Re: Re: [oc] PLL vs DLL

["robinluo" <robinluo@cytecht.com>]

Hi Richard Herveille,

	Hehe!You are right,which one is better based on his detail application.
Any thing,pls let me know.

======= 2003-02-26 21:10:00 in your mail£º=======

>> Estimado mayank,
>>
>> Con fecha miércoles, 26 de febrero de 2003, 8:06:29, escribió:
>>
>> mdb> or the full control on clock delays & clock phases,which
>> mdb> architecture is preferrable PLL or DLL.i know tht each one has its
>> mdb> advantages,but both altera & Xilinx claims tht their PLL(in
>> mdb> stratix) & DLL(in virtex or spartan-IIE) architecture has an edge
>> mdb> over other.getting large multiples of frequencies in PLL is also
>> mdb> an added advantage.where i can find the comparison between the
>> mdb> two.
>>
>>    I have no answer for your question, but i can tell you DLL are faster
>> and better than PLL, the only thing is that PLL have much more resolution
>> than DLL.
>
>So you have absolutely no underlying arguments, but you can tell us that DLLs 
>are better ??? Are you a Xilinx fan??
>
>As said before both have their advantages and disvantages. DLLs can be 
>generated using pure digital blocks, you need some analog stuff for PLLs 
>(e.g. VCO). Due to the analog nature, PLLs usually require separate power/gnd 
>pins that need some special attention. DLLs have some build in hysteresis, 
>because the delay is digital - fixed delay steps -, but cannot generate 
>arbitrary frequencies, nor can they lock on any arbitrary input signal.
>The DLLs fixed delay can cause the clock to jump, meaning the output clock 
>doesn't have a nice 50/50 duty cycle. For a PLL this translates into jitter, 
>I think I read something like plus/minus 500ps.
>
>OK now what is better, a PLL or a DLL? I guess the answer is, depends on the 
>application and/or your preference.
>
>If you want to compare Altera's PLL and Xilinx DLL, check their websites. They 
>both tell you why their choice is the better one. So you know the strengths 
>and the weaknesses of both.
>
>Richard
>
>
>>
>>    Cheers
>>
>>
>> mdb> --
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>
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>.

= = = = = = = = = = = = = = = = = = = =
			

Robin Luo
Cytech Technology Ltd(Beijing Office)
Tel:13911045792
    8610-82684280 Ext 205
Fax:8610-82684277
E-mail:robinluo@cytecht.com
Web:http://www.cytecht.com
       2003-02-27


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