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https://designers-guide.org/forum/YaBB.pl Design >> Analog Design >> how to determine loop bandwidth for PI with digital filter? https://designers-guide.org/forum/YaBB.pl?num=1302621351 Message started by casual on Apr 12th, 2011, 8:15am |
Title: how to determine loop bandwidth for PI with digital filter? Post by casual on Apr 12th, 2011, 8:15am how to determine loop bandwidth for PI with digital filter? |
Title: Re: how to determine loop bandwidth for PI with digital filter? Post by raja.cedt on Apr 12th, 2011, 9:01am what do you mean by PI loop BW..its an open loop system |
Title: Re: how to determine loop bandwidth for PI with digital filter? Post by casual on Apr 12th, 2011, 5:12pm PI output go to a CDR loop |
Title: Re: how to determine loop bandwidth for PI with digital filter? Post by raja.cedt on Apr 12th, 2011, 9:35pm yes, so should ask CDR bandwidth riteee.... so this is a different question now. Tell me weather your CDR is 1st order or 2nd order from there we can decide. |
Title: Re: how to determine loop bandwidth for PI with digital filter? Post by casual on Apr 13th, 2011, 1:12am since PI replacing the vco, there is no 1/s integral part. Then it should be 1st order. digital loop filter is used. |
Title: Re: how to determine loop bandwidth for PI with digital filter? Post by raja.cedt on Apr 13th, 2011, 5:02am correct but what about loop filter. General rule is if you need only phase tracking use first order, but if any frequency tracking required (like systems which are having ppm between TX and RX) then 2nd order imp. Thanks. |
Title: Re: how to determine loop bandwidth for PI with digital filter? Post by casual on Apr 13th, 2011, 5:55am how to determine the loop filter? input does not have ssc. could you point me some of the good papers? |
Title: Re: how to determine loop bandwidth for PI with digital filter? Post by raja.cedt on Apr 14th, 2011, 10:12pm hi, http://www.ece.tamu.edu/~spalermo/ecen689/cdr_hlee_stanford_2006.pdf http://www.ece.tamu.edu/~spalermo/ecen689/dig_cdr_bb_pll_sonntag_jssc_2006.pdf Thanks. |
Title: Re: how to determine loop bandwidth for PI with digital filter? Post by casual on Apr 14th, 2011, 11:25pm thank you :) |
Title: Re: how to determine loop bandwidth for PI with digital filter? Post by casual on Apr 24th, 2011, 7:28am how could the PI has 2nd order loop?? 2nd order loop implies that the PI can adjust its clock frequency. The PI has only fixed frequency but the phase can be adjusted. |
Title: Re: how to determine loop bandwidth for PI with digital filter? Post by raja.cedt on Apr 24th, 2011, 12:36pm good question, i also understand little bit. So please refer the above thesis. What i feel is rate of change of phase is frequency. If you know any answer for this let me know Thanks. |
Title: Re: how to determine loop bandwidth for PI with digital filter? Post by casual on May 12th, 2011, 6:09am got it. freq=d(phi)/dt (1st order) ramping freq = d(phi)^2/dt^2 (2nd order) |
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