Reference-less clock circuit
First Claim
1. An integrated circuit comprising:
- a controllable oscillator arranged in an open loop configuration;
a programmable divider circuit coupled to divide an output of the controllable oscillator according to a programmable divide value;
control logic coupled to supply a control word to adjust an output frequency of the controllable oscillator according to a detected temperature;
a non-volatile storage storing a control word, an output of the controllable oscillator determined according to a value of the control word; and
wherein the divide value for the programmable divider circuit is stored in the non-volatile storage.
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Accused Products
Abstract
A programmable reference-less oscillator provides a wide range of programmable output frequencies. The programmable reference-less oscillator is implemented on an integrated circuit that includes a free running controllable oscillator circuit such as a voltage controlled oscillator (VCO), a programmable divider circuit coupled to divide an output of the controllable oscillator circuit according to a programmable divide value. A non-volatile storage stores the programmed divide value and a control word that controls the output of the controllable oscillator circuit. The control word provides a calibration capability to achieve a desired output frequency in conjunction with the programmable divider circuit. Open loop temperature compensation is achieved by adjusting the control word according to a temperature detected by a temperature sensor on the integrated circuit. Additional clock accuracy may be achieved by adjusting the control word for process as well as temperature.
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Citations
20 Claims
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1. An integrated circuit comprising:
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a controllable oscillator arranged in an open loop configuration; a programmable divider circuit coupled to divide an output of the controllable oscillator according to a programmable divide value; control logic coupled to supply a control word to adjust an output frequency of the controllable oscillator according to a detected temperature; a non-volatile storage storing a control word, an output of the controllable oscillator determined according to a value of the control word; and wherein the divide value for the programmable divider circuit is stored in the non-volatile storage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A reference-less oscillator comprising:
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a controllable oscillator circuit; means for dividing an output of the controllable oscillator circuit according to a programmed divide value; a non-volatile storage storing a control word and the programmed divide value, the output of the controllable oscillator circuit determined according to a value of the control word; and means for adjusting the output of the controllable oscillator circuit according to temperature. - View Dependent Claims (11, 12)
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13. A method for operating an integrated circuit to provide a reference-less oscillator comprising:
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determining a control signal for a controllable oscillator circuit in an open loop configuration, at least in part, according to a stored value in a non-volatile memory; supplying the control signal to the controllable oscillator circuit, thereby determining an output of the controllable oscillator circuit; storing a divide value for a divider circuit in the non-volatile memory; and dividing the output of the controllable oscillator circuit in the divider circuit according to the divide value. - View Dependent Claims (14, 15, 16)
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17. A method of making reference-less oscillator circuit that provides a selected output frequency comprising:
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programming a divide value for a divider circuit coupled to divide a first output signal from a controllable oscillator circuit, a second output signal from the divider circuit having a frequency that differs from the selected output frequency; varying a control value that controls the first output signal from the controllable oscillator circuit until the second output signal from the divider circuit is the selected output frequency; storing the control value associated with generation of the selected output frequency in non-volatile memory; and storing information in the non-volatile memory relating to adjusting the control value according to a detected temperature. - View Dependent Claims (18, 19, 20)
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Specification