Method and apparatus for reducing the start time of a VCXO
AssigneeSony Ericsson Mobile Communications AB
InventorBruce Wilcox
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Abstract
A voltage controlled oscillator, such as a VCXO (Voltage Controlled Crystal Oscillator), for generating a desired reference frequency in a wireless terminal with a reduced start-up time is described herein. According to the present invention, the VCXO comprises an oscillator that generates the desired reference frequency based on a variable voltage applied to the oscillator by a voltage controller. In addition, the VCXO includes a start-up controller that applies a bias voltage to an oscillator input node to reduce a capacitance associated with the oscillator, and therefore, to reduce the start-up time without negatively impacting the DC current consumption or the tuning range of the VCXO.
Claims44
A voltage controlled oscillator in a wireless terminal comprising:
- an oscillator to generate a reference frequency based on a variable voltage applied to an input node of the oscillator;
- and
- a start-up controller operatively connected to the oscillator to apply a temporary bias voltage to the oscillator input node to reduce a start-up time of the voltage controlled oscillator by reducing a capacitance associated with the oscillator.
A method of operating a voltage controlled oscillator in a wireless terminal comprising:
- sensing that the voltage controlled oscillator is powered on;
- applying a temporary bias voltage to an oscillator input node to reduce a start-up time associated with the voltage controlled oscillator by reducing an initial capacitance associated with the oscillator input node;
- and
- removing the temporary bias voltage from the oscillator input node responsive to the voltage controlled oscillator meeting a predetermined operating condition.
A method of reducing a start-up time associated with an oscillator circuit comprising:
- detecting that the oscillator circuit has been powered on by sensing the presence of an oscillator output voltage;
- and
- applying a temporary bias voltage to the oscillator circuit to reduce a start-up time associated with the oscillator circuit by reducing a capacitance of the oscillator circuit.
A start-up controller for reducing a start-up time associated with an oscillator circuit, the start-up controller comprising:
- a detector circuit to generate a control signal upon sensing the presence of an oscillator output voltage;
- and
- a fast start network to apply a temporary bias voltage to an input node of the oscillator circuit in response to the detector control signal to reduce a start-up time associated with the oscillator circuit by reducing a capacitance associated with the oscillator input node.
Dependencies are inferred from the claim text.