What are the advantages of Analog PLL over Digital PLL

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elec-eng

Joined: 16 Nov 2006
Posts: 277
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01 Jul 2009 16:16 advantages of pll

Hi all

could you answer my question please

thanks

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saro_k_82

Joined: 17 May 2007
Posts: 266
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Location: India

01 Jul 2009 17:37 analog pll

The only advantage is low jitter.

LvW

Joined: 07 May 2008
Posts: 1466
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Location: Germany

02 Jul 2009 13:01 advantages digital pll

elec-eng wrote:

Hi all
could you answer my question please
thanks

Perhaps it makes sense first to clarify what you really mean as the phrase "digital PLL" is used in several ways. Some people mean only a digital PD/PFD and some other really mean "complete digital" (including filter and a number controlled oscillator)

rfsystem

Joined: 25 Feb 2002
Posts: 858
Helped: 96

04 Jul 2009 9:00 digital pll advantages

Within the context of actual developments

for instance the TI driven time versus voltage driven argument

http://www2.iccad.com/data2/iccad/iccad_05acceptedpapers.nsf/9cfb1ebaaf59043587256a6a00031f78/e25be1f58da7d131872570530070afb2/$FILE/2A_3slides.PDF

by this guy

http://www.faqs.org/patents/inv/236491

it is a path to preserve system performance in the presence of NONscaling

Analog does not profit in general from further scaling but price and SOC aspects contrain analog to search for alternatives.

Digital PLL is one!

But VCO is analog, beside digital driven. The missing part is the high resolution phase detector. Analog phase detectors could easy resolve 200fs-1ps of a 20ns reference clock. The effort to built an 200fs resolving, 20ns range TDC is higher than everything else.

So a litle digital here and there to avoid NONscaling analog issues!