CN-122026901-A - Circuit structure for quick locking of phase-locked loop and control method thereof

CN122026901ACN 122026901 ACN122026901 ACN 122026901ACN-122026901-A

Abstract

The invention provides a circuit structure for quick locking of a phase-locked loop and a control method thereof, wherein the circuit structure comprises: the fast locking loop filter comprises a capacitive digital-to-analog conversion module. The invention adopts the capacitance type digital-to-analog converter module, can rapidly and accurately set the control voltage of the voltage-controlled oscillator based on the charge sharing principle, thereby realizing rapid locking, and the structure multiplexes the capacitance in the loop filter without additional area. The invention has the advantages of high precision, low power consumption and low cost, and has extremely high application value and potential.

Inventors

ZHANG LINGHAN
LUO WEI
ZHOU JIMING
Mao Yinwei

Assignees

圭步微电子(南京)有限公司

Dates

Publication Date: 20260512
Application Date: 20251229

Claims (6)

1. The circuit structure is characterized by comprising a voltage-controlled oscillator, a frequency divider, a phase discriminator and a quick locking loop filter, wherein an output port of the frequency divider and an external reference source are respectively connected with two input ports of the phase discriminator, the output port of the phase discriminator is connected with the input port of the quick locking loop filter, the output port of the loop filter is connected with the input port of the voltage-controlled oscillator, and the output port of the voltage-controlled oscillator is connected with the input port of the frequency divider; The fast locking loop filter comprises a resistor R0, a resistor R1, a capacitor C2 and a capacitor type digital-to-analog conversion module, wherein a first port of the resistor R0 is connected with a first port of the capacitor C1 and a first port of the resistor R1, a second port of the resistor R0 is connected with the first port of the capacitor type digital-to-analog conversion module, a second port of the capacitor type digital-to-analog conversion module is grounded, a third port of the capacitor type digital-to-analog conversion module is connected with a power supply, a second port of the capacitor C1 is grounded, a second port of the resistor R1 is connected with the first port of the capacitor C2, the second port of the capacitor C2 is grounded, the capacitor type digital-to-analog conversion module further comprises N digital control ports, and input control signals of the digital control ports comprise three states, namely a capacitor state, a grounding state and a power supply state.
2. The circuit structure of claim 1, wherein the first port of the resistor R0 is an input port of the fast lock loop filter, and the second port of the resistor R1 is an output port of the fast lock loop filter.
3. The circuit configuration of claim 1, wherein the capacitive digital-to-analog converter module comprises N subunits, the first port of each subunit being connected to each other to form a first port of the capacitive digital-to-analog converter module, the second port of each subunit being connected to each other to form a second port of the capacitive digital-to-analog converter module, the third port of each subunit being connected to each other to form a third port of the capacitive digital-to-analog converter module, the digital control port of the i-th subunit forming an i-th digital control port of the capacitive digital-to-analog converter module.
4. The circuit structure according to claim 3, wherein each subunit comprises a capacitor Cu and a capacitor connection selection module, the first port of the capacitor Cu is connected to the second port of the capacitor connection selection module, the second port of the capacitor Cu forms the second port of the subunit, the third port of the capacitor Cu is connected to the power supply, the first port of the capacitor connection selection module forms the digital control port of the subunit, the first port of the capacitor Cu is controlled by the capacitor connection selection module to be connected to the first port of the subunit when the digital control port is in a capacitor state, the first port of the capacitor Cu is controlled by the capacitor connection selection module to be grounded when the digital control port is in a ground state, and the first port of the capacitor Cu is controlled by the capacitor connection selection module to be connected to the power supply when the digital control port is in a power supply state.
5. A method for controlling a circuit structure for fast locking of a phase locked loop, characterized in that the circuit structure for fast locking of a phase locked loop according to any one of claims 1-4 comprises the steps of: When the filter is in the capacitance state of the common loop filter, the control capacitance type digital-to-analog converter module is equivalent to a common capacitor; when the initial value of the control voltage needs to be set quickly: Setting the digital control ports of k subunits in the capacitive digital-to-analog converter module to be in a power-on state and setting the digital control ports of the rest N-k subunits to be in a grounding state according to the target control voltage required to be set; Setting the digital control ports of all N subunits in the capacitive digital-to-analog converter module to be in a capacitance state, and finally changing the control voltage to be a target voltage value, and switching the capacitive digital-to-analog converter module to be in a capacitance state of a common loop filter after the phase-locked loop is locked.
6. The method of claim 5, wherein the controlling the capacitor type digital-to-analog converter module is equivalent to a common capacitor by setting N control signals S of the capacitor type digital-to-analog converter module to be in a capacitor state, and the first ports of the capacitors Cu in all the subunits are connected with the second port of the resistor R0 in the loop filter.

Description

Circuit structure for quick locking of phase-locked loop and control method thereof Technical Field The invention belongs to the technical field of electronic circuits, relates to a phase-locked loop circuit technology, and particularly relates to a circuit structure for quickly locking a phase-locked loop and a control method thereof. Background A phase locked loop is a feedback control system that uses a voltage generated by phase synchronization to adjust a voltage controlled oscillator to generate a target frequency. The lock time of the phase locked loop refers to the time required for the phase locked loop to jump from one target frequency to another. The shorter the locking time is, the faster the system completes the frequency switching, so that the running efficiency of the whole system can be improved. The lock time of the phase locked loop is mainly limited by the loop bandwidth, and higher loop bandwidths can significantly reduce the lock time. But a higher loop bandwidth deteriorates the phase noise of the phase locked loop output frequency signal, reducing the frequency accuracy. How to reduce the lock time of a phase locked loop without affecting the phase noise in its locked state is a difficulty in the design of the phase locked loop circuit. Therefore, how to design a phase-locked loop structure that can realize fast locking and has the characteristics of low power consumption and low cost is a problem to be solved in the field. Disclosure of Invention In order to solve the above problems, the present invention discloses a circuit structure for realizing fast locking of a phase-locked loop and a control method thereof, which can reduce the time required for switching the frequency of the phase-locked loop with low cost and low power consumption, and does not deteriorate the output phase noise of the locked state of the phase-locked loop. In order to achieve the above purpose, the technical scheme of the invention is as follows: The circuit structure comprises a voltage-controlled oscillator, a frequency divider, a phase discriminator and a quick locking loop filter, wherein an output port of the frequency divider and an external reference source are respectively connected with two input ports of the phase discriminator, the output port of the phase discriminator is connected with the input port of the quick locking loop filter, the output port of the loop filter is connected with the input port of the voltage-controlled oscillator, and the output port of the voltage-controlled oscillator is connected with the input port of the frequency divider; The fast locking loop filter comprises a resistor R0, a resistor R1, a capacitor C2 and a capacitor type digital-to-analog conversion module, wherein a first port of the resistor R0 is connected with a first port of the capacitor C1 and a first port of the resistor R1, a second port of the resistor R0 is connected with the first port of the capacitor type digital-to-analog conversion module, a second port of the capacitor type digital-to-analog conversion module is grounded, a third port of the capacitor type digital-to-analog conversion module is connected with a power supply, a second port of the capacitor C1 is grounded, a second port of the resistor R1 is connected with the first port of the capacitor C2, the second port of the capacitor C2 is grounded, the capacitor type digital-to-analog conversion module further comprises N digital control ports, and input control signals of the digital control ports comprise three states, namely a capacitor state, a grounding state and a power supply state. Further, the first port of the resistor R0 is an input port of the fast lock loop filter, and the second port of the resistor R1 is an output port of the fast lock loop filter. Further, the capacitive digital-to-analog converter module includes N subunits, the first port of each subunit is connected to each other to form a first port of the capacitive digital-to-analog converter module, the second port of each subunit is connected to each other to form a second port of the capacitive digital-to-analog converter module, the third port of each subunit is connected to each other to form a third port of the capacitive digital-to-analog converter module, and the digital control port of the i-th subunit forms an i-th digital control port of the capacitive digital-to-analog converter module. Further, each subunit comprises a capacitor Cu and a capacitor connection selection module, wherein the first port of the capacitor Cu is connected with the second port of the capacitor connection selection module, the second port of the capacitor Cu forms the second port of the subunit, the third port of the capacitor Cu is connected with a power supply, the first port of the capacitor connection selection module forms a digital control port of the subunit, when the digital control port is in a capacitor state, the first port of the capacitor Cu is controlled by the capaci