Kart_Mann
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Posts: 3
Chennai, India
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Hi,
A binary phase detector is a highly non linear element. Normally in PLLs we can use the continuous time approximation to write down the transfer function for small phase errors. However for systems using a binary PD I am unable to justify the asssumption of linearity, even for small phase errors. Yet, the transfer function derived from this assumption of linearity is used for phase noise estimation in a number of tutorials that i have referred ( 1,2).
How is this valid?
Is this only because of the linearity of the BBPDs for small phase due to flip flop metastability etc. as described in by Ken and Behzad Razavi in their paper(3) or am I missing the plot somewhere.
1. R.C. Walker :: Clock and Data Recovery for serial digital communication 2. Dean Banerjee:: PLL performance simulation and design 3. Kenneth Kundert, Behzad Razavi :: Analysis and Modelling of Bang Bang CDR circuits.
Thanking in advance, Regards, Kartik
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