Calibration method and calibration circuit of on-chip clock

Abstract

The embodiment of the invention relates to a calibration method and a calibration circuit for an on-chip clock. The calibration method comprises the following steps: determining an externally input reference clock square wave signal and a clock counting threshold value according to a target locking frequency of the on-chip clock; connecting the on-chip clock calibration circuit with an externallyinput reference clock square wave signal; enabling the on-chip clock calibration circuit to count the high level of the reference clock square wave signal and count the on-chip clock signal generatedby the internal oscillator; when the number of externally input reference clock square wave signals reaches the clock counting threshold value, stopping counting, and obtaining a counting value of a current on-chip clock signal; comparing the count value of the on-chip clock signal with the clock count threshold; and if the count value of the on-chip clock signal is greater than or less than the clock count threshold, adjusting the current of an internal oscillator to adjust a calibration control word of the internal oscillator so as to calibrate the on-chip clock.

Description

technical field [0001] The invention relates to the technical field of chip design, in particular to an on-chip clock calibration method and a calibration circuit. Background technique [0002] For digital circuit systems, a stable and accurate clock is crucial to the work of the circuit system. Almost all digital systems process signals step by step according to the clock, and all parts of the system are also synchronized according to the clock. The circuit that generates this clock signal is the clock circuit. [0003] The core of the clock circuit is a relatively stable clock oscillator (usually a crystal oscillator), the oscillator generates a sine wave, and the frequency is not necessarily the clock frequency of the circuit, so the sine wave must be frequency-divided and processed. Clock pulses are formed and then distributed where needed. Used when making various parts of the system work. [0004] Due to the error of the manufacturing process of the clock oscillator...

AI Technical Summary

Problems solved by technology

[0004] Due to the error of the manufacturing process of the clock oscillator, the chips (die) in different places of the same wafer (wafer) will produce different oscillation frequencies. Although the clock is usually calibrated before leaving the factory, it is inevitable that the clock will have deviation and inaccuracy. Therefore, it is necessary to calibrate the clock signal frequency of the clock oscillator during use

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