Method and apparatus for optimizing an oscillator start up time
AssigneeMotorola, Inc.
InventorsKeith Edward Jackoski, John Wayne Simmons, Gerald Paul Schwieterman
Life of this patent
Estimating the term…
Abstract
An oscillator circuit (10) having an optimized start up time includes an inverting amplifier (12) coupled in parallel to a crystal (14), a first bank of capacitors (16) coupled to the crystal, and a second bank of capacitors (20) switchably coupled (18) in parallel to the frequency resonant network, wherein the second bank of capacitors has a higher capacitance load than the first bank of capacitors. The oscillator circuit may also include a processor (62) for controlling when the second bank of capacitors gets switched and coupled to the crystal.
Claims18
A method of optimizing an oscillator start up time, comprising the steps of:
- applying a minimum capacitance load to an oscillator circuit;
- enabling the oscillator circuit using the minimum capacitance load;
- sensing a stable oscillator output at a first frequency;
- and
- applying a second capacitance load when the stable oscillator output at the first frequency is sensed to provide a desired oscillation frequency.
A method of optimizing an oscillator start up time, wherein an oscillator circuit includes a first bank of capacitors and a second bank of capacitors, the method comprising the steps of:
- applying the first bank of capacitors to the oscillator circuit, wherein the first bank of capacitors has a minimum capacitance;
- enabling the oscillator circuit using the first bank of capacitors;
- and
- applying the second bank of capacitors when the oscillator circuit is resonating at a prescribed frequency with a stable output.
An oscillator circuit having an optimized start up time, comprising:
- an inverting amplifier coupled in parallel to a frequency resonant network;
- a first bank of capacitors coupled to the frequency resonant network;
- a second bank of capacitors switchably coupled in parallel to the frequency resonant network, wherein the second bank of capacitors has a higher capacitance load than the first bank of capacitors and wherein a first capacitance load of the first bank of capacitors is used to enable the oscillator circuit at start up time until a stable oscillator output is sensed at a first frequency whereupon the second bank of capacitors is applied to provide a desired oscillation frequency.
A selective call device, comprising:
- a receiver having an oscillator circuit and a decoder;
- and
- a processor coupled to the oscillator, wherein the processor is programmed to optimize the start up time of the oscillator circuit by:
- applying a minimum capacitance load to the oscillator circuit;
- enabling the oscillator circuit using the minimum capacitance load;
- sensing a stable output oscillating at a prescribed frequency;
- and
- applying a second capacitance load when the stable output oscillating at the prescribed frequency is sensed to provide a desired frequency tuning point.
Dependencies are inferred from the claim text.