Voltage-controlled oscillator comprising a circuit for compensating frequency pulling
AssigneeSTMicroelectronics S.r.l.
InventorPeter Nayler
Life of this patent
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Abstract
The present invention relates to a method for stabilising the operation of a voltage controlled oscillator (VCO) driven by a phase locked loop (PLL), the voltage controlled oscillator delivering an RF signal and receiving through at least one spurious path a harmonic component of a frequency equal or proximate to that of the RF signal, capable of disturbing its operation by injection pulling. According to the present invention, the method comprises a step of injecting into the voltage controlled oscillator an injection pulling compensation signal, the phase and the amplitude of which are adjusted so as to neutralise the effects of the spurious harmonic component. Application particularly to phase modulation IQ circuits in radiotelephony.
Claims41
An RF circuit comprising:
- a voltage controlled oscillator delivering an RF signal;
- a phase locked loop to control the voltage controlled oscillator;
- a modulation circuit receiving the RF signal and delivering a modulated signal comprising at least one harmonic component of a frequency equal or proximate to that of the RF signal delivered by the voltage controlled oscillator, the harmonic component being capable of disturbing the operation of the voltage controlled oscillator by injection pulling;
- an injection pulling compensation circuit comprising one input receiving at least the disturbing harmonic component and means for modifying the phase and the amplitude of the harmonic component to deliver an injection pulling compensation signal;
- and
- means for injecting the compensation signal into the voltage controlled oscillator.
A method for stabilising the operation of a voltage controlled oscillator that sends an RF signal and is driven by a phase locked loop comprising:
- receiving through at least one spurious path a harmonic component of a frequency equal or proximate to that of the RF signal sent, capable of disturbing the operation of the voltage controlled oscillator by injection pulling;
- and
- injectioning, into the voltage controlled oscillator, an injection pulling compensation signal, the phase and the amplitude of which are adjusted so as to neutralise the disturbing effects of the harmonic component.
Dependencies are inferred from the claim text.