Method and apparatus for oscillation frequency compensation and phase lock loop circuit

Abstract

The embodiment of the invention discloses a compensation method and a device of oscillation frequency and a phase-locked loop circuit, belonging to the technical field of circuit compensation. The method is applied to LC oscillating circuits, including the following steps: voltage control signals are accessed at one end of a variable capacitor in an LC oscillating circuit, and oscillator signals are generated in the oscillating circuit by the voltage control signals; a variable bias voltage reflecting external parameter variation is obtained; the variable bias voltage is accessed at the otherend of the variable capacitor; and the oscillation frequency variation of the oscillator signals generated by the LC oscillating circuit is compensated by the variable bias voltage. The device comprises a generation module, an obtaining module and a compensation module. The circuit comprises a phase discriminator, a low-pass filter and a voltage controlled oscillator; and the voltage controlled oscillator comprises the LC oscillating circuit having at least one variable capacitor, the generation module and the obtaining module. The embodiment of the invention compensates the variation of oscillation frequency of the circuit containing the LC oscillating circuit by applying the bias voltage to one end of the variable capacitor of the LC oscillating circuit, thereby improving the stability of circuit oscillation frequency.

Description

Technical field [0001] The present invention relates to the technical field of circuit compensation, in particular to a method and device for compensating oscillation frequency and a phase-locked loop circuit. Background technique [0002] The PLL circuit (Phase Locked Loop, phase locked loop circuit) is a loop control system that generates a voltage controlled oscillator control signal from the phase difference between the reference frequency and the output frequency, thereby adjusting the output frequency until the output frequency reaches the expected value. In the PLL circuit, VCO (Voltage Controlled Oscillator, voltage controlled oscillator) is an important part of it, and is generally used to generate a clock. Such as figure 1 In a common on-chip integrated VCO circuit shown, L, C1, and C2 form a resonant circuit, and C1 and C2 are variable capacitors. MN1, MN2, MP1, and MP2 constitute two pairs of negative resistance transistors. MP3 is a current source tube. Among them, ...

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Problems solved by technology

The PLL is a closed-loop system. When the power supply voltage and temperature change sharply, the oscillation frequency of the VCO will change in a large range, which will cause the PLL to lose lock; when the voltage and temperature change are not very fast, the negative feedback of the PLL will Automatically adjust the input voltage of the VCO to keep its output frequency unchanged, but this actually increases the input voltage range of the VCO and increases the difficulty of circuit design

From another point of view, due to the influence of voltage or temperature, when the VCO input voltage range remains unchanged, the VCO oscillation frequency range is also reduced

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