Phase-locked loop with an adjustable output divider
AssigneeXilinx, Inc.
InventorMohamed N. Elzeftawi
Life of this patent
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Abstract
An apparatus relates generally to providing a divided signal output. In such an apparatus, a controller is coupled to receive a reference frequency count and a feedback frequency count to determine a difference therebetween to provide a control setting. A divider is coupled to receive the control setting to provide the divided signal output. The divider includes an adjustable load impedance. The control setting is coupled to adjust the load impedance of the divider to adjust a self-resonance frequency of the divider.
Claims20
An apparatus for providing a divided signal output, comprising:
- a controller configured to receive a reference frequency count and a feedback frequency count and configured to determine a difference between the reference frequency count and the feedback frequency count to provide as a control setting;
- an output divider (“divider”) configured to receive the control setting and to divide the control setting to provide the divided signal output;
- wherein the divider includes an adjustable load impedance;
- and
- wherein the divider is configured to adjust load impedance of the divider responsive to the control setting to adjust a self-resonance frequency of the divider.
A method for tuning an adjustable divider, comprising:
- initiating a calibration mode to cause the adjustable divider to self-resonate to obtain a feedback count;
- determining a difference between a reference count and the feedback count to produce an error vector;
- obtaining a control setting using the error vector;
- and
- adjusting impedance of the adjustable divider with the control setting.
A method for adjusting an operating range in an integrated circuit die, comprising:
- disabling an output of a voltage controlled oscillator of a first phase-locked loop;
- sweeping codes of a first adjustable IQ divider of the first phase-locked loop;
- obtaining self-resonance frequencies as outputs of the first adjustable IQ divider corresponding to the codes swept;
- populating a table with the codes swept having pointers respectively thereto;
- wherein the pointers are respectively associated with the self-resonance frequencies;
- and
- selecting a code of the codes swept for a predetermined operating frequency to adjust a second adjustable IQ divider in a second phase-locked loop in the integrated circuit die.
Dependencies are inferred from the claim text.