IPC분류정보
국가/구분 |
United States(US) Patent
등록
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국제특허분류(IPC7판) |
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출원번호 |
US-0358563
(2003-02-05)
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발명자
/ 주소 |
- Welland, David R.
- Wang, Caiyi
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출원인 / 주소 |
- Silicon Laboratories, Inc.
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대리인 / 주소 |
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인용정보 |
피인용 횟수 :
4 인용 특허 :
83 |
초록
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A method and apparatus for synthesizing high-frequency signals, such as wireless communication signals, includes a phase-locked loop (PLL) frequency synthesizer with a variable capacitance voltage controlled oscillator (VCO) that has a discretely variable capacitance in conjunction with a continuous
A method and apparatus for synthesizing high-frequency signals, such as wireless communication signals, includes a phase-locked loop (PLL) frequency synthesizer with a variable capacitance voltage controlled oscillator (VCO) that has a discretely variable capacitance in conjunction with a continuously variable capacitance. The discretely variable capacitance may provide coarse tuning adjustment of the variable capacitance to compensate for capacitor and inductor tolerances and to adjust the output frequency to be near the desired frequency output. The continuously variable capacitance may provide a fine tuning adjustment of the variable capacitance to focus the output frequency to match precisely the desired frequency output. During fine tuning adjustment, the PLL may be controlled by a plurality of analog control signals. The analog control signals may be derived by first generating a plurality of phase shifted signals from a divided version of the VCO output clock. Second, the phase differences between the plurality of phase shifted signals and a divided version of a reference clock may be detected and then converted to the analog control signals.
대표청구항
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1. Controllable oscillator circuitry configured to have an output frequency dependent upon a capacitance amount within an LC tank resonant structure, comprising:a plurality of non-varactor diode variable capacitance circuits that together provide at least part of the capacitance amount, each variabl
1. Controllable oscillator circuitry configured to have an output frequency dependent upon a capacitance amount within an LC tank resonant structure, comprising:a plurality of non-varactor diode variable capacitance circuits that together provide at least part of the capacitance amount, each variable capacitance circuit having at least one control node configured to receive an analog control signal that determines at least in part an amount of capacitance contributed by the circuit to the capacitance amount; and a plurality of different analog signals coupled to provide the analog control signals for the variable capacitance circuits, the different analog signals being adjusted based upon a phase difference between a first signal that is related to the output frequency and a second signal. 2. The controllable oscillator circuitry of claim 1, wherein the plurality of different analog signals are configured to provide to the control nodes a continuously variable signal level between a first signal level and a second signal level.3. The controllable oscillator circuitry of claim 2, wherein at least two of the plurality of different analog signals concurrently provide to the control nodes at any given time signal levels between the first signal level and the second signal level.4. The controllable oscillator circuitry of claim 3, wherein at least one of the plurality of different analog signals is additionally providing to the control nodes at any given time the first signal level or the second signal level.5. The controllable oscillator circuitry of claim 2, further comprising converter circuitry having an output comprising the plurality of different analog signals and having an input comprising at least one signal indicative of the phase difference.6. The controllable oscillator circuitry of claim 5, wherein the converter circuitry has an input comprising a single master signal indicative of the phase difference.7. The controllable oscillator circuitry of claim 6, wherein the master signal comprises a voltage signal having a voltage level that varies with the phase difference.8. The controllable oscillator circuitry of claim 6, wherein the plurality of different analog signals comprises a plurality of voltage signals.9. The controllable oscillator circuitry of claim 8, wherein at least a portion of the plurality of voltage signals differ from each other by an incremental voltage amount.10. The controllable oscillator circuitry of claim 6, further comprising phase detection circuitry having an input comprising at least one signal relating to the output frequency and at least one additional signal and having an output comprising at least one signal indicative of the phase difference.11. The controllable oscillator circuitry of claim 7, wherein the second signal relates to a reference frequency and wherein the input to the phase detection circuitry comprises a plurality of phase shifted signals relating to the output frequency and a single signal relating to the reference frequency, and wherein the output of the phase detection circuitry comprises a plurality of voltage signals indicative of the phase differences between the plurality of phase shifted signals relating to the output frequency and the single signal relating to the reference frequency, and wherein the converter circuitry comprises a plurality of sample and hold circuits having an output comprising the plurality of different analog signals and having an input comprising the plurality of voltage signals indicative of the phase differences between the plurality of phase shifted signals relating to the output frequency and the single signal relating to the reference frequency.12. The controllable oscillator circuitry of claim 2, wherein the controllable oscillator comprises a differential controllable oscillator including a differential amplifier and wherein the plurality of variable capacitance circuits comprise a first set of positive side variable capacitance circuits and a second set of corresponding negative side variable capacitance circuits, the control node for each positive side variable capacitance circuit being coupled to a control node for the corresponding negative side variable capacitance circuit.13. The controllable oscillator circuitry of claim 2, wherein the plurality of variable capacitance circuits are integrated in the same integrated circuit.14. The controllable oscillator of claim 13, further comprising an external inductor coupled to the integrated circuit to form an LC tank resonant structure.15. The controllable oscillator circuitry of claim 1, further comprising a plurality of discretely variable capacitance circuits that together provide at least part of the capacitance amount for the controllable oscillator and a plurality of different digital signals coupled to the discretely variable capacitance circuits, the different digital signals being adjusted based upon a difference between a first signal that is related to the output frequency and a second signal that is related to a reference frequency.16. The controllable oscillator circuitry of claim 15, wherein the plurality of different digital signals are first adjusted to provide a coarse tuning of the output frequency and the plurality of different analog signals are then adjusted to provide a fine tuning of the output frequency.17. The controllable oscillator circuitry of claim 2, further comprising a master signal generated utilizing the first and second signals, wherein the master signal is indicative of the phase difference between the first and second signals and wherein the master signal is used to generate the plurality of different analog signals.18. The controllable oscillator circuitiy of claim 17, wherein the master signal has a voltage level which varies with the phase difference between the first and second signals.19. The controllable oscillator circuitry of claim 2, wherein the variable capacitance circuits comprise capacitance circuits being configured to be continuously variable between at least two capacitance amounts.20. The controllable oscillator circuitry of claim 19, wherein the capacitance circuits comprise capacitor circuits that each include at least one capacitor and at least one variable resistance element having a control node, each control node of the variable resistance elements concurrently receiving at least one of the different analog control signals to determine the capacitance amount contributed by the capacitance circuit to the combined capacitance amount and thereby to adjust the output frequency.21. The controllable oscillator circuitry of claim 20, wherein each of the capacitor circuits comprises at least a first capacitor coupled between a first node and a second node, a second capacitor coupled between the second node and a third node, and a variable resistance element coupled between the second node and the third node.22. The controllable oscillator circuitry of claim 2, wherein the plurality of variable capacitance circuits comprise at least five variable capacitance circuits.23. A method for controlling a controllable oscillator configured to have an output frequency dependent upon a capacitance amount within an LC tank resonant structure, comprising:providing a plurality of non-varactor diode variable capacitance circuits that together provide at least part of the capacitance amount, each variable capacitance circuit having at least one control node configured to receive an analog control signal that determines at least in part an amount of capacitance contributed by that circuit to the capacitance amount; generating a plurality of different analog signals coupled to provide the control signals for the variable capacitance circuits; and controlling the output frequency of the controllable oscillator, at least in part, by adjusting the different analog signals based upon a phase difference between a first signal that is related to the output frequency and a second signal. 24. The method of claim 23, further comprising configuring the plurality of different analog signals to provide signal levels that are continuously variable between a first signal level and a second signal level.25. The method of claim 24, further comprising concurrently providing to the control nodes at any given time at least two of the plurality of different analog signals at signal levels between the first signal level and the second signal level.26. The method of claim 25, further comprising additionally providing to the control nodes any given time at least one of the plurality of different analog signals at the high signal level or the low signal level.27. The method of claim 24, wherein the generating step comprises generating the plurality of different analog signals based upon at least one signal indicative of the phase difference.28. The method of claim 27, wherein the generating step comprises utilizing a single master signal indicative of the phase difference to generate the plurality of different analog signals.29. The method of claim 28, wherein the master signal comprises a voltage signal having a voltage level that varies with the phase difference.30. The method of claim 28, wherein the plurality of different analog signals comprises a plurality of voltage signals.31. The method of claim 24, further comprising providing a plurality of discretely variable capacitance circuits that together provide at least part of the capacitance amount for the controllable oscillator, generating a plurality of different digital signals coupled to the discretely variable capacitance circuits, and adjusting the different digital signals based upon a phase difference between a first signal that is related to the output frequency and a second signal that is related to a reference frequency.32. The method of claim 31, further comprising first adjusting the plurality of different digital signals to provide a coarse tuning of the output frequency and then adjusting the plurality of different analog signals to provide a fine tuning of the output frequency.33. The method of claim 24, generating a master signal utilizing the first and second signals and generating the plurality of different analog signals utilizing the master signal, the master signal being indicative of the phase difference between the first and second signals.34. The method of claim 24, wherein the variable capacitance circuits comprise capacitance circuits being configured to be continuously variable between at least two capacitance amounts.35. The method of claim 34, wherein the capacitance circuits comprise capacitor circuits that include at least one capacitor and at least one variable resistance element having a control node, each control node of the variable resistance elements concurrently receiving at least one of the different analog control signals to determine the capacitance amount contributed by the capacitance circuit to the combined capacitance amount and thereby to adjust the output frequency.36. The method of claim 35, wherein each of the capacitor circuits comprises at least a first capacitor coupled between a first node and a second node, a second capacitor coupled between the second node and a third node, and a variable resistance element coupled between the second node and the third node.37. The method of claim 24, wherein the plurality of variable capacitance circuits comprise at least five variable capacitance circuits.38. The method of claim 24, wherein the plurality of variable capacitance circuits are integrated in the same integrated circuit.39. The method of claim 38, further comprising providing an external inductor coupled to the integrated circuit to form an LC tank resonant structure.
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