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In this paper, an all-digital phase-locked loop (ADPLL) is presented, and it is implemented on a field-programmable gate array. All components like the phase detector (PD), oscillator, and loop filter are realized as digital discrete-time components fed from analog-to-digital converters. The phase detection is realized by generating first an analytic signal using a compact implementation of the Hilbert transform and then computing the instantaneous phase with the CORDIC algorithm. A phase-unwrap component was realized, which extends the linear range of the PD, so that the linear model is valid in the full frequency range. This property leads to a constant lock-in time for arbitrary frequency changes. An analytic solution for the lock-in frequency range and the stability range including processing delays is given. All relations to design an ADPLL of the presented structure are derived. A detailed example application of an ADPLL designed as an offset local oscillator is given.
Circuits and Systems I: Regular Papers, IEEE Transactions on (Volume:57 , Issue: 9 )
Date of Publication: Sept. 2010