Crystal oscillator circuit
AssigneeInfineon Technologies AG
InventorHeiko Korner
Life of this patent
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Abstract
A crystal oscillator circuit has capacitors that govern the resonant circuit and are designed such that they can be connected and disconnected, for frequency adjustment. A respective compensation capacitor is connected opposite and in mirror-image form to these capacitors that govern the resonant circuit. This compensation capacitor influences only the dynamic operating point, but has virtually no effect on the oscillation frequency. In consequence, it is not possible to shift the operating point during adjustment of the oscillation frequency, thus ensuring stability of the oscillating system and operation at the desired operating point.
Claims10
A crystal oscillator circuit, comprising:
- an oscillating crystal having a first and a second connection;
- a quick-response amplifier having an input connected to said first connection of said oscillating crystal and an output connected to said second connection of said oscillating crystal;
- a device for operating point adjustment, said device coupling said oscillating crystal to said input of said quick-response amplifier;
- a reference node;
- a first capacitive component for connecting said first connection of said oscillating crystal to said reference node;
- a second capacitive component for connecting said second connection of said oscillating crystal to said reference node;
- and
- a compensation capacitor connected to said input of said quick-response amplifier and to said reference node;
- at least one capacitive component selected from a group consisting of said first capacitive component and said second capacitive component being adjustable;
- and
- said compensation capacitor being adjustable in a complementary manner to said first capacitive component and said second capacitive component.
Dependencies are inferred from the claim text.