US5216389A
Expired / Lapsed
US
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Temperature compensation of a crystal reference using direct digital synthesis
Assignee: Motorola Mobility LLC
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Filing: 1992-01-31
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Granted: 1993-06-01
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Expires: 2012-01-31
Abstract
Abstract Certain operational characteristics of a crystal (104) are measured during a testing and grading process. Once determined, information representing these operational characteristics are stored in memory (120) and utilized by a controller (122) to increment a phase increment register (114) upon determining the crystals ambient temperature via a temperature sensing circuit (124). The value stored in the phase increment register (114) is then sent to a phase accumulator (116) where successive phase increments are summed together. This summed value is in turn sent to a sine lookup table (118) where the instantaneous phase value is converted into sine amplitude. Finally, a digital to analog converter (126) converts the amplitude bit stream into an analog signal for use as a reference oscillator frequency having extremely high frequency resolution. The above mentioned process is repeated every clock cycle until a complete sine wave is produced at which point the phase accumulator is reset to zero and the process begins again.
Inventors
- 👤 Cesar W. Carralero
- 👤 Jaime A. Borras
- 👤 Armando J. Gonzalez
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 14:53
CPC Classifications
H; H03; H03L; H03L1/00; H03L1/02; H03L1/022; H03L1/026; H03L7/00; H03L7/06; H03L7/16; H03L7/18; H03L7/1806; G; G06; G06F; G06F1/00; G06F1/02; G06F1/03; G06F1/0321; G06F1/0328
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
103 words
A method for temperature compensating a crystal oscillator circuit which provides a reference signal to a digital synthesizer, the digital synthesizer providing an output signal having a predetermined frequency that is substantially constant over changes in temperature, comprising the steps of: determining the temperature of the crystal oscillator circuit; selecting a phase increment value corresponding to the temperature that has been determined and the predetermined frequency of the output signal; and providing the selected phase increment value to the digital synthesizer in order for the digital synthesizer to use the phase increment value in generating the output signal at substantially the predetermined frequency.
Claim 2
Independent Claim
103 words
A method for temperature compensating a crystal oscillator circuit which provides a reference signal to a digital synthesizer, the digital synthesizer providing an output signal having a predetermined frequency that is substantially constant over changes in temperature, comprising the steps of: determining the temperature of the crystal oscillator circuit; selecting a phase increment value corresponding to the temperature that has been determined and the predetermined frequency of the output signal; and providing the selected phase increment value to the digital synthesizer in order for the digital synthesizer to use the phase increment value in generating the output signal at substantially the predetermined frequency.
Claim 3
Dependent Claim
82 words
The method for temperature compensating the crystal oscillator circuit of claim 1, comprising the further steps of: characterizing the crystal oscillator circuit over temperature in order to determine the crystal oscillator's change in reference signal frequency over a given temperature range; calculating phase increment values for generating the output signal at different temperatures in the temperature range given the crystal oscillator circuit's change in reference signal frequency over the given temperature range; and storing the phase increment values in a storage means.
Claim 4
Dependent Claim
51 words
The method for temperature compensating a crystal oscillator circuit of claim 2, wherein the step of selecting the phase increment value comprises comparing the determined temperature of the crystal oscillator to the phase increment values stored in the storage means and selecting the phase increment value corresponding to the determined temperature.
Claim 5
Dependent Claim
91 words
A temperature compensated circuit, comprising: a reference oscillator circuit for generating a reference oscillator signal; a synthesizer means for receiving the reference oscillator signal and for providing an output signal having a predetermined frequency; and a compensation means for determining the temperature of the reference oscillator circuit and for providing phase increment values to the synthesizer means in order for the synthesizer means to generate the output signal, the phase increment values are related to both the predetermined frequency of the output signal and the temperature of the reference oscillator circuit.
Claim 6
Dependent Claim
91 words
A temperature compensated circuit, comprising: a reference oscillator circuit for generating a reference oscillator signal; a synthesizer means for receiving the reference oscillator signal and for providing an output signal having a predetermined frequency; and a compensation means for determining the temperature of the reference oscillator circuit and for providing phase increment values to the synthesizer means in order for the synthesizer means to generate the output signal, the phase increment values are related to both the predetermined frequency of the output signal and the temperature of the reference oscillator circuit.
Claim 7
Dependent Claim
27 words
The temperature compensated circuit of claim 4, wherein the reference oscillator circuit comprises a crystal element having a predetermined resonant frequency range over a predetermined temperature range.
Claim 8
Dependent Claim
78 words
The temperature compensated circuit of claim 5, wherein the compensation means comprises: a storage means for storing the phase increment values corresponding to said predetermined resonant frequency range; a temperature sensing means for sensing the operating temperature of the crystal element and providing a corresponding temperature signal; and a control means coupled to the temperature sensing means for providing a phase increment value to the synthesizer means corresponding to the temperature signal received from the temperature sensing means.
Claim 9
Dependent Claim
101 words
A circuit for providing a temperature compensated output signal, comprising: a resonant circuit having a predetermined resonant frequency range over a predetermined temperature range, the resonant circuit providing a reference signal having a frequency that varies over the predetermined temperature range; a temperature sensing means for determining the temperature of the resonant circuit; a control means coupled to the temperature sensing means for providing a phase increment value related to the temperature of the resonant circuit; and a digital synthesizer means responsive to the reference signal and to the phase increment value for generating an output signal having a predetermined frequency.
Claim 10
Dependent Claim
101 words
A circuit for providing a temperature compensated output signal, comprising: a resonant circuit having a predetermined resonant frequency range over a predetermined temperature range, the resonant circuit providing a reference signal having a frequency that varies over the predetermined temperature range; a temperature sensing means for determining the temperature of the resonant circuit; a control means coupled to the temperature sensing means for providing a phase increment value related to the temperature of the resonant circuit; and a digital synthesizer means responsive to the reference signal and to the phase increment value for generating an output signal having a predetermined frequency.
Claim 11
Dependent Claim
13 words
The circuit of claim 7, wherein the resonant circuit comprises a crystal element.
Claim 12
Dependent Claim
25 words
The circuit of claim 7, wherein the digital synthesizer means comprises a phase increment means for storing the phase increment values from the control means.
Claim 13
Dependent Claim
54 words
The circuit of claim 9, wherein a new phase increment value is loaded into the phase increment means for each frequency cycle of the resonant circuit and the previous phase increment value stored in the phase increment means is sent to a phase accumulator means for accumulating the sum of successive phase increment values.
Claim 14
Dependent Claim
117 words
A synthesizer, comprising: a temperature compensated circuit, comprising: a reference oscillator circuit for generating a reference oscillator signal; a digital synthesizer means for receiving the reference oscillator signal and providing an output signal having a predetermined frequency; and a compensation means for determining the temperature of the reference oscillator circuit and for providing phase increment values which are related to both the temperature of the reference oscillator circuit and the frequency of the output signal to the digital synthesizer means in order for the digital synthesizer means to generate the output signal substantially at the predetermined frequency; and a phase locked loop synthesizer section responsive to the output signal for providing a phase locked loop output signal.
Claim 15
Dependent Claim
117 words
A synthesizer, comprising: a temperature compensated circuit, comprising: a reference oscillator circuit for generating a reference oscillator signal; a digital synthesizer means for receiving the reference oscillator signal and providing an output signal having a predetermined frequency; and a compensation means for determining the temperature of the reference oscillator circuit and for providing phase increment values which are related to both the temperature of the reference oscillator circuit and the frequency of the output signal to the digital synthesizer means in order for the digital synthesizer means to generate the output signal substantially at the predetermined frequency; and a phase locked loop synthesizer section responsive to the output signal for providing a phase locked loop output signal.
Claim 16
Dependent Claim
25 words
The synthesizer of claim 11, wherein the reference oscillator circuit comprises a crystal element having a predetermined resonant frequency range over a predetermined temperature range.
Claim 17
Dependent Claim
76 words
The synthesizer of claim 12, wherein the compensation means comprises: a storage means for permanently storing phase increment values corresponding to said predetermined resonant frequency range; a temperature sensing means for sensing the operating temperature of the crystal element and providing a corresponding temperature signal to a control means; and said control means coupled to the temperature sensing means for providing a phase increment value to the digital synthesizer means corresponding to the temperature signal received.
Claim 18
Dependent Claim
112 words
A radio, comprising: a receiver; and a synthesizer circuit, comprising: a temperature compensated circuit, comprising: a reference oscillator circuit for generating a reference oscillator signal; a digital synthesizer means for receiving the reference oscillator signal and providing an output signal having a predetermined frequency; and a compensation means for determining the temperature of the reference oscillator circuit and for providing phase increment values which are related to both the temperature of the reference oscillator circuit and the frequency of the output signal to the digital synthesizer means in order for the digital synthesizer means to generate the output signal substantially at the predetermined frequency, the receiver being responsive to the output signal.
Claim 19
Dependent Claim
112 words
A radio, comprising: a receiver; and a synthesizer circuit, comprising: a temperature compensated circuit, comprising: a reference oscillator circuit for generating a reference oscillator signal; a digital synthesizer means for receiving the reference oscillator signal and providing an output signal having a predetermined frequency; and a compensation means for determining the temperature of the reference oscillator circuit and for providing phase increment values which are related to both the temperature of the reference oscillator circuit and the frequency of the output signal to the digital synthesizer means in order for the digital synthesizer means to generate the output signal substantially at the predetermined frequency, the receiver being responsive to the output signal.
Claim 20
Dependent Claim
14 words
The radio of claim 14, wherein the reference oscillator circuit comprises a crystal element.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-05-31 | 1996-11-30 | 1997-06-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-05-31 | 2000-11-30 | 2001-06-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-05-31 | 2004-11-30 | 2005-06-01 | $7700.00 | Window Closed / Lapsed |