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US 2009/0021311 A1Published application
VCO Pre-Compensation
AssigneeInfineon Technologies AG
InventorsChristian Grewing, Stefan Heinrich van Waasen, Emericks Anders
Life of this patent
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Abstract
A VCO device is described that has pre-compensation. Digitally switchable compensation capacitors are selectively activated to adjust operation of the VCO to mitigate undesirable operational effects. In some example embodiments, the digitally switchable compensation capacitors of the VCO are adjusted to compensate for the effects of activating (from a quiescent state) an output buffer driven by the VCO.
Claims20
A frequency synthesizer, comprising:
- an oscillator comprising a programmable tuning circuit;
- an output buffer for buffering an output of the oscillator, wherein the output buffer is selectively activated and deactivated in response to a signal for controlling the output buffer;
- and
- a tuning control circuit that is configured to program the tuning circuit in response to an OUTPUT BUFFER ON condition.
1 more element
A frequency synthesizer, comprising:
- an output buffer circuit that is selectively activated and deactivated in response to a signal for controlling the output buffer;
- and
- an oscillator circuit comprising:
- a cross-coupled transistor pair including a first transistor and a second transistor, each transistor having a drain and a gate, wherein a gate of each transistor is coupled to the drain of the other transistor, wherein at least one drain is coupled to an input of the output buffer;
- a first tuning circuit that is coupled between the source of the first transistor and the source of the second transistor and that comprises an LC-circuit that is controlled by a switched capacitor bank that is configured to change from a first capacitance to a second capacitance in response to the output buffer being activated by the output buffer control signal;
- and
- a second tuning circuit that is coupled between the source of the first transistor and the source of the second transistor and that comprises a control terminal that is coupled to the output of a phase-lock loop (PLL) that is coupled between the source of the first transistor and the source of the second transistor.
4 more elements
A method, comprising:
- applying power to a voltage controlled oscillator (VCO) that comprises a programmable tuning circuit for establishing an oscillation frequency of the VCO;
- applying power to an output buffer that has an input that is coupled to an output of the VCO, whereby the applying power to the output buffer causes transient effects on the oscillation frequency of the VCO;
- programming the programmable tuning circuit with a first set of parameters in response to a decision to apply power to the VCO;
- programming the programmable tuning circuit with a second set of parameters in response to a decision to apply power to the output buffer.
1 more element
Dependencies are inferred from the claim text.