Programmable capacitances for PLL loop and power supply noise filters
OwnerBrian Amick, Claude Gauthierinventors
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Abstract
A phase locked loop having a programmable capacitance stage is provided. The programmable capacitance stage facilitates a selective post-silicon adjustment of capacitance amounts between a PLL loop filter capacitance and a power supply noise filter capacitance, thereby allowing a designer to reduce capacitance area space wastage and to obtain an optimal PLL performance level.
Claims19
An integrated circuit, comprising:
- a voltage controlled oscillator arranged to receive power from a power supply and responsive to a first signal applied at a first input thereof;
- and
- a programmable capacitance stage comprising a first capacitance disposed between the power supply and the first input and a second capacitance disposed between the power supply and ground,
- wherein the first capacitance and the second capacitance are selectively adjustable.
A phase locked loop adapted to connect to a power supply and ground, comprising:
- a phase detector stage responsive to an input signal;
- a charge pump stage responsive to the phase detector stage, wherein the charge pump stage outputs a bias signal;
- a voltage controlled oscillator responsive to the bias signal;
- and
- a programmable capacitance stage that is selectively controlled to adjust a first capacitance between the power supply and ground and a second capacitance between the power supply and the bias signal.
An integrated circuit, comprising:
- oscillator means for controlling a frequency, wherein the oscillator means is responsive to a bias signal;
- and
- programmable capacitance means for selectively adjusting a first capacitance disposed between a power supply and the bias signal and a second capacitance disposed between the power supply and ground.
A method for post-silicon adjustment of a phase locked loop, comprising:
- selectively positioning a first capacitance amount between a power supply and a bias signal of the phase locked loop, wherein the selective positioning of the first capacitance amount occurs by control of at least one switching device;
- selectively positioning a second capacitance amount between the power supply and ground;
- and
- operating the phase locked loop such that the first capacitance amount serves as a loop filter capacitance and the second capacitance amount serves as a power supply noise filter capacitance.
A method for optimizing a phase locked loop, comprising:
- forming an integrated circuit comprising:
- a voltage controlled oscillator arranged to receive power from a power supply and responsive to a first signal applied at a first input thereof;
- and
- a programmable capacitance stage comprising a first capacitance disposed between the power supply and the first input and a second capacitance disposed between the power supply and ground;
- and
- adjusting the first capacitance and the second capacitance to optimize the phase locked loop.
Dependencies are inferred from the claim text.