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Circuit filter and lock phase circuit

A loop filter, phase-locked loop technology, applied in the direction of automatic power control, electrical components, multi-terminal network, etc., can solve the problems of capacitor occupation, large area, etc., and achieve the effect of large equivalent capacitance value

Active Publication Date: 2008-08-06
VIA TECH INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the larger the capacitance value of the loop filter, the larger the area occupied by the capacitor used

Method used

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  • Circuit filter and lock phase circuit
  • Circuit filter and lock phase circuit
  • Circuit filter and lock phase circuit

Examples

Experimental program
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Embodiment Construction

[0017] In order to make the above and other objects, features and advantages of the present invention more comprehensible, a preferred embodiment is exemplified below and described in detail in conjunction with the accompanying drawings.

[0018] figure 1 It is an embodiment of a loop filter. Such as figure 1 As shown, the loop filter 11A includes a capacitor C1 having a first terminal coupled to the node ND1 and a second terminal coupled to a ground terminal. For example, the terminal ND1 is the current pump of the phase-locked loop (such as Figure 7 shown), but not limited thereto.

[0019] Assuming that the voltage across capacitor C1 is V1, the current Ic flowing through capacitor C1 can be expressed as:

[0020] Ic = C 1 × dV 1 dt - - - ( 1 )

[0021] In other words, in...

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PUM

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Abstract

The invention relates to a loop filter and a phase-locking loop, wherein, the loop filter comprises a first resistor, a first capacitor, a second resistor, an operational amplifier and a second capacitor; the first resistor is provided with a first end which is coupled to a first node and a second end which is coupled to a second node; the first capacitor is coupled between the second node and earth voltage; the second resistor is provided with a first end which is coupled to the first node and a second end which is coupled to a third node; the operational amplifier is provided with an noninverting input end which is coupled to the second node, an inverted input end which is coupled to the third node, and an output end; the second capacitor is coupled between the output end of the operational amplifier and the third node. The loop filter and the phase-locking loop can provide the same equivalent capacitance values by using smaller area or provide large equivalent capacitance values by utilization of the same area.

Description

technical field [0001] The present invention relates to a loop filter, in particular to a loop filter capable of increasing capacitance. Background technique [0002] In current synchronous systems (such as computer systems and communication equipment), the clock generation circuit is a very important part. For example, a phase-locked loop (Phase Look Loop, PLL) circuit is widely used in frequency synthesis, timing correction, clock distribution, and phase demodulation. [0003] Generally speaking, a traditional phase locked loop includes a phase frequency detector (phase / frequency detector, PFD), a current pump (charge pump), a loop filter (loop filter), a voltage controlled oscillator (voltage controlloscillator, VCO) and a frequency divider (divider). The phase frequency detector compares the transitional edges of a feedback clock and a reference clock to generate a comparison signal to charge and discharge the current pump. Furthermore, the loop filter will generate a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03L7/08H03L7/089H03L7/093H03L7/18H03H11/12
Inventor 刘中鼎曲静然
Owner VIA TECH INC