Clock circuit with programmable load capacitors
AssigneeSilicon Laboratories Inc.
InventorsWenjung Sheng, Shyam Somayajula, Xue-Mei Gong
Life of this patent
Estimating the term…
Abstract
In one embodiment, the present invention includes methods and apparatus for providing initial control values to programmable load capacitors of an oscillator, such as that of a real time clock circuit. Using the initial values, the real time clock circuit may begin operation, enabling additional circuitry within an integrated circuit to begin operation. This additional circuitry may cause operating values to program the load capacitors to provide a desired reference clock based on a given system's requirements.
Claims21
A method comprising:
- providing an initial value for load capacitors of an oscillator while an associated integrated circuit is powered down;
- supplying a reference clock from the oscillator to the associated integrated circuit using the initial value;
- and
- setting an operating value for the load capacitors using the associated integrated circuit after it is powered up.
An integrated circuit comprising:
- an analog circuit portion of a real time clock, the analog circuit portion including programmable load capacitors;
- and
- a digital circuit portion of the real time clock, the digital circuit portion to provide an initial control signal to the programmable load capacitors upon power up of the real time clock.
A wireless system comprising:
- a transceiver comprising a first clock circuit to generate a reference clock signal, the first clock circuit including capacitors fabricated using a substrate of the transceiver to provide a load to a crystal coupled to the transceiver, wherein the capacitors are programmable based on a characteristic of the crystal and a desired frequency of the reference clock signal;
- and
- an antenna coupled to the transceiver.
Dependencies are inferred from the claim text.