Circuit, system, and method for fine tuning crystal frequency accuracy

A system for fine tuning the oscillating frequency of a crystal, comprising:

• a capacitive-resistive network coupled with said crystal for providing a substantially constant capacitance value thereto;
• a switchable capacitive element controllably coupleable to said crystal for providing a switched capacitance value thereto when so coupled;
• a single switching device comprising:
• a switching unit coupled with said switchable capacitance element and controllable for switchably coupling said switchable capacitive element to said crystal at high frequency;
• and
• a switching controller coupled with said switching unit for causing said switching unit to couple said switchable capacitance to said crystal wherein an effective capacitance value associated with said switchable capacitance is achieved with modulating the time said switchable capacitance element is coupled to said crystal according to said oscillating frequency of said crystal;
• and
• a frequency sensor coupled to said switching controller for monitoring said oscillating frequency of said crystal,
• wherein said switchable capacitance is external from an integrated circuit device in which said capacitive-resistive network and said switching unit are disposed.

A method for fine tuning the oscillating frequency of a crystal, comprising:

• applying a static base loading capacitance to said crystal;
• responsive to detecting a change in said oscillating frequency, multiplicatively weighting a second capacitance to achieve an effective weighted capacitance with timed switching multiplexing;
• and
• controllably loading said crystal with said effective weighted capacitance and said static base loading capacitance to achieve a total capacitive loading thereof according to said timed switching multiplexing, wherein a single switching mechanism is used, and wherein said total capacitive loading fine tunes said oscillating frequency to compensate for said change therein, and wherein said second capacitance is external to an integrated circuit device which said static base loading capacitance and said single switching mechanism are disposed.