Clock switching structure having automatic resetting function

Abstract

The invention discloses a clock switching structure having an automatic resetting function. The clock switching structure comprises a pulse generating circuit M1, a clock switching circuit M2, and a resetting generating circuit M3. The pulse generating circuit M1 is used for monitoring changing of a clock selection signal CS, and comprises three D triggers triggered by a rising edge of a clock and an XNOR gate. The clock switching circuit M2 is used to switch an output clock between a clock source CLK1 and a clock source CLK2, which are different from each other, and comprises a D trigger D4 used for triggering a rising edge of an enabling end, two two-input AND gates, and a two-input OR gate. The resetting generating circuit M3 is used to generate and eliminate a resetting signal automatically, and comprises three D triggers triggered by a rising edge provided with an asynchronous clearing end and a phase inverter INV. The clock switching structure is advantageous in that only the clock selection signal is required to be provided, and when the clock selection signal is changed, the resetting signal is generated automatically, and the clock switching is carried out; after the switching is completed, the resetting signal is eliminated after a certain period, and a controlled circuit can work normally.

Description

technical field [0001] The invention relates to a clock switching structure, in particular to a clock switching structure with an automatic reset function. Background technique [0002] With the development of integrated circuit manufacturing technology, the integration of chips is getting higher and higher. In recent years, the system-on-chip SoC (System on Chip) has flourished, enabling more sub-circuits with different functions to be integrated on one chip. However, as the scale of SoC continues to increase, two or more clock sources with different frequencies are often required in the design [1] , to meet the clock frequency requirements of different sub-circuits. Some special sub-circuits need to switch between different clock domains according to the actual situation. Therefore, the clock switching structure plays a very important role in SoC design. [0003] Ordinary clock switching structure is implemented only by data selector, because the clock selection signal...

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Problems solved by technology

[0004] After patent retrieval, the Chinese patent CN101299601B has proposed a clock switching circuit with a reset function, but the implementation of this switching structure is relatively complicated, and the switching process is relatively cumbersome [3]

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