Dual frequency crystal oscillator
First Claim
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1. An oscillator comprising:
- a first crystal operable to generate a first oscillating signal at a first frequency;
a second crystal coupled to the first crystal and operable to generate a second oscillating signal in response to the first oscillating signal at a second frequency higher than the first frequency; and
a DC restore circuit operable to generate a third oscillating signal comprising a substantially fifty percent duty cycle in response to the second oscillating signal.
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Abstract
An oscillator is disclosed comprising a first crystal operable to generate a first oscillating signal at a first frequency, and a second crystal coupled to the first crystal and operable to generate a second oscillating signal at a second frequency higher than the first frequency. The oscillator further comprises a DC restore circuit operable to generate a third oscillating signal comprising a substantially fifty percent duty cycle in response to the second oscillating signal.
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Citations
22 Claims
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1. An oscillator comprising:
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a first crystal operable to generate a first oscillating signal at a first frequency; a second crystal coupled to the first crystal and operable to generate a second oscillating signal in response to the first oscillating signal at a second frequency higher than the first frequency; and a DC restore circuit operable to generate a third oscillating signal comprising a substantially fifty percent duty cycle in response to the second oscillating signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A disk drive comprising:
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a disk; a head actuated over the disk; a pulse width modulated (PWM) signal generator operable to generate a PWM signal; a spindle motor operable to rotate the disk in response to the PWM signal; a phase-locked loop (PLL) operable to generate a system clock used to process a read signal emanating from the head; and an oscillator comprising; a first crystal operable to generate a first oscillating signal at a first frequency; and a second crystal coupled to the first crystal and operable to generate a second oscillating signal at a second frequency higher than the first frequency, wherein; the PWM signal generator is operable to generate the PWM signal based on the first oscillating signal; and the PLL is operable to generate the system clock based on the second oscillating signal. - View Dependent Claims (11)
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12. A method comprising:
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generating a first oscillating signal at a first frequency using a first crystal; generating a second oscillating signal in response to the first oscillating signal at a second frequency higher than the first frequency using a second crystal coupled to the first crystal; and generating a third oscillating signal comprising a substantially fifty percent duty cycle in response to the second oscillating signal. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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21. A method of operating a disk drive, the disk drive comprising a head actuated over a disk, a pulse width modulated (PWM) signal generator operable to generate a PWM signal, a spindle motor operable to rotate the disk in response to the PWM signal, and a phase-locked loop (PLL) operable to generate a system clock used to process a read signal emanating from the head, the method comprising:
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generating a first oscillating signal at a first frequency using a first crystal; and generating a second oscillating signal at a second frequency higher than the first frequency using a second crystal coupled to the first crystal, wherein; the PWM signal generator is operable to generate the PWM signal based on the first oscillating signal; and the PLL is operable to generate the system clock based on the second oscillating signal. - View Dependent Claims (22)
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Specification