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Clock generation device

A technology for generating devices and clocks, which can be used in synchronization devices, pulse generation, signal generation/distribution, etc., and can solve problems such as difficulty, rising cost, and cumbersome design.

Inactive Publication Date: 2004-05-26
ROHM CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, the cost rises, and the space for installing the circuit of this buffer memory is also required
In addition, due to constraints such as the clock speed driving the buffer memory, it is very cumbersome and makes the design more difficult

Method used

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Embodiment Construction

[0030] The clock generation device of the present invention will be described with reference to the drawings and the following embodiments.

[0031] The clock generating device of the present invention employs a phase modulation method in which the phase of the reference clock is controlled according to setting conditions that can be changed every clock cycle as a means for spreading the generated clock spectrum. According to this control method , by spectrally diffusing the cycle variation of the generated clock, and limiting the phase difference between the reference clock and the modulated (spectrum diffused) clock generated as a result of the control within a prescribed range, the modulation (spectrum diffusion) In the clock, a certain degree of synchronization can be guaranteed.

[0032] figure 1 It is a block diagram of a spectrum diffusion modulation clock generation circuit as an example of a clock generation device equipped with the above-mentioned components of the...

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PUM

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Abstract

A phase of a reference clock generated by an oscillator 1 is controlled by a variable delay circuit 2. The variable delay circuit 2 changes setting of control voltage by every clock period by a delay setting circuit 11 and performs phase modulation of the reference clock. Spread spectrum is performed by setting for varying period of an output modulation clock. In addition, the delay setting circuit 11 guarantees constant synchronicity in a spread spectrum clock by detecting an output state (clock edge) of a delay element of the variable delay circuit 2, and by restricting phase difference between the reference clock and the modulation clock to a prescribed range (for example, a half of reference clock period).

Description

technical field [0001] The present invention relates to a clock generation device used as an operating clock for electronic devices, microprocessors, and the like. More specifically, it relates to a clock generation device that reduces interference radiation noise (EMI: ElectroMagnetic Interference) generated by a high-frequency operating clock by modulating the clock cycle (spreading the spectrum). Background technique [0002] Nowadays, many electronic devices use microprocessors, digital circuits, etc., and these circuits have clock generators inside, and the circuits are operated by the generated clocks. In recent years, as the speed of operation has increased, the frequency of the necessary operating clock has also increased, making the interference radiation noise (EMI) generated from high-speed microprocessors a problem that cannot be ignored. For these MEIs, there are also government agencies that have taken action to establish restrictions. For example, the FCC (F...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L7/02G06F1/08H03L7/081H03L7/089H04B1/707
CPCG06F1/08H03L7/0812H03L7/0891H03L7/0816H04L7/02
Inventor 村田信野间口叶子横井静香
Owner ROHM CO LTD