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A second-order switch low-pass filter in a charge pump phase-locked loop and a locking method using the second-order switch low-pass filter to realize the loop

A low-pass filter and low-pass filtering technology, which is applied in the direction of electrical components, automatic power control, etc., can solve the problem of large VCO control voltage jitter

Active Publication Date: 2018-04-24
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The invention aims to solve the problem of large VCO control voltage jitter caused by shortening the locking time of the phase-locked loop by increasing the loop bandwidth in the existing way

Method used

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  • A second-order switch low-pass filter in a charge pump phase-locked loop and a locking method using the second-order switch low-pass filter to realize the loop
  • A second-order switch low-pass filter in a charge pump phase-locked loop and a locking method using the second-order switch low-pass filter to realize the loop
  • A second-order switch low-pass filter in a charge pump phase-locked loop and a locking method using the second-order switch low-pass filter to realize the loop

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specific Embodiment approach 1

[0043] Specific implementation mode one: refer to Image 6 Specifically illustrate this embodiment, the second-order switch low-pass filter in the charge pump phase-locked loop described in this embodiment, it comprises second-order switch low-pass filter unit 1 and switch control unit 2,

[0044] The Icp signal input end of the second-order switch low-pass filter unit 1 is connected to the Icp signal output end of the previous stage structure charge pump 11, and the Vctrl1 signal input end of the second-order switch low-pass filter unit 1 is connected to the Vctrl1 signal of the switch control unit 2 output, second-order switching low-pass filter unit 1 The signal input terminal is connected to the switch control unit 2 signal output,

[0045] The UP signal output terminal of the frequency and phase detector is used as the UP signal input terminal of the switch control unit 2,

[0046] The DW signal output terminal of the frequency and phase detector is used as the DW si...

specific Embodiment approach 2

[0048] Specific implementation mode two: refer to Figure 7 Describe this embodiment in detail. This embodiment is a further description of the second-order switch low-pass filter in the charge pump phase-locked loop described in the first embodiment. In this embodiment, the second-order switch low-pass filter unit 1 includes CMOS switch 3, resistor R1, capacitor C1 and capacitor C2,

[0049] The switch control unit 2 includes a pulse width identification unit 7, a NAND gate 8, a NOR gate 9 and an inverter 10,

[0050] The Icp signal output end of the charge pump 11 in the previous stage structure is connected to one end of the resistor R1 and a signal input end of the CMOS switch 3 at the same time, the other end of the resistor R1 is connected to one end of the capacitor C1, and the other end of the capacitor C1 is connected to the power ground.

[0051] The Vctrl signal output end of the CMOS switch 3 is connected to one end of the capacitor C2, and the other end of the ca...

specific Embodiment approach 3

[0057] Specific implementation mode three: refer to Figure 7 This embodiment is described in detail. This embodiment is a further description of the second-order switch low-pass filter in the charge pump phase-locked loop described in the first embodiment. In this embodiment, the charge pump (11) includes a No. 1 voltage Source U1, No. 2 voltage source U2, No. 1 switch K1 and No. 2 switch K2,

[0058] The positive pole of the No. 1 voltage source U1 is connected to the power supply, the negative pole of the No. 1 voltage source U1 is connected to one end of the No. 1 switch K1, the other end of the No. 1 switch K1 is connected to one end of the No. 2 switch K2, and the other end of the No. 2 switch K2 is connected to The positive pole of the second voltage source U2, the control terminal of the first switch K1 is connected to the UP signal input terminal of the frequency and phase detector, and the control terminal of the second switch K2 is connected to the DW signal input t...

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Abstract

The invention discloses a second-order switch low-pass filter in a charge pump phase-locked loop and a loop locking method using the second-order switch low-pass filter, and relates to the field of fast locking of a charge pump phase-locked loop. The invention aims to solve the problem of large VCO control voltage jitter caused by shortening the locking time of the phase-locked loop by increasing the loop bandwidth in the prior art. The Icp signal output end of the charge pump is used as the Icp signal input end of the second-order switch low-pass filter unit, and the Vctr11 signal output end and the signal output end of the second-order switch low-pass filter unit Vctrl1 signal input end are respectively connected to the switch control unit. The UP and DW signals are used as the input terminals of the switch control unit, and the pulse width identification unit is used to identify the pulse width output by the frequency and phase detector of the charge pump phase-locked loop, so as to ensure that the frequency and phase detector can accurately adjust the VCO control voltage and realize shortening. lock time. It can be used in charge pump phase locked loop system.

Description

technical field [0001] The invention relates to the situation that the VCO control voltage fluctuates greatly due to increasing the loop bandwidth in the phase-locked loop circuit of the charge pump to shorten the locking time. The invention belongs to the fast locking field of a charge pump phase-locked loop. Background technique [0002] charge pump phase-locked loop systems, such as figure 1 As shown, the reference signal enters the input terminal of the phase frequency detector (PFD), and the two signals output by the phase frequency detector are the UP signal and the DW signal, and the two signals are input to the charge pump (CP), and the charge pump Output Icp signal, the signal enters the loop filter (LPF), the filter signal output end of the loop filter is connected to the filter signal input end of the voltage-controlled oscillator (VCO), and the output end of the voltage-controlled oscillator outputs the oscillation signal Enter the input terminal of the frequen...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H03L7/08
Inventor 王永生杜云飞来逢昌刘晓为
Owner HARBIN INST OF TECH