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Design >> Mixed-Signal Design >> Hogge phase detector
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Message started by Visjnoe on Jan 5^th, 2007, 2:07am

Title: Hogge phase detector
Post by Visjnoe on Jan 5^th, 2007, 2:07am

Dear all,

I have some questions on the Hogge phase detector:

1. Is the requirement on the concurrent on-time of the UP/DOWN signals comparable to that of a standard three-state PFD (impact on reference spur, CP noise etc.)? I think the same ideas apply, independent of the type of PFD (strictly speaking of course, the Hogge phase detector is a PD and not a PFD)

2. Given the constraint the input frequency is very close to the VCO frequency (few ppm) can the Hogge PD be used in a PLL that in one mode has to generate a CLK signal from data (recover clock from data) and in another mode clean up an external CLK signal?
Thus, the input to the PLL can be data or a CLK signal (same frequency): can Hogge serve both purposes (given the constraint of small frequency offset) or do we need to implement to PFD's: one, classical three-state and one Hogge?

Kind Regards

Peter

Title: Re: Hogge phase detector
Post by mg777 on Jan 14^th, 2007, 1:21pm

AFAIK, the Hogge's main advantages are linear phase characteristic and insensitivity to transition density. In contrast the Alexander is non-linear. The original Hogge circuit was eventually improved upon so that phase centering w.r.t the data was maintained without pattern dependence as well.

BTW, an interesting paper I came across on the web was:
http://www.ssc.pe.titech.ac.jp/publications/2006/20060526_philipus_ppt.pdf

M.G.Rajan
www.eecalc.com

Title: Re: Hogge phase detector
Post by Visjnoe on Jan 14^th, 2007, 11:58pm

Dear,

thanks for the paper by Matsuzawa.

Do you know if the dead-zone of the Hogge PD is an issue for CDR/PLL design (if it has a dead-zone at all)?
Besides this, I would think that convential PFD/CP design is much alike Hogge PD/CP design, right?

Kind Regards

Peter

ps: I only have experience with the three-state PFD

Title: Re: Hogge phase detector
Post by mg777 on Jan 15^th, 2007, 12:06pm

Ah, now you've got me extending myself into deeper waters. I suspect the phase characteristic will affect the PLL capture, especially with noisy input. A PLL is a fairly benign beast under lock, but the process of capture can be bizarre because of non-linear effects. A little state machine is usually adequate to assist the process.

M.G.Rajan
www.eecalc.com