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锁相环的相位噪声对电子设备和电子系统的性能影响很大。从频域看它分布在载波信号两旁按幂律谱分布,无论做发射激励信号,还是接收机本振信号以及各种频率基准时,这些相位噪声将在解调过程中都会和信号一样出现在解调终端,引起基带信噪比下降,误码率增加。
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<P> 频率源可以说是一个通信系统的心脏,心脏的好坏很大程度上决定着一个机体的健康状况,而锁相环又是频率源的主要组成部分,因此性能优异的锁相环芯片对于通信系统来说是非常重要的。 </P> <P> 锁相环的相位噪声对电子设备和电子系统的性能影响很大。从频域看它分布在载波信号两旁按幂律谱分布,无论做发射激励信号,还是接收机本振信号以及各种频率基准时,这些相位噪声将在解调过程中都会和信号一样出现在解调终端,引起基带信噪比下降,误码率增加。 </P> <P> 低相噪Hittite锁相环产品分为集成VCO和没有集成VCO两种。集成VCO的PLL芯片包括了HMC820,HMC821,HMC826等。下面是与市场上同类产品的对比,以工作频段1720~2080MHz为例: </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: '宋体'"><?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: '宋体'; mso-spacerun: 'yes'">A<FONT face=宋体>公司</FONT></SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">B<FONT face=宋体>公司</FONT></SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">HMC821</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">在<FONT face="Times New Roman">1kHz</FONT><FONT face=宋体>频偏处相噪</FONT></SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">-85 dBc/Hz</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">-88 dBc/Hz</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">-107dBc/Hz</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">在<FONT face="Times New Roman">10kHz</FONT><FONT face=宋体>频偏处相噪</FONT></SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">-89 dBc/Hz</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">-96 dBc/Hz</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">-112 dBc/Hz</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">输出功率</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">3dBm</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">2dBm</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">10dBm</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><o:p></o:p></SPAN></P></TD></TR></TBODY></TABLE><!--EndFragment--></P> <P> HMC820,HMC821在芯片内部的频率输出端集成了放大器,因此其输出功率高于同类产品,在某些情况下,可以直接做为LO输出推动混频器,省掉一个本振口缓冲放大器,为设计者节省了空间和bom成本。 </P> <P> HMC820,HMC821是多频段产品,可工作在三个频段,如HMC821的工作频段包括了860~1040MHz,1720~2080MHz,及3440~4160MHz。以 1800MHZ, 900MHZ GSM 直放站为例,由于HMC821采用了内部集成分频器的方式,只用一颗HMC821芯片,使用同样的环路滤波器电路,就能满足900和1800MHz两个频段要求,这大大加快了设计进程。 </P> <P> Hittite公司内部集成VCO锁相环芯片采用独特的开关设计,如下图所示 </P> <P align=center><IMG src="/uploadfile/newspic/2010/201005/20100506162652398.jpg" border=0></P> <P> 芯片自动根据需要选择合适的开关,这种设计使用较小的电压就可以驱动VCO工作。在设计环路滤波器时不必使用运放等有源电路,仅用无源<A href="http://www.cps800.com/news/21471.htm">滤波器</A>就可以实现。这使得外围电路较为简单,减轻了RF工程师的负担。</P> <P> 在微波频段Hittite公司集成VCO的PLL芯片有HMC764,HMC765,HMC783,HMC807,工作频段涵盖了7.3-13.4GHz。HMC764在10kHz频偏处的相位噪声约为-102dBc/Hz,在分数模式下,其RMS Jitter为196 fs 。{$page$} 如果客户对PLL性能有更高的要求,可以用没有集成VCO的PLL芯片搭配合适的外围电路来实现。没有集成VCO的PLL芯片包括了HMC440,HMC698,HMC699,HMC700,HMC701,HMC702。 </P> <P> 以HMC700为例,芯片内部由鉴相器,电荷泵,N,R分频器构成,独有支持串口读写功能。HMC700外围电路隔离度设计良好时杂散可以低至-100dBc,远高于市场同类产品-80dBc的水平。下表是一些其他性能的比较。</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: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">A<FONT face=宋体>公司产品</FONT></SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">B<FONT face=宋体>公司产品</FONT></SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">HMC700</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">最大工作频率</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">7.5GHz</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">6GHz</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">8GHz</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">在<FONT face="Times New Roman">6GHz</FONT><FONT face=宋体>处相噪</FONT></SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">-87</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">-88</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">-103</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">Figure of Merit</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">-210</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">-213</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">-221</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'; mso-spacerun: 'yes'">防滑设置</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'">有</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'">有</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><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: '宋体'">有</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: '宋体'"><o:p></o:p></SPAN></P></TD></TR></TBODY></TABLE><!--EndFragment--></P> <P> 如果设计者对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。该芯片是专为低相噪应用设计的,当参考频率是100MHz时,在10KHz频偏处,相噪低至-153dBc/Hz,测试结果如下图 </P> <P align=center><IMG src="/uploadfile/newspic/2010/201005/20100506163152457.jpg" border=0></P> <P> Hittite公司以创新的设计使得其PLL产品性能优异,在相位噪声,杂散方面有着卓越表现,其芯片的高集成度使得外围电路简单,设计方便。所以随着<A href="http://www.cps800.com/news/21272.htm">电子技术</A>的发展,对频率源的相位噪声性能要求越来越高,Hittite的低相位噪声PLL,在物理、天文、无线电通信、雷达、航空、航天以及精密计量、仪器、仪表等各种领域里都将大有用武之地。■</P>