Rapid turn-on, controlled amplitude crystal oscillator
AssigneeLucent Techmologies Inc.
InventorDale Harvey Nelson
Life of this patent
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Abstract
A crystal tank circuit is connected between the ac cross-coupled outputs of two transistors that are selectively biased to an appropriate common mode voltage to cause rapid build-up of oscillation when the circuit is turned on and in which oscillation is sustained in the desired mode regardless of battery voltage fluctuation without wasting power. The differentially driven frequency-controlling crystal tank circuit receives balanced driving voltage excursions from the circuit.
Claims9
A multivibrator having a pair of cross-connected transistors, comprising:
- a. first and second series-connected resistors (R26, R25) for applying a bias to initiate oscillation of said transistors;
- b. a circuit (M12, M5, M13, M14) for applying a current through one of said resistors proportional to a peak amplitude of oscillation of said transistors;
- and
- c. a circuit (M33, M34) for limiting a maximum current through said one of said resistors to limit a maximum amplitude of oscillation.
A multivibrator according to clam 1 including a frequency-defining tank circuit connected between corresponding electrodes of said cross-connected transistors.
An oscillator circuit comprising:
- a. a frequency-defining tank circuit linking a pair of cross-coupled transistors;
- and
- b. a pair of transistors of opposite conductivity type to said cross-coupled transistors for determining the bias to said cross-coupled transistors;
- and
- c. an oscillation amplitude sensing circuit for controlling the bias of said opposite-conductivity type transistors.
Dependencies are inferred from the claim text.