Integrated frequency calibration architecture
AssigneeViaSat, Inc.
InventorDavid R Saunders
Life of this patent
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Abstract
In an exemplary embodiment, a free running VCO has two modes: a normal operating mode and a calibration mode. In the calibration mode, the free running VCO is phase lock looped with itself instead of a calibration VCO. Furthermore, in an exemplary embodiment, a tuning voltage for the free running VCO is adjusted to offset any tuning error. In addition, in various embodiments a reference crystal oscillator used in the phase lock loop is located on a DSP module instead of on the RF module. In yet another exemplary embodiment, the free running VCO is the only high frequency VCO on a radio frequency module.
Claims20
An integrated frequency calibration architecture comprising:
- a radio frequency (RF) module in communication with a digital signal processor (DSP) module, wherein the RF module is located on an integrated circuit;
- a voltage controlled oscillator (VCO) on the RF module, wherein the VCO is configured to have a normal operation mode and a frequency calibration mode;
- a phase lock loop (PLL) on the RF module, wherein the PLL provides a VCO input voltage to the VCO based on a scaled reference frequency during the frequency calibration mode;
- a VCO tuning circuit comprising a digital-to-analog converter (DAC), wherein the DAC adjusts to the VCO input voltage during the frequency calibration mode, and wherein the DAC connects to the VCO during the normal operation mode;
- and
- a switch configured to switch the VCO between the normal operation mode and the frequency calibration mode.
A method of frequency calibration of a voltage controlled oscillator (VCO) on an integrated circuit, the method comprising:
- phase locking, on the integrated circuit, the VCO based on a reference frequency and a VCO output frequency and generating a VCO input voltage;
- and
- adjusting an output voltage of a digital-to-analog converter (DAC) to match the VCO input voltage during a frequency calibration mode and to generate an adjusted DAC output voltage;
- wherein the adjusted DAC output voltage provides the VCO input voltage during a normal operating mode.
A method of frequency calibration of a voltage controlled oscillator (VCO), the method comprising:
- phase locking the VCO based on a reference frequency and a VCO output frequency and generating a VCO input voltage;
- and
- adjusting an output voltage of a digital-to-analog converter (DAC) to match the VCO input voltage during a frequency calibration mode and to generate an adjusted DAC output voltage;
- wherein the adjusted DAC output voltage provides the VCO input voltage during a normal operating mode;
- comparing the adjusted DAC output voltage and the VCO input voltage during the normal operating mode to measure a comparator offset voltage error;
- and
- re-adjusting the output voltage of the DAC to match a combination of the VCO input voltage and the comparator offset voltage error to re-generate the adjusted DAC output voltage.
Dependencies are inferred from the claim text.