Automatic regulating method and circuit for phase locking loop frequency synthesizer switch capacitor

Abstract

This invention relates to an automatic adjusting method and a realization circuit for the switch of a phase-locking loop frequency synthesizer switch capacitance, which changes the LC resonance structure of the voltage-controlled oscillator in a phase-locking loop frequency synthesizer to a structure of a variable capacitor and switch capacitor array and adds a switch capacitance control module for testing the voltage variance of the voltage-controlled oscillator to control the load of the switch capacitor and regulate the central frequency of the oscillator to get even better performance of synthesizers, said control module is composed of two hysteresis comparators and a FSM for regulating the switch, the input of the comparator is control voltage having high and low threshold voltages, the FSM controls the switch of the switch capacitor array.

Description

technical field [0001] The invention belongs to the technical field of radio frequency integrated circuits, and in particular relates to an automatic adjustment method and a realization circuit of a switching capacitor of a phase-locked loop frequency synthesizer. Background technique [0002] The huge market potential of portable wireless communication products has greatly promoted the development of radio frequency integrated circuit products. Various radio frequency communication protocols have emerged as the times require. They work in the frequency range from several hundred M to several G respectively, and their respective specification requirements are also different. But no matter what kind of standard wireless radio frequency communication products are used, they must use frequency synthesis technology to obtain local oscillator frequency (local oscillator, LO) or direct modulation transmission. A frequency synthesizer (frequencysynthesizer, FS) for this purpose ha...

AI Technical Summary

Problems solved by technology

This method has the following disadvantages: 1) two loops need to be designed, which greatly increases the hardware consumption of the circuit; Transient fluctuations are generated, thereby prolonging the locking time; 3) Once the circuit has large fluctuations due to changes in power supply voltage, etc., the loop must be switched from the working loop to the correction loop for re-calibration, thereby affecting the communication quality of the system

Images