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Oscillation frequency control circuit

A technology for controlling circuits and oscillation frequency, which is applied in the field of oscillation frequency control circuits, can solve problems such as inability to operate, and achieve the effect of ensuring oscillation frequency

Active Publication Date: 2009-07-22
NIHON DEMPA KOGYO CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0027] exist Figure 7 In the example of VCXO, if the control voltage is 0 to 4V, it can operate, but if it is more than 4V, it cannot operate

Method used

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  • Oscillation frequency control circuit
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  • Oscillation frequency control circuit

Examples

Experimental program
Comparison scheme
Effect test

Embodiment approach 1

[0115] "Other Embodiment 1"

[0116] In addition, in the above-mentioned example, the pulse output from the PWM circuit 22 is generated based on the latest control voltage information detected by the level detection circuit 23, but it is also possible to store default (default) voltage information, and based on the default voltage The information corresponds to the PWM duty cycle to output the information generated by the pulse.

[0117] Specifically, the memory 21 stores a center voltage value within an appropriate range of the control voltage for the voltage-controlled oscillator 15, and the corresponding PWM duty ratio is 50%. Therefore, if the voltage-controlled oscillator 14 The control voltage operates from 0 to 3.3V, and the control voltage is set to 3.3 / 2V. In addition, any voltage value other than the center voltage value may be stored and the corresponding control voltage may be set.

[0118] If the default voltage information is used, the components of the level d...

Embodiment approach 2

[0127] "Other Embodiment 2"

[0128] Furthermore, as another embodiment (another embodiment 2), this circuit has a configuration corresponding to the above-mentioned change over time. refer to Figure 5 This other second embodiment will be described. Figure 5 It is a schematic diagram of the aging change characteristic table.

[0129] In this circuit, the voltage / PWM duty ratio table is stored in the memory 21, but instead of this table, the Figure 5 table of time-varying characteristics.

[0130] Figure 5 In the relationship between the voltage information and the PWM duty ratio in the time-dependent change characteristic table, a time factor is further set.

[0131] Specifically, appropriate voltage information is set with respect to the elapse of time, and a PWM duty ratio is set corresponding to the voltage information and stored in a table.

[0132] The CPU 20 includes a timer inside, and measures the elapse of time.

[0133]In other Embodiment 2, when the detec...

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Abstract

Provided is an oscillation frequency control circuit, which corrects its own frequency so that it can hold an oscillation frequency stably even when it does not have an input of a highly stable reference signal but makes a self-run. The oscillation frequency control circuit comprises a voltage-controlled oscillator (15), a frequency divider (16), a phase comparator (12), a loop filter (14), a detecting circuit (17) for detecting an external reference signal, a PWM circuit (22) for generating pulses, when pulse generating information inputs, to output the pulses to the loop filter (14), a memory (21) for storing the pulse generating information corresponding to voltage information, a switch (13) for turning ON / OFF the connection between the phase comparator (12) and the loop filter (14), and a CPU (20) for turning ON the switch (13), if the level of the external reference signal detected by the detecting circuit (17) is within a proper range, but OFF the switch (13), if the level is outside of the proper range, thereby to output the pulse generating information stored in the memory (21), to the PWM circuit (22).

Description

technical field [0001] The present invention relates to an oscillation frequency control circuit of an oscillator, and particularly relates to an oscillation frequency control circuit which corrects its own frequency synchronously with an output signal and ensures stability for a certain period even when there is no stable reference signal. Background technique [0002] In base stations such as next-generation mobile communications and terrestrial digital broadcasting, the accuracy required for frequency reference signals is gradually increasing. [0003] In systems in the fields of broadcasting and communication, cesium frequency reference oscillators, rubidium frequency reference oscillators, frequency synchronization type reference oscillators using GPS signals, and the like are used as frequency reference signals. [0004] However, these oscillators are generally more expensive, so the reference signal from these oscillators is distributed and used as the reference signa...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03L7/14H03L7/093H03L7/095
CPCH03L7/095H03L7/146H03L7/14H03L7/093
Inventor 大西直树
Owner NIHON DEMPA KOGYO CO LTD