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鎖相環(huán)的相位噪聲對(duì)電子設(shè)備和電子系統(tǒng)的性能影響很大。從頻域看它分布在載波信號(hào)兩旁按冪律譜分布,無(wú)論做發(fā)射激勵(lì)信號(hào),還是接收機(jī)本振信號(hào)以及各種頻率基準(zhǔn)時(shí),這些相位噪聲將在解調(diào)過(guò)程中都會(huì)和信號(hào)一樣出現(xiàn)在解調(diào)終端,引起基帶信噪比下降,誤碼率增加。
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<P> 頻率源可以說(shuō)是一個(gè)通信系統(tǒng)的心臟,心臟的好壞很大程度上決定著一個(gè)機(jī)體的健康狀況,而鎖相環(huán)又是頻率源的主要組成部分,因此性能優(yōu)異的鎖相環(huán)芯片對(duì)于通信系統(tǒng)來(lái)說(shuō)是非常重要的。 </P> <P> 鎖相環(huán)的相位噪聲對(duì)電子設(shè)備和電子系統(tǒng)的性能影響很大。從頻域看它分布在載波信號(hào)兩旁按冪律譜分布,無(wú)論做發(fā)射激勵(lì)信號(hào),還是接收機(jī)本振信號(hào)以及各種頻率基準(zhǔn)時(shí),這些相位噪聲將在解調(diào)過(guò)程中都會(huì)和信號(hào)一樣出現(xiàn)在解調(diào)終端,引起基帶信噪比下降,誤碼率增加。 </P> <P> 低相噪Hittite鎖相環(huán)產(chǎn)品分為集成VCO和沒(méi)有集成VCO兩種。集成VCO的PLL芯片包括了HMC820,HMC821,HMC826等。下面是與市場(chǎng)上同類產(chǎn)品的對(duì)比,以工作頻段1720~2080MHz為例: </P> <P> <TABLE style="PADDING-RIGHT: 5.4pt; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; PADDING-TOP: 0pt; BORDER-COLLAPSE: collapse; mso-table-layout-alt: fixed"> <TBODY> <TR> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: rgb(0,0,0) 0.5pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: rgb(0,0,0) 0.5pt solid; WIDTH: 149.4pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=199> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p></SPAN></P></TD> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: rgb(0,0,0) 0.5pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: medium none; WIDTH: 99pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=132> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">A<FONT face=宋體>公司</FONT></SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: rgb(0,0,0) 0.5pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: medium none; WIDTH: 90pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=120> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">B<FONT face=宋體>公司</FONT></SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: rgb(0,0,0) 0.5pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: medium none; WIDTH: 87.7pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=116> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">HMC821</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD></TR> <TR style="HEIGHT: 21.95pt"> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: rgb(0,0,0) 0.5pt solid; WIDTH: 149.4pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=199> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">在<FONT face="Times New Roman">1kHz</FONT><FONT face=宋體>頻偏處相噪</FONT></SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: medium none; WIDTH: 99pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=132> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">-85 dBc/Hz</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: medium none; WIDTH: 90pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=120> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">-88 dBc/Hz</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: medium none; WIDTH: 87.7pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=116> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">-107dBc/Hz</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD></TR> <TR> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: rgb(0,0,0) 0.5pt solid; WIDTH: 149.4pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=199> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">在<FONT face="Times New Roman">10kHz</FONT><FONT face=宋體>頻偏處相噪</FONT></SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: medium none; WIDTH: 99pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=132> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">-89 dBc/Hz</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: medium none; WIDTH: 90pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=120> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">-96 dBc/Hz</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: medium none; WIDTH: 87.7pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=116> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">-112 dBc/Hz</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD></TR> <TR> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: rgb(0,0,0) 0.5pt solid; WIDTH: 149.4pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=199> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">輸出功率</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: medium none; WIDTH: 99pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=132> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">3dBm</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: medium none; WIDTH: 90pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=120> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">2dBm</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: medium none; WIDTH: 87.7pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=116> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">10dBm</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD></TR></TBODY></TABLE><!--EndFragment--></P> <P> HMC820,HMC821在芯片內(nèi)部的頻率輸出端集成了放大器,因此其輸出功率高于同類產(chǎn)品,在某些情況下,可以直接做為L(zhǎng)O輸出推動(dòng)混頻器,省掉一個(gè)本振口緩沖放大器,為設(shè)計(jì)者節(jié)省了空間和bom成本。 </P> <P> HMC820,HMC821是多頻段產(chǎn)品,可工作在三個(gè)頻段,如HMC821的工作頻段包括了860~1040MHz,1720~2080MHz,及3440~4160MHz。以 1800MHZ, 900MHZ GSM 直放站為例,由于HMC821采用了內(nèi)部集成分頻器的方式,只用一顆HMC821芯片,使用同樣的環(huán)路濾波器電路,就能滿足900和1800MHz兩個(gè)頻段要求,這大大加快了設(shè)計(jì)進(jìn)程。 </P> <P> Hittite公司內(nèi)部集成VCO鎖相環(huán)芯片采用獨(dú)特的開關(guān)設(shè)計(jì),如下圖所示 </P> <P align=center><IMG src="/uploadfile/newspic/2010/201005/20100506162652398.jpg" border=0></P> <P> 芯片自動(dòng)根據(jù)需要選擇合適的開關(guān),這種設(shè)計(jì)使用較小的電壓就可以驅(qū)動(dòng)VCO工作。在設(shè)計(jì)環(huán)路濾波器時(shí)不必使用運(yùn)放等有源電路,僅用無(wú)源<A href="http://leisuda.cn/news/21471.htm">濾波器</A>就可以實(shí)現(xiàn)。這使得外圍電路較為簡(jiǎn)單,減輕了RF工程師的負(fù)擔(dān)。</P> <P> 在微波頻段Hittite公司集成VCO的PLL芯片有HMC764,HMC765,HMC783,HMC807,工作頻段涵蓋了7.3-13.4GHz。HMC764在10kHz頻偏處的相位噪聲約為-102dBc/Hz,在分?jǐn)?shù)模式下,其RMS Jitter為196 fs 。{$page$} 如果客戶對(duì)PLL性能有更高的要求,可以用沒(méi)有集成VCO的PLL芯片搭配合適的外圍電路來(lái)實(shí)現(xiàn)。沒(méi)有集成VCO的PLL芯片包括了HMC440,HMC698,HMC699,HMC700,HMC701,HMC702。 </P> <P> 以HMC700為例,芯片內(nèi)部由鑒相器,電荷泵,N,R分頻器構(gòu)成,獨(dú)有支持串口讀寫功能。HMC700外圍電路隔離度設(shè)計(jì)良好時(shí)雜散可以低至-100dBc,遠(yuǎn)高于市場(chǎng)同類產(chǎn)品-80dBc的水平。下表是一些其他性能的比較。</P> <P> <TABLE style="PADDING-RIGHT: 5.4pt; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; PADDING-TOP: 0pt; BORDER-COLLAPSE: collapse; mso-table-layout-alt: fixed"> <TBODY> <TR> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: rgb(0,0,0) 0.5pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: rgb(0,0,0) 0.5pt solid; WIDTH: 106.5pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=142> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: rgb(0,0,0) 0.5pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: medium none; WIDTH: 106.5pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=142> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">A<FONT face=宋體>公司產(chǎn)品</FONT></SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: rgb(0,0,0) 0.5pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: medium none; WIDTH: 106.55pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=142> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">B<FONT face=宋體>公司產(chǎn)品</FONT></SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: rgb(0,0,0) 0.5pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: medium none; WIDTH: 106.55pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=142> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">HMC700</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD></TR> <TR> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: rgb(0,0,0) 0.5pt solid; WIDTH: 106.5pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=142> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">最大工作頻率</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: medium none; WIDTH: 106.5pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=142> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">7.5GHz</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: medium none; WIDTH: 106.55pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=142> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">6GHz</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: medium none; WIDTH: 106.55pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=142> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">8GHz</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD></TR> <TR> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: rgb(0,0,0) 0.5pt solid; WIDTH: 106.5pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=142> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">在<FONT face="Times New Roman">6GHz</FONT><FONT face=宋體>處相噪</FONT></SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: medium none; WIDTH: 106.5pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=142> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">-87</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: medium none; WIDTH: 106.55pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=142> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">-88</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: medium none; WIDTH: 106.55pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=142> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">-103</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD></TR> <TR> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: rgb(0,0,0) 0.5pt solid; WIDTH: 106.5pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=142> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">Figure of Merit</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: medium none; WIDTH: 106.5pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=142> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">-210</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: medium none; WIDTH: 106.55pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=142> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">-213</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: medium none; WIDTH: 106.55pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=142> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">-221</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD></TR> <TR> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: rgb(0,0,0) 0.5pt solid; WIDTH: 106.5pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=142> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'; mso-spacerun: 'yes'">防滑設(shè)置</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: medium none; WIDTH: 106.5pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=142> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'">有</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: medium none; WIDTH: 106.55pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=142> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'">有</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD> <TD style="BORDER-RIGHT: rgb(0,0,0) 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0pt; BORDER-LEFT: medium none; WIDTH: 106.55pt; PADDING-TOP: 0pt; BORDER-BOTTOM: rgb(0,0,0) 0.5pt solid" vAlign=top width=142> <P class=p0 style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt; LINE-HEIGHT: 150%"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'">有</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋體'"><o:p></o:p></SPAN></P></TD></TR></TBODY></TABLE><!--EndFragment--></P> <P> 如果設(shè)計(jì)者對(duì)PLL芯片的相噪性能有近似苛刻的要求,相信Hittite公司的HMC440仍能助你一臂之力。該芯片是專為低相噪應(yīng)用設(shè)計(jì)的,當(dāng)參考頻率是100MHz時(shí),在10KHz頻偏處,相噪低至-153dBc/Hz,測(cè)試結(jié)果如下圖 </P> <P align=center><IMG src="/uploadfile/newspic/2010/201005/20100506163152457.jpg" border=0></P> <P> Hittite公司以創(chuàng)新的設(shè)計(jì)使得其PLL產(chǎn)品性能優(yōu)異,在相位噪聲,雜散方面有著卓越表現(xiàn),其芯片的高集成度使得外圍電路簡(jiǎn)單,設(shè)計(jì)方便。所以隨著<A href="http://leisuda.cn/news/21272.htm">電子技術(shù)</A>的發(fā)展,對(duì)頻率源的相位噪聲性能要求越來(lái)越高,Hittite的低相位噪聲PLL,在物理、天文、無(wú)線電通信、雷達(dá)、航空、航天以及精密計(jì)量、儀器、儀表等各種領(lǐng)域里都將大有用武之地!</P>