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FFFFFF;'>每個(ge)單(dan)片機(ji)(ji)系(xi)統都(dou)(dou)有晶(jing)體振(zhen)蕩(dang)(dang)器(qi)(qi)，低成本晶(jing)振(zhen)振(zhen)蕩(dang)(dang)器(qi)(qi)原廠，整個(ge)過程稱(cheng)為(wei)晶(jing)體振(zhen)蕩(dang)(dang)器(qi)(qi)。晶(jing)體振(zhen)蕩(dang)(dang)器(qi)(qi)在單(dan)片機(ji)(ji)系(xi)統中起著(zhu)非常重(zhong)要的(de)作用(yong)。它結合單(dan)片機(ji)(ji)內部(bu)的(de)電路，產生(sheng)單(dan)片機(ji)(ji)所需的(de)時鐘(zhong)頻率(lv)(lv)。單(dan)片機(ji)(ji)所有指令的(de)執(zhi)行(xing)都(dou)(dou)基于(yu)此。晶(jing)體振(zhen)蕩(dang)(dang)器(qi)(qi)提(ti)供的(de)時鐘(zhong)頻率(lv)(lv)基于(yu)此。速(su)率(lv)(lv)越高，微控制(zhi)器(qi)(qi)的(de)運行(xing)速(su)度就越快。

晶體振(zhen)蕩(dang)器有(you)哪(na)些應用？

晶(jing)體振蕩器廣泛用于系統頻率源、導航以(yi)及其它通訊(xun)領域(yu)的普通石英晶(jing)體振蕩器(PXO)，工作(zuo)頻率范圍在1MHz至150MHz之(zhi)間(jian)，晶(jing)振振蕩器原廠，頻率穩定度為(wei)±25ppm，工篩晶(jing)振振蕩器原廠，±50ppm和±100ppm，輸(shu)出(chu)上升和下降時間(jian)為(wei)5ns，老化率為(wei)±5ppm/年。

還有主要(yao)用(yong)于移(yi)動電話(hua)、筆(bi)記本(ben)電腦、PHS、GPS設(she)備和(he)(he)其它無線通(tong)信設(she)備的SMD晶(jing)體(ti)振(zhen)蕩(dang)器(PXO)和(he)(he)SMD壓控/溫(wen)補(bu)晶(jing)體(ti)振(zhen)蕩(dang)器(VCXO/TCXO/VCTCXO)，其PXO和(he)(he)VCXO型SMD晶(jing)振(zhen)輸出邏輯(ji)與HCMOS/TTL兼容，因(yin)而提高了(le)器件(jian)的適應性和(he)(he)設(she)計的靈活性。用(yong)于手機的SMD晶(jing)振(zhen)主要(yao)特點有高精(jing)度(du)、高穩(wen)定度(du)和(he)(he)小(xiao)尺寸，精(jing)度(du)高達±5ppm，同(tong)時采用(yong)的晶(jing)片(pian)色澤白皙同(tong)時具有低腐蝕性、不易起振(zhen)，質量很(hen)穩(wen)定，尺寸規格有7×5mm、6×3.5mm、5×3.2mm、4×2.5mm。

頻率(lv)標準、通訊(xun)、電子儀表、測試(shi)裝(zhuang)置、精(jing)密計(ji)量等領(ling)域的高精(jing)度(du)高穩(wen)定(ding)度(du)石英晶體振(zhen)蕩器，可根據長期頻率(lv)穩(wen)定(ding)度(du)不同(tong)分為TCXO、OCXO、VCXO、SPXO、LPXO(低噪聲(sheng)晶體振(zhen)蕩器)等類型。

晶體振蕩器的選用

晶(jing)(jing)(jing)體(ti)(ti)(ti)(ti)振(zhen)(zhen)蕩(dang)(dang)(dang)(dang)器(qi)(qi)被廣泛(fan)應(ying)用(yong)(yong)(yong)(yong)(yong)到(dao)軍、民用(yong)(yong)(yong)(yong)(yong)通(tong)(tong)信電(dian)(dian)臺，微波(bo)通(tong)(tong)信設(she)備(bei)，程控(kong)電(dian)(dian)話(hua)交換機(ji)，無線(xian)電(dian)(dian)綜合(he)測(ce)試儀，BP機(ji)、移(yi)動電(dian)(dian)話(hua)發射臺，頻(pin)(pin)率(lv)計數(shu)器(qi)(qi)、GPS、遙控(kong)移(yi)動設(she)備(bei)等。它有(you)多(duo)種封裝(zhuang)，特點是(shi)電(dian)(dian)氣性(xing)能(neng)規范多(duo)種多(duo)樣。它有(you)好(hao)幾(ji)種不(bu)同的(de)(de)(de)(de)(de)類型：電(dian)(dian)壓(ya)(ya)(ya)控(kong)制晶(jing)(jing)(jing)體(ti)(ti)(ti)(ti)振(zhen)(zhen)蕩(dang)(dang)(dang)(dang)器(qi)(qi)（VCXO）、溫(wen)(wen)度(du)(du)補(bu)償晶(jing)(jing)(jing)體(ti)(ti)(ti)(ti)振(zhen)(zhen)蕩(dang)(dang)(dang)(dang)器(qi)(qi)（TCXO）、恒溫(wen)(wen)晶(jing)(jing)(jing)體(ti)(ti)(ti)(ti)振(zhen)(zhen)蕩(dang)(dang)(dang)(dang)器(qi)(qi)（OCXO），以(yi)及(ji)數(shu)字補(bu)償晶(jing)(jing)(jing)體(ti)(ti)(ti)(ti)振(zhen)(zhen)蕩(dang)(dang)(dang)(dang)器(qi)(qi)（MCXO或(huo)DTCXO），每種類型都有(you)自己的(de)(de)(de)(de)(de)性(xing)能(neng)。如(ru)果需(xu)(xu)(xu)要(yao)(yao)使(shi)設(she)備(bei)即開(kai)即用(yong)(yong)(yong)(yong)(yong)，您就(jiu)(jiu)必須選用(yong)(yong)(yong)(yong)(yong)VCXO或(huo)溫(wen)(wen)補(bu)晶(jing)(jing)(jing)振(zhen)(zhen)，如(ru)果要(yao)(yao)求穩定(ding)(ding)(ding)度(du)(du)在(zai)(zai)0.5ppm以(yi)上(shang)，工(gong)業高(gao)可(ke)靠晶(jing)(jing)(jing)振(zhen)(zhen)振(zhen)(zhen)蕩(dang)(dang)(dang)(dang)器(qi)(qi)原廠，則(ze)需(xu)(xu)(xu)選擇(ze)數(shu)字溫(wen)(wen)補(bu)晶(jing)(jing)(jing)振(zhen)(zhen)（MCXO）。模擬(ni)溫(wen)(wen)補(bu)晶(jing)(jing)(jing)振(zhen)(zhen)適用(yong)(yong)(yong)(yong)(yong)于穩定(ding)(ding)(ding)度(du)(du)要(yao)(yao)求在(zai)(zai)5ppm～0.5ppm之(zhi)間的(de)(de)(de)(de)(de)需(xu)(xu)(xu)求。VCXO只適合(he)于穩定(ding)(ding)(ding)度(du)(du)要(yao)(yao)求在(zai)(zai)5ppm以(yi)下的(de)(de)(de)(de)(de)產(chan)品。在(zai)(zai)不(bu)需(xu)(xu)(xu)要(yao)(yao)即開(kai)即用(yong)(yong)(yong)(yong)(yong)的(de)(de)(de)(de)(de)環境下，如(ru)果需(xu)(xu)(xu)要(yao)(yao)信號(hao)穩定(ding)(ding)(ding)度(du)(du)超過0.1ppm的(de)(de)(de)(de)(de)，可(ke)選用(yong)(yong)(yong)(yong)(yong)OCXO。 晶(jing)(jing)(jing)體(ti)(ti)(ti)(ti)振(zhen)(zhen)蕩(dang)(dang)(dang)(dang)器(qi)(qi)的(de)(de)(de)(de)(de)主(zhu)要(yao)(yao)特性(xing)之(zhi)一(yi)(yi)是(shi)工(gong)作(zuo)溫(wen)(wen)度(du)(du)內的(de)(de)(de)(de)(de)穩定(ding)(ding)(ding)性(xing)，它是(shi)決(jue)定(ding)(ding)(ding)振(zhen)(zhen)蕩(dang)(dang)(dang)(dang)器(qi)(qi)價格(ge)的(de)(de)(de)(de)(de)重要(yao)(yao)因(yin)素(su)(su)。穩定(ding)(ding)(ding)性(xing)愈(yu)高(gao)或(huo)溫(wen)(wen)度(du)(du)范圍愈(yu)寬，器(qi)(qi)件的(de)(de)(de)(de)(de)價格(ge)亦愈(yu)高(gao)。工(gong)業級標(biao)(biao)準規定(ding)(ding)(ding)的(de)(de)(de)(de)(de)-40～+75℃這個范圍往往只是(shi)出于設(she)計者(zhe)們的(de)(de)(de)(de)(de)習(xi)慣，倘若-30～+70℃已經夠用(yong)(yong)(yong)(yong)(yong)，那么就(jiu)(jiu)不(bu)必去追求更寬的(de)(de)(de)(de)(de)溫(wen)(wen)度(du)(du)范圍。設(she)計工(gong)程師要(yao)(yao)慎(shen)密決(jue)定(ding)(ding)(ding)特定(ding)(ding)(ding)應(ying)用(yong)(yong)(yong)(yong)(yong)的(de)(de)(de)(de)(de)實際需(xu)(xu)(xu)要(yao)(yao)，然后規定(ding)(ding)(ding)振(zhen)(zhen)蕩(dang)(dang)(dang)(dang)器(qi)(qi)的(de)(de)(de)(de)(de)穩定(ding)(ding)(ding)度(du)(du)。指標(biao)(biao)過高(gao)意味著花錢愈(yu)多(duo)。晶(jing)(jing)(jing)體(ti)(ti)(ti)(ti)老(lao)化是(shi)造成(cheng)頻(pin)(pin)率(lv)變(bian)化的(de)(de)(de)(de)(de)又一(yi)(yi)重要(yao)(yao)因(yin)素(su)(su)。根據(ju)目(mu)標(biao)(biao)產(chan)品的(de)(de)(de)(de)(de)預期壽命不(bu)同，有(you)多(duo)種方法可(ke)以(yi)減(jian)弱(ruo)這種影響。晶(jing)(jing)(jing)體(ti)(ti)(ti)(ti)老(lao)化會(hui)使(shi)輸出頻(pin)(pin)率(lv)按照(zhao)對數(shu)曲線(xian)發生變(bian)化，也就(jiu)(jiu)是(shi)說在(zai)(zai)產(chan)品使(shi)用(yong)(yong)(yong)(yong)(yong)的(de)(de)(de)(de)(de)一(yi)(yi)年(nian)(nian)，這種現象才(cai)較(jiao)為顯(xian)著。例(li)如(ru)，使(shi)用(yong)(yong)(yong)(yong)(yong)10年(nian)(nian)以(yi)上(shang)的(de)(de)(de)(de)(de)晶(jing)(jing)(jing)體(ti)(ti)(ti)(ti)，其老(lao)化速(su)度(du)(du)大約(yue)是(shi)一(yi)(yi)年(nian)(nian)的(de)(de)(de)(de)(de)3倍(bei)。采(cai)(cai)用(yong)(yong)(yong)(yong)(yong)特殊的(de)(de)(de)(de)(de)晶(jing)(jing)(jing)體(ti)(ti)(ti)(ti)加工(gong)工(gong)藝可(ke)以(yi)改善這種情況，也可(ke)以(yi)采(cai)(cai)用(yong)(yong)(yong)(yong)(yong)調節的(de)(de)(de)(de)(de)辦(ban)法解(jie)決(jue)，比如(ru)，可(ke)以(yi)在(zai)(zai)控(kong)制引腳上(shang)施(shi)加電(dian)(dian)壓(ya)(ya)(ya)（即增加電(dian)(dian)壓(ya)(ya)(ya)控(kong)制功能(neng)）等。