Oscillator amplitude calibration
AssigneeCadence Design Systems, Inc.
InventorsMohammadamin Karami, Navid Yaghini, Hemesh Yasotharan
Life of this patent
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Abstract
Multiple voltage amplitudes for an oscillator in a phase-locked loop may be selected to meet various design goals/criteria (e.g., frequency range of operation, jitter, power consumption, etc.). These multiple voltage amplitudes may be stored in a lookup table memory that relates frequency ranges to reference voltages. A reference voltage for a particular oscillator may then be selected and generated. A feedback loop may compare the amplitude output by the oscillator to the reference voltage and adjusts a bias current of the oscillator with the goal of substantially equalizing the oscillator output to the reference voltage.
Claims18
An integrated circuit, comprising:
- an inductor-capacitor (LC) tank oscillator having an output signal and a bias current control input;
- and
- feedback circuitry to, based on a reference voltage indicator received from a lookup table, adjust the bias current control input to minimize a difference between a reference voltage based on the reference voltage indicator and an indicator of the magnitude of the output signal, wherein the reference voltage is generated by a digital-to-analog converter that receives the reference voltage indicator.
A method, comprising:
- receiving, from a memory on an integrated circuit, a first target amplitude value;
- generating a first reference voltage based on the first target amplitude value;
- producing a first output amplitude indicator voltage from a first output signal of a first inductor-capacitor (LC) tank oscillator;
- adjusting a first current bias of the first LC tank oscillator based on a first comparison of the first reference voltage and the first output amplitude indicator voltage;
- and
- receiving, from the memory on the integrated circuit, a second target amplitude value that is not equal to the first target amplitude value;
- generating a second reference voltage based on the second target amplitude value;
- producing a second output amplitude indicator voltage from a second output signal of a second inductor-capacitor (LC) tank oscillator;
- and
- adjusting a second current bias of the second LC tank oscillator based on a second comparison of the second reference voltage and the second output amplitude indicator voltage.
An integrated circuit, comprising:
- a memory to provide a first reference voltage indicator;
- and a first phase-locked loop comprising:
- an inductor-capacitor (LC) tank oscillator having an output signal and a bias current control input;
- and feedback circuitry to, based on the first reference voltage indicator received from the memory, adjust a bias current control input signal to minimize a difference between a reference voltage based on the first reference voltage indicator and an indicator of the magnitude of the output signal.
Dependencies are inferred from the claim text.