用(yong)(yong)及應用(yong)(yong)行(xing)業？

諧(xie)(xie)振器就是指產(chan)(chan)生諧(xie)(xie)振頻率的(de)電(dian)子(zi)元件，常(chang)用的(de)分為(wei)石英(ying)晶體諧(xie)(xie)振器和(he)陶瓷諧(xie)(xie)振器.起(qi)產(chan)(chan)生頻率的(de)作用，具有穩(wen)定，抗干擾性能良好的(de)特(te)點，廣泛應用于(yu)各(ge)種電(dian)子(zi)產(chan)(chan)品中，貼(tie)片晶體諧(xie)(xie)振器，石英(ying)晶體諧(xie)(xie)振器的(de)頻率精度要(yao)高于(yu)陶瓷諧(xie)(xie)振器，但成本也比陶瓷諧(xie)(xie)振器高.

諧振器(qi)重(zhong)要起頻率控制的(de)作(zuo)用，所有電(dian)子產品(pin)涉及頻率的(de)發射和接收都需要諧振器(qi)。

目前諧振器的類型按照外形可以分為直插式和貼片(pian)式兩(liang)中。