Device and method for compensating for a resonator
AssigneeCsem Centre Suisse D'Electronique Et De Microtechnique SA—Recherche Et DéVeloppement
InventorDavid Ruffieux
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Abstract
A device for compensating for the frequency of a resonator includes (a) a temperature sensor, (b) a sequencer determining a second compensation signal on the basis of the temperature and corresponding to a positive value N, and a third compensation signal on the basis of the temperature corresponding to a ratio between a positive integer S and N, S being lower than or equal to N, and (c) a variable counter receiving the compensation signals and generating a fourth output signal every N periods of a clock signal from the resonator and generating a fifth signal for modifying the charge capacity of the resonator.
Claims14
A device capable of compensating for the manufacturing tolerances and the temperature drift of a reference frequency of a silicon-type resonator, generating a programmable compensated reference frequency Fref, comprising:
- a temperature sensor capable of measuring an operating temperature of said resonator and capable of providing a first signal corresponding to the temperature,
- a sequencer connected to said temperature sensor, said sequencer being capable of determining a second compensation signal, from the first signal and as a function of said temperature value, using calibration data intended to be stored in a storage means connected to said sequencer, said second signal corresponding to a positive value N, said sequencer being, moreover, capable of determining a third compensation signal, from said first signal and as a function of the temperature value, using calibration data, said third signal corresponding to a ratio between a positive integer S and N, S being less than or equal to N,
- a variable counter connected to said sequencer and connected to an oscillator provided with said resonator, said variable counter—being capable of receiving said compensation signals, capable of producing a fourth output signal every N periods of a clock signal coming from said resonator, and capable of detecting the state S, arranged to produce a fifth signal capable of modifying the load capacity of said oscillator,
- wherein N comprises an integer part Nint and a fractional part Nfrac, and in that the variable counter comprises:
- an accumulator connected to the outlet of the sequencer and capable of receiving a sixth signal corresponding to the fractional part of N,
- a Nint, Nint+1 dual-module counter connected to the outlet of the accumulator and to the outlet of the sequencer, capable of receiving a seventh signal corresponding to the integer part of N, and whereof the output is the compensated reference frequency Fref,
- a counting element connected to the outlet of the sequencer and to the outlet of the dual-module counter, capable of receiving said third signal and said fourth signal, said counting element being capable of producing the fifth signal as a function of the state S.
A method for compensating for manufacturing tolerances and for the temperature drift of a reference frequency of a silicon-type piezoelectric resonator comprising the following steps:
- turning on of a temperature sensor by a sequencer connected to said sensor,
- reading a first signal corresponding to an operating temperature measurement of said resonator, said first signal coming from the temperature sensor,
- determination by the sequencer of a second compensation signal from said first signal using calibration data intended to be stored in a storage means connected to said sequencer, the second signal corresponding to a positive value N, N comprising an integer part Nint and a fractional part Nfrac,
- determination by the sequencer of a third compensation signal from said first signal using calibration data, the third signal corresponding to a ratio between a positive integer S and N, S being less than or equal to N,
- reception of the compensated signals by a variable counter connected to the sequencer and to an oscillator provided with said resonator, the variable counter comprising:
- an accumulator connected to the output of the sequencer and capable of receiving a sixth signal corresponding to the fractional part of N,
- a Nint, Nint+1 dual-module counter connected to the outlet of the accumulator and to the outlet of the sequencer, capable of receiving a seventh signal corresponding to the integer part of N,
- a counting element connected to the outlet of the sequencer and to the outlet of the dual-module counter, capable of receiving said third signal and said fourth signal, said fixed counter being capable of detecting the state S and producing the fifth signal as a function of the state S,
- production of a fourth output signal by the variable counter every N periods of a clock signal coming from said resonator,
- detection of the state S less than or equal to N, with the aim of producing a fifth signal capable of modifying the load capacity of said oscillator.
Dependencies are inferred from the claim text.