Reference clock loss detection circuit and detection method

Abstract

The invention belongs to the field of integrated circuit design, and provides a reference clock loss detection circuit, which comprises an alternating current coupling capacitor, a frequency divider,a voltage, current and voltage converter, a comparator and an output buffer, wherein thealternating current coupling capacitorseparates a direct current signal of the reference clock, the frequency divider sorts the duty ratio of a reference clock and adjusts the signal amplitude of the reference clock, the signal after frequency division passes through the voltage-current converter, a hopping clock signal and a non-hopping logic low signal can be distinguished, the comparator and the output buffer output a reference clock state signal, and when the reference clock to be detected is normal, lost and other abnormities happen, a signal is outputted to represent the state of the reference clock so as to realize detection of the state of the reference clock.

Description

technical field [0001] The invention belongs to the technical field of integrated circuits, and in particular relates to a circuit for detecting the state of a reference clock. Background technique [0002] In a computer or communication system, the clock circuit is a very important part of the system. The loss or abnormality of the external clock of the chip will affect the normal operation of the chip, so it is necessary to design a special circuit for clock detection. [0003] The clock detection circuit can adopt the counter mode, such as in patent 1 (application number: 99127039.8, authorized announcement number: CN 1148874C, patent name: a kind of clock signal pulse loss detection circuit), using multiple flip-flops, multiple inverters , an AND gate, a built-in counter and a comparator, the circuit simultaneously receives the external detected clock signal a and the extra counting clock signal b, and the built-in counter also receives the enable signal from the outside...

AI Technical Summary

Problems solved by technology

[0007] Although the patent application 3 does not rely on an additional counting reference clock, there are many units in the circuit and the structure is very complicated, so it is not easy to integrate

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