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A phase-locked loop including a phase comparator, a charging/discharging unit, a low pass filter, a controlled oscillator, and a feedback unit is provided. The charging/discharging unit outputs a control signal according to the result of the phase comparator. The charging/discharging unit includes a

A phase-locked loop including a phase comparator, a charging/discharging unit, a low pass filter, a controlled oscillator, and a feedback unit is provided. The charging/discharging unit outputs a control signal according to the result of the phase comparator. The charging/discharging unit includes a compensation unit for compensating the control signal according to a compensation value. The controlled oscillator is electrically connected to the low pass filter and outputs an output signal. The controlled oscillator includes a copy unit which is electrically connected to the compensation unit to determine the compensation value according to an internal current of the controlled oscillator.

대표청구항 ▼

What is claimed is: 1. A phase-locked loop, comprising: a phase comparator, for receiving an input signal and a feedback signal to compare phases of the input signal and the feedback signal; a charging/discharging unit, connected to the phase comparator, for outputting a control signal according to

What is claimed is: 1. A phase-locked loop, comprising: a phase comparator, for receiving an input signal and a feedback signal to compare phases of the input signal and the feedback signal; a charging/discharging unit, connected to the phase comparator, for outputting a control signal according to a comparison result of the phase comparator, wherein the charging/discharging unit comprises a compensation unit for compensating the control signal according to a first compensation value; a low pass filter, connected to the charging/discharging unit, for filtering the control signal output from the charging/discharging unit; a controlled oscillator, connected to the low pass filter, for converting the control signal filtered by the low pass filter to a control current and determining a frequency of an output signal according to the control current, wherein the controlled oscillator comprises a copy unit, connected to the compensation unit, for generating a plurality of candidate currents by copying the control current so as to determine the first compensation value by switching the candidate currents; and a feedback unit, connected to the controlled oscillator, for providing the feedback signal to the phase comparator according to the output signal. 2. The phase-locked loop as claimed in claim 1, wherein the charging/discharging unit further comprises a charging/discharging controller, connected to the compensation unit, the phase comparator, and the low pass filter, for determining and generating the control signal according to the comparison result of the phase comparator and the output of the compensation unit. 3. The phase-locked loop as claimed in claim 2, wherein the charging/discharging controller comprises: a first switch, connected to a first voltage by a first terminal of the first switch, for determining a connection state of the first switch according to the comparison result of the phase comparator; a charging current source, connected to a second terminal of the first switch by a first terminal of the charging current source, for determining a value of the current of the charging current source according to the output of the compensation unit, wherein a signal of a second terminal of the charging current source serving as the control signal; a discharging current source, connected to the second terminal of the charging current source by a first terminal of the discharging current unit, for determining the current value of the discharging current source according to the output of the compensation unit; and a second switch, connected to a second terminal of the discharging current source by a first terminal of the second switch and connected to a second voltage by a second terminal of the second switch, for determining a connection state of the second switch according to the comparison result of the phase comparator. 4. The phase-locked loop as claimed in claim 3, wherein the first voltage is a supply voltage, and the second voltage is a ground voltage. 5. The phase-locked loop as claimed in claim 3, wherein the compensation unit comprises: a first current source, including a first terminal connected to the first voltage; a second current source, including a first terminal connected to a second terminal of the first current source and an output of the copy unit, and a second terminal connected to the second voltage; a third current source, connected to the second voltage by the second terminal of the third current source, for determining the current value of the third current source according the second current source; and a fourth current source, including a first terminal connected to the first voltage, and a second terminal connected to a first terminal of the third current source; wherein the charging current source is determined according to the fourth current source, and the discharging current source is determined according to the second current source. 6. The phase-locked loop as claimed in claim 5, wherein the compensation unit further comprises: a first converting circuit, connected between the first terminal of the second current source and the low pass filter, for converting the control signal filtered by the low pass filter into a feedback current and transmitting the feedback current to the first terminal of the second current source. 7. The phase-locked loop as claimed in claim 1, wherein the low pass filter comprises: a resistor, electrically connected between the charging/discharging unit and the controlled oscillator by a first terminal of the resistor; a first capacitor, including a first terminal electrically connected to a second terminal of the resistor, and a second terminal of the first capacitor electrically connected to a third voltage; and a second capacitor, including a first terminal electrically connected to the first terminal of the resistor, and a second terminal electrically connected to the third voltage. 8. The phase-locked loop as claimed in claim 7, wherein the third voltage is the ground voltage. 9. The phase-locked loop as claimed in claim 1, wherein the controlled oscillator further comprises: a second converting circuit, for converting the control signal filtered by the low pass filter into the control current; and a current-controlled oscillation circuit, connected to the second converting circuit, for determining the frequency of the output signal according to the control current; wherein the copy unit is electrically connected to the second converting circuit for determining the first compensation value according to the control current. 10. The phase-locked loop as claimed in claim 9, wherein the second converting circuit comprises: a fifth current source, connected to a fourth voltage by a first terminal of the fifth current source, and connected the current-controlled oscillation circuit by a second terminal of the fifth current source, for outputting the control current, wherein the current of the fifth current source is determined according to the control signal. 11. The phase-locked loop as claimed in claim 10, wherein the fourth voltage is the supply voltage. 12. The phase-locked loop as claimed in claim 9, wherein the current-controlled oscillation circuit comprises: a NOT gate series, including an input terminal connected to an output terminal of the NOT gate series and providing the output signal from the output terminal of the NOT gate series, wherein the NOT gate series is formed by an odd number of NOT gates and an operating speed of the NOT gates is determined by the control current. 13. The phase-locked loop as claimed in claim 9, wherein the copy unit comprises: a plurality of candidate current sources, coupled to the second converting circuit, wherein each of the candidate current sources determines the current value thereof respectively according to the control current to generate the candidate currents; and a multiplexer, electrically connected to the candidate current sources, wherein the multiplexer selects one of the candidate currents generated by the candidate current sources as the first compensation value according to a second control signal. 14. The phase-locked loop as claimed in claim 9, wherein the copy unit comprises: a plurality of candidate current sources, coupled to the second converting circuit, wherein each of the candidate current sources determines the current value thereof according to the control current to generate the candidate currents; and a plurality of candidate switches, electrically connected to the plurality of candidate current sources respectively, wherein each of the candidate switches determines the connection state thereof according to a second control signal; wherein the copy unit determines to select at least one of the candidate currents according to the connection state of the candidate switches, and the sum of the selected candidate currents serves as the first compensation value.