Oscillator frequency calibration circuit and frequency calibration method thereof

Abstract

The invention discloses a frequency calibration circuit for an oscillator. The frequency calibration circuit comprises a state machine module, a reference clock counter, a frequency division clock counter and a capacitance word selection module, wherein the state machine module is used for receiving a calibration starting signal, then outputting a counting starting signal, and controlling the transfer of a state relation; the reference clock counter is used for receiving the counting starting signal, then starting counting, and feeding back an oscillator delay completion bit signal to the state machine module; the frequency division clock counter is used for receiving the counting starting signal and then starting counting; and the capacitance word selection module is used for storing the counting values of the reference clock counter and the frequency division clock counter and determining an optimal capacitance control word by adopting a preset algorithm. The invention further discloses a frequency calibration method for an oscillator. The frequency calibration circuit and method effectively improve the frequency calibration precision without increasing a switching capacitor array.

Description

technical field [0001] The invention relates to the technical field of integrated circuit design, in particular to a frequency calibration circuit of an oscillator and a frequency calibration method thereof, in which an optimal capacitor control word is determined based on a phase-locked loop dichotomy. Background technique [0002] A phase-locked loop is a key module in radio frequency communication systems and is used to provide a stable frequency for transceivers. The phase-locked loop circuit is a feedback control circuit, which uses the input reference clock provided by the external crystal oscillator to control the frequency and phase of the internal oscillation signal of the loop, so as to obtain the required frequency signal. The classic phase-locked loop circuit consists of a frequency detector, a charge pump, a loop filter, a voltage-controlled oscillator, and a frequency divider. To achieve fractional frequency division, a sigma-delta modulator is also required. ...

AI Technical Summary

Problems solved by technology

The traversal method can go from high to low, or from low to high, until the target value is found. The disadvantage is that when there are many states, it will take a long time

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