Control method of low-gain voltage-controlled oscillator

Abstract

The invention discloses a phase-locked loop with a low-gain voltage-controlled oscillator. The phase-locked loop comprises a phase / frequency detector, a charge pump, a low-pass filter, an oscillator, a low-gain voltage-controlled circuit and a first frequency eliminator, wherein, the phase / frequency detector is used for generating a detection pulse according to a phase / frequency difference between a reference clock and a frequency-eliminated oscillation clock; the charge pump is used for generating detection voltages according to the detection pulse and further accumulating the detection voltages; the low-pass filter is used for generating an oscillator control voltage according to the detection voltages; the oscillator is used for generating an oscillation clock according to the oscillator control voltage; the low-gain voltage-controlled circuit is used for adjusting the oscillation clock of the oscillator according to a voltage boundary, temporarily determining the oscillation clock by using a first group of voltage boundaries and adjusting the oscillation clock to a relatively stable scope by using a second group of voltage boundaries within a relatively small scope; and the first frequency eliminator is used for eliminating the frequency of the oscillation clock of the oscillator, so as to generate the frequency-eliminated oscillation clock and transmit to the phase / frequency detector.

Description

technical field [0001] The invention relates to a phase-locked loop and its control method, in particular to a control method of a low-gain voltage-controlled oscillator. Background technique [0002] Please refer to Figure 1A , Figure 1A It is a schematic diagram illustrating the process of a low-gain voltage-controlled oscillator from power-on to clock locking in the prior art. Such as Figure 1A As shown, when the oscillator control bit Bit_vco is zero, the oscillator control voltage VCTR slowly rises from the position of circle 0 to the position of circle 1 which is greater than the upper limit VH of the voltage boundary. Therefore, the oscillator control bit Bit_vco jumps to one, and then the oscillator control voltage VCTR slowly rises from the position of circle 2 to the position of circle 3 which is greater than the upper limit VH of the voltage boundary. Until the oscillator control bit Bit_vco is equal to 2, the oscillator control voltage VCTR rises to the posit...

AI Technical Summary

Problems solved by technology

But when the phase-locked loop is stable, when the control bit Bit_vco of the oscillator corresponding to the oscillation clock of the oscillator changes suddenly, the phase-locked loop needs to be re-locked, and the system will not work normally

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