| 摘要 |
The invention relates to a phase-locked loop circuit comprising a phase detector, loop filter and an oscillator. The loop filter is implemented digitally instead of by means of analog components, thus requiring a digital to analog converter between the loop filter and the oscillator. The chip area required for such a digital loop filter is substantially smaller than an analog equivalence and can be implemented on a single integrated circuit die together with an oscillator, phase detector and possible counters. There is thus no need for the use of external components, greatly simplifying the design and manufacture of the circuit, and having reduced assemblage costs. Further, by means of the digital filter the loop dynamics are also easily changed. The digital to analog converter of the invention can be implemented in various ways. The invention also relates to a method for controlling the oscillator of such phase-locked loop circuit.
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