Crystal-less clock generator and operation method thereof
First Claim
1. A crystal-less clock generator (CLCG), comprising:
- a first oscillation circuit, controlled by a control signal for generating an output clock signal of the CLCG;
a second oscillation circuit, generating a reference clock signal; and
a control circuit, coupled to the first oscillation circuit for receiving the output clock signal, and coupled to the second oscillation circuit for receiving the reference clock signal, wherein the control circuit is used to generate the control signal for the first oscillation circuit,wherein the control circuit calculates a first difference between a frequency of the output clock signal and a first reference frequency, calculates a second difference between a frequency of the reference clock signal and a second reference frequency, and generates the control signal for the first oscillation circuit according to a relationship between the first difference and the second difference,wherein the control circuit takes a frequency of the output clock signal measured after the first oscillation circuit is initialized to serve as the first reference frequency, and takes a frequency of the reference clock signal measured after the second oscillation circuit is initialized to serve as the second reference frequency.
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Accused Products
Abstract
A crystal-less clock generator (CLCG) and an operation method thereof are provided. The CLCG includes a first oscillation circuit, a second oscillation circuit, and a control circuit. The first oscillation circuit is controlled by a control signal for generating an output clock signal of the CLCG. The second oscillation circuit generates a reference clock signal. The control circuit is coupled to the first oscillation circuit for receiving the output clock signal and coupled to the second oscillation circuit for receiving the reference clock signal. The control circuit is used to generate the control signal for the first oscillation circuit according to the relationship between the output clock signal and the reference clock signal.
38 Citations
31 Claims
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1. A crystal-less clock generator (CLCG), comprising:
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a first oscillation circuit, controlled by a control signal for generating an output clock signal of the CLCG; a second oscillation circuit, generating a reference clock signal; and a control circuit, coupled to the first oscillation circuit for receiving the output clock signal, and coupled to the second oscillation circuit for receiving the reference clock signal, wherein the control circuit is used to generate the control signal for the first oscillation circuit, wherein the control circuit calculates a first difference between a frequency of the output clock signal and a first reference frequency, calculates a second difference between a frequency of the reference clock signal and a second reference frequency, and generates the control signal for the first oscillation circuit according to a relationship between the first difference and the second difference, wherein the control circuit takes a frequency of the output clock signal measured after the first oscillation circuit is initialized to serve as the first reference frequency, and takes a frequency of the reference clock signal measured after the second oscillation circuit is initialized to serve as the second reference frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A crystal-less clock generator (CLCG), comprising:
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a first oscillation circuit, controlled by a control signal for generating an output clock signal of the CLCG; a second oscillation circuit, generating a reference clock signal; and a control circuit, coupled to the first oscillation circuit for receiving the output clock signal, and coupled to the second oscillation circuit for receiving the reference clock signal, wherein the control circuit is used to generate the control signal for the first oscillation circuit according to a relationship between the output clock signal and the reference clock signal, wherein the control circuit comprises; a first time amplifier (TA), wherein an input terminal of the first TA is coupled to an output terminal of the first oscillation circuit, and a gain of the first TA is controlled by a first gain-adjustment signal; a second TA, wherein an input terminal of the second TA is coupled to an output terminal of the second oscillation circuit, and a gain of the second TA is controlled by a second gain-adjustment signal; a time-to-digital converter (TDC), coupled to the first TA to convert at least one output signal of the first TA into an output clock characteristic value, and coupled to the second TA to convert at least one output signal of the second TA into a reference clock characteristic value; and a controller, coupled to the TDC, wherein the controller generates the control signal for the first oscillation circuit according to a relationship between the output clock characteristic value and the reference clock characteristic value. - View Dependent Claims (18, 19, 20, 21)
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22. An operation method of a crystal-less clock generator (CLCG), comprising:
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generating an output clock signal of the CLCG according to a control signal by a first oscillation circuit; generating a reference clock signal by a second oscillation circuit; calculating a first difference between a frequency of the output clock signal and a first reference frequency; calculating a second difference between a frequency of the reference clock signal and a second reference frequency; generating the control signal for the first oscillation circuit according to a relationship between the first difference and the second difference; taking a frequency of the output clock signal measured after the first oscillation circuit is initialized to serve as the first reference frequency; and taking a frequency of the reference clock signal measured after the second oscillation circuit is initialized to serve as the second reference frequency. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31)
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Specification