초록 ▼

A phase lock circuit has a signal path to which a phase comparator, a loop filter and a voltage control oscillator are connected in series, the phase comparator being adapted to compare the phase of an input signal VIN with the phase in the output signal of the voltage control oscillator and to outp

A phase lock circuit has a signal path to which a phase comparator, a loop filter and a voltage control oscillator are connected in series, the phase comparator being adapted to compare the phase of an input signal VIN with the phase in the output signal of the voltage control oscillator and to output its result of comparison, the loop filter being adapted to receive the output signal of the phase comparator and to output a DC voltage; the voltage control oscillator being adapted to control the output oscillation frequency depending on the DC output voltage of the loop filter, the phase lock circuit further comprising voltage tracking means for adding, to the voltage of the signal path, a signal causing the average voltage in the output voltage of the phase comparator to coincide with a predetermined reference voltage, whereby the voltage tracking means can enlarge the lock range in the phase lock circuit.

대표청구항 ▼

What is claimed is: 1. A phase lock circuit (phase-locked loop circuit) having a signal path to which a phase comparator, a loop filter and a voltage control oscillator (voltage-controlled oscillator) are connected in series, said phase comparator being adapted to compare the phase of an input sign

What is claimed is: 1. A phase lock circuit (phase-locked loop circuit) having a signal path to which a phase comparator, a loop filter and a voltage control oscillator (voltage-controlled oscillator) are connected in series, said phase comparator being adapted to compare the phase of an input signal VIN with the phase in the output signal of said voltage control oscillator and to output its result of comparison, said loop filter being adapted to receive the output signal of said phase comparator and to output a Direct Current (DC) voltage; said voltage control oscillator being adapted to control the output oscillation frequency depending on the DC output voltage of said loop filter, said phase lock circuit further comprising voltage tracking circuit for adding, to the voltage of said signal path, a signal causing the average voltage in the output voltage of said phase comparator to coincide with a predetermined reference voltage, whereby said voltage tracking circuit can enlarge the lock range in said phase lock circuit wherein said voltage tracking circuit comprises reference voltage generator means for generating a voltage within the output voltage range of said phase comparator, a differential amplifier for outputting a voltage proportional to a difference between the output voltage of said phase comparator and the output voltage of said reference voltage generator means, a filter for converting the output of said differential amplifier into DC voltage, and adder means for adding the output of said filter to the output voltage of said phase comparator and for outputting the result to said loop filter. 2. A phase lock circuit (phase-locked loop circuit) having a signal path to which a phase comparator, a loop filter, a voltage control oscillator (voltage-controlled oscillator), a lock detector and a retraction circuit are connected, said phase comparator being adapted to compare the phase of an input signal VIN with the phase in the output signal of said voltage control oscillator and to output its result of comparison, said loop filter being adapted to receive the output signal of said phase comparator and to output a Direct Current (DC) voltage, said voltage control oscillator being adapted to control the output oscillation frequency depending on the DC output voltage of said loop filter, said lock detector being adapted to judge whether the output signal of the said voltage control oscillator is locked or unlocked relative to said input signal VIN and to output the judgment result, said retraction circuit being a signal generator which is adapted to a scanning signal if said lock detector judges the unlocked state and to add the scanning signal to the voltage of said signal path, said phase lock circuit further comprising voltage tracking circuit for adding, to the voltage of said signal path, a signal causing the average voltage in the output voltage of said phase comparator to coincide with a predetermined reference voltage, whereby said voltage tracking circuit can enlarge the lock range in said phase lock circuit wherein said voltage tracking circuit comprises reference voltage generator means for generating a voltage within the output voltage range of said phase comparator, a differential amplifier for outputting a voltage proportional to a difference between the output voltage of said phase comparator and the output voltage of said reference voltage generator means, a filter for converting the output of said differential amplifier into DC voltage, and adder means for adding the output of said filter to the output voltage of said phase comparator and for outputting the result to said loop filter. 3. A phase lock circuit (phase-locked loop circuit) having a signal path to which a phase comparator, a loop filter and a voltage control oscillator (voltage-controlled oscillator) are connected in series, said phase comparator being adapted to compare the phase of an input signal VIN with the phase in the output signal of said voltage control oscillator and to output its result of comparison, said loop filter being adapted to receive the output signal of said phase comparator and to output a Direct Current (DC) voltage; said voltage control oscillator being adapted to control the output oscillation frequency depending on the DC output voltage of said loop filter, said phase lock circuit further comprising voltage tracking circuit for adding, to the voltage of said signal path, a signal causing the average voltage in the output voltage of said phase comparator to coincide with a predetermined reference voltage, whereby said voltage tracking circuit can enlarge the lock range in said phase lock circuit wherein said voltage tracking circuit comprises reference voltage generator means for generating a voltage within the output voltage range of said phase comparator, a differential integrator for outputting a voltage proportional to a difference between the output voltage of said phase comparator and the output voltage of said reference voltage generator means, and adder means for adding the output of said differential integrator to the output voltage of said phase comparator and for outputting the result to said loop filter. 4. A phase lock circuit (phase-locked loop circuit) having a signal path to which a phase comparator, a loop filter, a voltage control oscillator (voltage-controlled oscillator), a lock detector and a retraction circuit are connected, said phase comparator being adapted to compare the phase of an input signal VIN with the phase in the output signal of said voltage control oscillator and to output its result of comparison, said loop filter being adapted to receive the output signal of said phase comparator and to output a Direct Current (DC) voltage; said voltage control oscillator being adapted to control the output oscillation frequency depending on the DC output voltage of said loop filter, said lock detector being adapted to judge whether the output signal of the said voltage control oscillator is locked or unlocked relative to said input signal VIN and to output the judgment result, said retraction circuit being a signal generator which is adapted to a scanning signal if said lock detector judges the unlocked state and to add the scanning signal to the voltage of said signal path, said phase lock circuit further comprising voltage tracking circuit for adding, to the voltage of said signal path, a signal causing the average voltage in the output voltage of said phase comparator to coincide with a predetermined reference voltage, whereby said voltage tracking circuit can enlarge the lock range in said phase lock circuit wherein said voltage tracking circuit comprises reference voltage generator means for generating a voltage within the output voltage range of said phase comparator, a differential integrator for outputting a voltage proportional to a difference between the output voltage of said phase comparator and the output voltage of said reference voltage generator means, and adder means for adding the output of said differential integrator to the output voltage of said phase comparator and for outputting the result to said loop filter. 5. The phase lock circuit according to claim 1 or 3 wherein the Direct Current (DC) voltage converted from the output voltage of said phase comparator by another filter is inputted into said voltage tracking circuit. 6. The phase lock circuit according to claim 2 or 4 wherein the DC voltage converted from the output voltage of said phase comparator by another filter is inputted into said voltage tracking circuit. 7. The phase lock circuit according to claim 1 or 3 wherein said reference voltage generator means comprises delay means for delaying said input signal VIN for a predetermined time period, and a second phase comparator for receiving said input signal VIN and the output of said delay means. 8. The phase lock circuit according to claim 2 or 4 wherein said reference voltage generator means comprises delay means for delaying said input signal VIN for a predetermined time period, and a second phase comparator for receiving said input signal VIN and the output of said delay means. 9. The phase lock circuit according to claim 1 or 3 wherein said reference voltage generator means comprises delay means for delaying the output signal of said voltage control oscillator for a predetermined time period and a second phase comparator for receiving the output signal of said voltage control oscillator and the output signal of said delay means. 10. The phase lock circuit according to claim 2 or 4 wherein said reference voltage generator means comprises delay means for delaying the output signal of said voltage control oscillator for a predetermined time period and a second phase comparator for receiving the output signal of said voltage control oscillator and the output signal of said delay means. 11. The phase lock circuit according to claim 1 or 3 wherein said addition is carried out relative to the DC output voltage of said loop filter in said signal path. 12. The phase lock circuit according to claim 2 or 4 wherein said addition is carried out relative to the DC output voltage of said loop filter in said signal path. 13. A phase lock circuit (phase-locked loop circuit) having a signal path to which a phase comparator, a loop filter and a voltage control oscillator (voltage-controlled oscillator) are connected in series, said phase comparator being adapted to compare the phase of an input signal VIN with the phase in the output signal of said voltage control oscillator and to output its result of comparison, said loop filter being adapted to receive the output signal of said phase comparator and to output a Direct Current (DC) voltage; said voltage control oscillator being adapted to control the output oscillation frequency depending on the DC output voltage of said loop filter, said phase lock circuit further comprising voltage tracking circuit for adding, to the voltage of said signal path, a signal causing the average voltage in the output voltage of said phase comparator to coincide with a predetermined reference voltage, whereby said voltage tracking circuit can enlarge the lock range in said phase lock circuit wherein said voltage tracking circuit comprises reference voltage generator means for generating a voltage within the output voltage range of said phase comparator, voltage difference detector means for detecting a potential difference between the output voltage of said phase comparator and the output voltage of said reference voltage generator means when it exceeds a predetermined value, voltage comparator means for detecting a voltage difference between the output voltage of said phase comparator and the output voltage of said reference voltage generator means, pulse generator means for performing an oscillation when the voltage difference detector means detects that the potential difference between the output voltage of said phase comparator and the output voltage of said reference voltage generator means exceeds said predetermined value, counter means for counting the output of said pulse generator means, the direction of counting being controlled by the output of said voltage comparison means, and Digital-to-Analog (D/A) converter means for converting the result of count from said counter means into a voltage. 14. A phase lock circuit (phase-locked loop circuit) having a signal path to which a phase comparator, a loop filter, a voltage control oscillator (voltage-controlled oscillator), a lock detector and a retraction circuit are connected, said phase comparator being adapted to compare the phase of an input signal VIN with the phase in the output signal of said voltage control oscillator and to output its result of comparison, said loop filter being adapted to receive the output signal of said phase comparator and to output a Direct Current (DC) voltage; said voltage control oscillator being adapted to control the output oscillation frequency depending on the DC output voltage of said loop filter, said lock detector being adapted to judge whether the output signal of the said voltage control oscillator is locked or unlocked relative to said input signal VIN and to output the judgment result, said retraction circuit being a signal generator which is adapted to a scanning signal if said lock detector judges the unlocked state and to add the scanning signal to the voltage of said signal path, said phase lock circuit further comprising voltage tracking circuit for adding, to the voltage of said signal path, a signal causing the average voltage in the output voltage of said phase comparator to coincide with a predetermined reference voltage, whereby said voltage tracking circuit can enlarge the lock range in said phase lock circuit wherein said voltage tracking circuit comprises reference voltage generator means for generating a voltage within the output voltage range of said phase comparator, voltage difference detector means for detecting a potential difference between the output voltage of said phase comparator and the output voltage of said reference voltage generator means when it exceeds a predetermined value, voltage comparator means for detecting a voltage difference between the output voltage of said phase comparator and the output voltage of said reference voltage generator means, pulse generator means for performing an oscillation when the voltage difference detector means detects that the potential difference between the output voltage of said phase comparator and the output voltage of said reference voltage generator means exceeds said predetermined value, counter means for counting the output of said pulse generator means, the direction of counting being controlled by the output of said voltage comparison means, and Digital-to-Analog (D/A) converter means for converting the result of count from said counter means into a voltage. 15. The phase lock circuit according to claim 2 or 4 wherein said retraction circuit comprises pulse generator means for continuing pulses with a predetermined cycle when said lock detector means detects the unlock, counter means for counting the number of pulses from said pulse generator means, and D/A converter means for converting the result of count from said counter means into a voltage. 16. The phase lock circuit according to claim 2 or 4 wherein said retraction circuit comprises Schmitt trigger means, integration means for integrating the output voltage of said Schmitt trigger means and for feeding the result of integration back to the input of said Schmitt trigger means, and voltage holding means for outputting the output voltage of said integration means when said lock detector means judges the unlock and for outputting a constant voltage when said lock detector means judges the lock. 17. The phase lock circuit according to claim 2 or 4 wherein said retraction means comprises Schmitt trigger means for receiving the output voltage of said voltage tracking circuit, and circuit switching means for feeding the output of said Schmitt trigger means to said voltage tracking circuit when said lock detector means detects the unlock and for feeding the output of said phase comparator to the input of said voltage tracking circuit when said lock detector means detects the lock. 18. The phase lock circuit according to claim 2 or 4 wherein said retraction circuit wherein at least one of the pulse generator means, counter means and Digital-to-Analog (D/A) converter means included in said retraction circuit and the pulse generator means, counter means and D/A converter means included in said voltage tracking circuit is shared by said retraction circuit and voltage tracking circuit. 19. The phase lock circuit according to claim 1 or 3 wherein said reference voltage generator means comprises variably delay means for delaying said input signal VIN for any time period, oscillation means for oscillating a signal having a predetermined frequency to periodically control the delay in said variable delay means, and a second phase comparator for comparing the phase of said input signal VIN with the phase in the output signal of said variable delay means. 20. The phase lock circuit according to claim 2 or 4 wherein said reference voltage generator means comprises variably delay means for delaying said input signal VIN for any time period, oscillation means for oscillating a signal having a predetermined frequency to periodically control the delay in said variable delay means, and a second phase comparator for comparing the phase of said input signal VIN with the phase in the output signal of said variable delay means. 21. The phase lock circuit according to claim 1 or 3 wherein said reference voltage generator means comprises oscillation means for oscillating a signal having a predetermined frequency, and a second phase comparator for comparing the phase of said input signal VIN with the phase in the output signal of said oscillation means. 22. The phase lock circuit according to claim 2 or 4 wherein said reference voltage generator means comprises oscillation means for oscillating a signal having a predetermined frequency, and a second phase comparator for comparing the phase of said input signal VIN with the phase in the output signal of said oscillation means.