System and method of rapid locking and bandwidth calibration of phase-locked loop

Abstract

The invention provides a system and method of rapid locking and bandwidth calibration of a phase-locked loop. The method comprises gain calibration of a voltage controlled oscillator, rapid locking of a loop and bandwidth calibration. The method comprises steps of firstly before the phase-locked loop is output, carrying out pre-calibration on gain of the voltage controlled oscillator, and storing calibration results in a register, thereby greatly reducing effects on gain of the voltage controlled oscillator caused by technique deviation and nonlinearity of devices; and during the working process of the voltage controlled oscillator, carrying out real-time compensation based on conditions of the gain along with change of the temperature, and finally obtaining the voltage controlled oscillator gain which tends to be constant. In this way, by adjusting the charge pump and the loop filter, locking speed of the loop is accelerated; the bandwidth will not be changed; and the loop is kept to be stable.

Description

technical field [0001] The invention relates to the field of integrated circuits, in particular to a system and method for fast locking and bandwidth calibration of a phase-locked loop. Background technique [0002] A phase-locked loop is an electronic control system in which the phases of a reference signal are generated in a fixed relationship. As an accurate frequency source for electronic systems and equipment, the phase-locked loop responds to the frequency and phase of the input signal, and automatically increases or decreases the frequency of the controlled oscillator until the phase of the phase-locked loop circuit and the reference signal match. Modern analog phase-locked loops typically include phase comparators, charge pumps, loop filters, voltage-controlled oscillators, and frequency dividers, such as figure 1 shown. Through loop feedback, after the frequency of the output signal of the voltage-controlled oscillator is reduced, it is compared with the phase of ...

AI Technical Summary

Problems solved by technology

[0005] In the actual process, there are some factors that have a great impact on the accuracy and reliability of the above method, such as process errors and system temperature changes, which will cause the capacitance value in the voltage-controlled oscillator to shift, and the voltage-controlled oscillator The gain of the VCO is also changed accordingly, causing the output frequency of the voltage controlled oscillator to fail to reach some specific values, increasing the risk of loop lock failure

For another example, when the frequency division ratio of the loop feedback changes greatly, the loop bandwidth will also change greatly, resulting in changes in the loop characteristics, which also increases the risk of loop lock failure.

[0006] In view of the above problems, some methods are generally used to reduce the deviation of the gain of the voltage controlled oscillator, such as linear compensation for the gain of the voltage controlled oscillator, but it cannot deal with the influence of the process deviation very well.

Images