Systems and methods for digital synthesis of output signals using resonators
Systems and methods for digital synthesis of an output signal using a frequency generated from a resonator and computing amplitude values that take into account temperature variations and resonant frequency variations resulting from manufacturing variability are described. A direct frequency synthesizer architecture is leveraged on a high Q resonator, such as a film bulk acoustic resonator (FBAR), a spectral multiband resonator (SMR), and a contour mode resonator (CMR) and is used to generate pristine signals.
1. A direct frequency synthesizer comprising:
a high speed resonator that generates a frequency signal;
an oscillator that receives the frequency signal and generates an output signal;
a clock generator that receives the output signal of the oscillator and generates a clock signal from the output signal;
a controller that generates a frequency control word describing a desired output digital signal; and
a direct digital frequency synthesizer that receives the clock signal and the frequency control word and generates the desired output digital signal based on the clock signal and the frequency control word and;
a direct RF transmitter that receives the clock signal and a digital base-band signal and generates the desired output digital signal based on the base-band signal and a desired output frequency;
a high speed digital to analog converter that receives the output signal from the oscillator and the desired output digital signal from at least one of the direct digital frequency synthesizer and the direct RF transmitter and outputs an analog signal based on the desired output digital signal.
2. The direct frequency synthesizer of claim 1 further comprising:
frequency compensation circuitry that generates a frequency compensation value to adjust for errors in the frequency signal generated by the high speed resonator and adds the frequency compensation value to the frequency control word.
3. The direct frequency synthesizer of claim 2 wherein the frequency compensation circuitry comprises:
a temperature sensor that measure an operating temperature; and
wherein the frequency compensation circuitry uses the operating temperature to calculate a correct amplitude value for particular time period to adjust the frequency compensation value.
4. The direct frequency synthesizer of claim 2 wherein the frequency compensation circuitry comprises:
frequency offset correction circuitry that accounts for resonant frequency offsets in the frequency signal generated by the high speed resonator due to properties of the resonator and provides frequency offset information to the frequency compensation circuitry to generate the frequency compensation value.
5. The direct frequency synthesizer of claim 2 wherein the frequency compensation circuitry comprises a non-volatile memory that stores different output signals that may be generated using the direct digital synthesizer that is used in generating the frequency compensation value.
6. The direct frequency synthesizer of claim 5 , wherein the non-volatile memory outputs an initial frequency error, process information, and a preset frequency to the frequency compensation circuitry.
7. The direct frequency synthesizer of claim 2 wherein the frequency compensation frequency circuitry comprises:
an analog to digital converter that receives the clock signal from the clock generator and a voltage controlled oscillator signal and generates a frequency adjustment value based on the voltage control oscillator signal, wherein the frequency adjustment value is used to generate the frequency compensation value.
8. The direct frequency synthesizer of claim 1 wherein the high speed resonator is a resonator selected from the group consisting of a bulk acoustic wave (BAW) resonator, a film bulk acoustic resonator (FBAR), a spectral multiband resonator (SMR), and a contour mode resonator (CMR).
9. A method for generating a signal from a high speed resonator comprising:
generating a frequency signal using a high speed resonator receiving the frequency signal in an oscillator;
generating an output signal from the frequency signal using the oscillator;
receiving the output signal of the oscillator in a clock generator;
generating a clock signal from the output signal of the oscillator using the clock generator;
generating a frequency control word describing a desired output digital signal using a controller;
receiving the clock signal and the frequency control word in a direct digital frequency synthesizer; and
generating the desired output digital signal based on the clock signal and frequency control word using the direct digital frequency synthesizer;
receiving the clock signal and a digital base-band signal in a direct RF transmitter; and
generating the desired output digital signal based on the base-band signal and a desired output frequency;
receiving at a high speed digital to analog converter the output signal from the oscillator and the desired output digital signal from at least one of the direct digital frequency synthesizer and the direct RF transmitter; and
outputting at the high speed digital to analog converter an analog signal based on the desired output digital signal.
10. The method of claim 9 further comprising:
generating a frequency compensation value to adjust for errors in the frequency signal generated by the high speed resonator using frequency compensation circuitry; and
adding the frequency compensation value to the frequency control word.
11. The method of claim 10 further comprising:
measuring an operating temperature using a temperature sensor; and
calculating a correct amplitude value for particular time period based on the operating temperature to adjust the frequency compensation value using the frequency compensation circuitry.
12. The method of claim 10 wherein the frequency compensation circuitry comprises:
accounting for resonant frequency offsets in the frequency signal generated by the high speed resonator due to properties of the resonator and providing frequency offset information representing the resonant frequency offsets to the frequency compensation circuitry to generate the frequency compensation value.
13. The method of claim 10 further comprising storing different output signals that may be generated using the direct digital synthesizer in the nonvolatile memory for use in generating the frequency compensation value.
14. The method of claim 10 further comprising outputting an initial frequency error, process information, and a preset frequency to the frequency compensation circuitry from the non-volatile memory.
15. The method of claim 10 further comprising:
receiving the clock signal from the clock generator and a voltage controlled oscillator signal in an analog to digital converter; and
generating a frequency adjustment value based on the voltage control oscillator signal using the analog to digital converter wherein the frequency adjustment value is used to generate the frequency compensation value.
16. The method of claim 9 wherein the high speed resonator is a resonator selected from the group consisting of a bulk acoustic wave (BAW) resonator, a film bulk acoustic resonator (FBAR), a spectral multiband resonator (SMR), and a contour mode resonator (CMR).