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US 6,285,264 B1Granted
Crystal oscillator with frequency trim
AssigneeCypress Semiconductor Corporation
InventorEric N. Mann
Life of this patent
Estimating the term…
Abstract
A timing crystal oscillator circuit that may be tuned after production. The circuit generally comprises a microprocessor configured to present one or more control signals, one or more load devices that may be activated in response to the control signals and a crystal oscillator for presenting an output signal having a frequency which is generally dependent on the number of load devices activated.
Claims20
An apparatus comprising:
- a circuit configured to provide a variable magnitude load;
- and
- an oscillator circuit configured to generate an output signal having (i) a frequency determined in response to a magnitude of said variable magnitude load and (ii) a voltage swing determined in response to a clamp circuit, said oscillator comprising (i) a first current source configured to limit a first current available to said oscillator in response to a reference current, and (ii) a second current source configured to limit a second current to said oscillator in response to a reference current mirror.
A method for generating a variable frequency clock signal, comprising the steps of:
- (A) generating a variable magnitude load;
- (B) generating said variable frequency clock signal having (i) a frequency which is dependent on the magnitude of the variable magnitude load and (ii) a voltage swing determined in response to a clamp circuit, wherein said clock signal is an output of an oscillator;
- (C) limiting a first current available to said oscillator in response to a reference current;
- and
- (D) limiting a second current to said oscillator in response to a reference current mirror.
2 more elements
A circuit comprising:
- means for providing a variable magnitude load ;
- and
- means for providing an output signal having (i) a frequency determined in response to the magnitude of said variable magnitude load and (ii) a voltage swing determined in response to a clamp circuit wherein said means for providing said output signal comprises
- means for limiting a first current available to said means for providing said output signal in response to a reference current;
- and
- means for limiting a second current to said means for providing said output signal in response to a reference current mirror.
3 more elements
Dependencies are inferred from the claim text.