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An example illustrating the inaccuracy of using traditional loop parameter equations in the presence of delays. Here, loop parameter values for Kp and K i are calculated from (2), regardless of the number of delays.
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Modern implementations of discrete-time phase-locked loops (DT-PLLs) often contain delayed feedback. The delays are usually a side effect to pipelining, filtering, or other inner-loop mechanisms. Each delay increases the order of the system by introducing an additional pole to the closed-loop transfer function and, in many cases, makes the traditio...
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... in [4]. Ignoring the delays often results in inaccurate prediction of transient behavior, especially at high ω n T values [7]. For example, using (2) to achieve a damping factor ζ = .707 and ω n T = .05 in the presence of 10 sample delays will yield loop parameters K p and K i that do not provide a response with the expected characteristics (See Fig. ...
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Citations
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