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Simply-realized crystal-oscillation-free circuit of USB (Universal Serial Bus) 1.1 device interface

A USB1.1, crystal oscillator technology, applied in the direction of electrical digital data processing, instruments, etc., can solve the problems of poor compatibility, increased test costs, etc., to achieve cost-saving, low-cost, high-performance effects

Active Publication Date: 2013-03-27
CHENGDU ANALOG CIRCUIT TECH INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The common defect of these schemes is: after the frequency calibration, as the external environment changes, the system clock will produce a non-negligible frequency offset, which will lead to poor compatibility of the USB1.1 device interface; at the same time, the necessary test steps It also increases the test cost, which is not conducive to the reduction of the overall cost

Method used

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  • Simply-realized crystal-oscillation-free circuit of USB (Universal Serial Bus) 1.1 device interface
  • Simply-realized crystal-oscillation-free circuit of USB (Universal Serial Bus) 1.1 device interface

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Embodiment Construction

[0015] The present invention will be further elaborated below in conjunction with the accompanying drawings and specific embodiments.

[0016] See figure 1 , The crystal oscillator-free simple implementation circuit in the present invention includes: high-frequency oscillator (1), sampling clock frequency divider (2), USB1.1 data receiver (3), USB1.1 data state machine (4), USB1 .1 Built-in clock decision device (5) and Delta_Sigma frequency divider (6).

[0017] The 1A output terminal of the high-frequency oscillator (1) is connected to the 2A input terminal of the sampling clock frequency divider (2); the 2B input terminal of the sampling clock frequency divider (2) is connected to the USB1.1 mode control signal SPEED, and the The 2C output of the sampling clock divider (2) is connected to the 4A input of the USB1.1 data state machine (4) and the 5A input of the USB1.1 built-in clock decision device (5); the USB1.1 data receiver (3) The 3A input terminal is connected to th...

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Abstract

The invention relates to a simply-realized crystal-oscillation-free circuit of a USB (Universal Serial Bus) 1.1 device interface. The simply-realized crystal-oscillation-free circuit comprises a high-frequency oscillator, a sampling clock frequency divider, a USB1.1 data receiver, a USB1.1 data state machine, a USB1.1 built-in clock judgment device and a Delta-Sigma frequency divider, wherein the high-frequency oscillator is used for providing a high-frequency clock, the USB1.1 data receiver is used for receiving effective information sent by a host, the USB1.1 data state machine is used for analyzing characteristic information, then a USB1.1 built-in clock judgment device takes the time span or the time interval of the characteristic information as a reference clock, and dynamically adjusts the frequency demultiplication number of the Delta-Sigma frequency divider through calculation, and finally, a high-precision built-in system clock is produced. When obtaining high performance, the simply-realized crystal-oscillation-free circuit realizes the crystal-oscillation-free technology of the USB 1.1 device interface, and meets the requirement on the low cost of the design of the USB1.1 interface to the maximum extent.

Description

technical field [0001] The invention relates to the application of the USB interface, in particular to a crystal oscillator-free realization circuit applied to the USB1.1 device interface. [0002] Background technique [0003] With the advancement of technology and technology, the fourth generation of USB series interface - USB3.0 technology is also becoming mature, but in many application fields, because the data transmission rate is not high, the USB1.1 interface is also required. The low-threshold trend of USB1.1 interface circuit design will inevitably bring about increasingly fierce price competition and performance competition, and its cost reduction has become an important part of the cost reduction of USB1.1-related products. [0004] In most applications of the USB1.1 device interface, a high-quality crystal oscillator is required as the input clock source to generate a high-precision system clock. The cost of high-quality crystal oscillator occupies a large prop...

Claims

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Application Information

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IPC IPC(8): G06F13/40
Inventor 不公告发明人
Owner CHENGDU ANALOG CIRCUIT TECH INC
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