Patent
A method and arrangement for frequency synthesis
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TLDR
In this article, the phase position of pulses formed in a phase-locked loop is compared with the phase positions of pulses derived from a reference signal, and the phase error signal is amplified with a factor N (28) before adding or subtracting the correction value.Abstract:
The present invention relates to frequency synthesis with a controlled oscillator (20) included in a phase locked loop, where the frequency of the oscillator output signal is divided (22) periodically by different integers, such that the frequency is, on average, divided by a value which is equal to an integer N plus or minus a numeric fraction whose absolute value is smaller than one. The phase position of pulses formed in this way is compared with the phase position of pulses which derive from a reference signal (10, 12), therewith forming a phase error signal. For the purpose of suppressing periodic variations of an oscillator control signal as a result of phase jitter, there is added or subtracted to the phase error signal, in a known manner, a correction value (24, 26) which is dependent on the aforementioned numeric fraction. In order to eliminate the need to multiply the correction value by a factor which is proportional to the inverted value of the integer N, the phase error signal is instead amplified with a factor N (28) prior to adding or subtracting the correction value. The loop bandwidth is also held constant in this way.read more
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References
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