Low-latency start-up for a monolithic clock generator and timing/frequency reference

A method of providing low-latency start-up for a harmonic oscillator, the method comprising:

• generating a first current;
• generating a second current, front a parameter-dependent current source having at least one complementary to absolute temperature (CTAT) configuration, proportional to absolute temperature (PTAT) configuration, or proportional to absolute temperature squared (PTAT2)configuration;
• generating a first reference voltage and a second reference voltage;
• comparing the first reference voltage to the second reference voltage;
• when the second reference voltage is greater than the first reference voltage, providing the first current to the oscillator;
• and
• when the second reference voltage is not greater than the first reference voltage, providing the second current to the oscillator.

A system for low-latency start-up of a free-running harmonic oscillator, the system comprising:

• a harmonic oscillator;
• a reference voltage generator adapted to generate a first reference voltage and a second reference voltage;
• a comparator coupled to the reference voltage generator, the comparator adapted to compare the first reference voltage to the second reference voltage and to provide a first comparison signal when the second reference voltage is greater than the first reference voltage and to provide a second comparison signal when the second reference voltage is not greater than the first reference voltage;
• a bias controller coupled to the comparator, the bias controller adapted to switch a first current to the harmonic oscillator in response to the first comparison signal and to switch a second current to the oscillator in response to the second comparison signal;
• and
• a parameter-dependent current source adapted to provide the second current, the parameter-dependent current source having at least one complementary to absolute temperature (CTAT) configuration, proportional to absolute temperature (PTAT) configuration, or proportional to absolute temperature squared (PTAT2) configuration.

A start-up apparatus for a free-running harmonic oscillator, the apparatus comprising:

• a reference voltage generator adapted to generate a first reference voltage and a second reference voltage;
• a comparator coupled to the reference voltage generator, the comparator adapted to compare the first reference voltage to the second reference voltage and to provide a first comparison signal when the second reference voltage is greater than the first reference voltage and to provide a second comparison signal when the second reference voltage is not greater than the first reference voltage;
• a bias controller coupled to the comparator, the bias controller adapted to switch a first current to the oscillator in response to the first comparison signal and to switch a second current to the oscillator in response to the second comparison signal;
• and
• a parameter-dependent current source adapted to provide the second current, the parameter-dependent current source having at least one complementary to absolute temperature (CTAT) configuration, proportional to absolute temperature (PTAT) configuration, or proportional to absolute temperature squared (PTAT2) configuration.

An apparatus comprising:

• a harmonic oscillator,
• a first current source adapted to provide a first current;
• a second current source adapted to provide a second current, the second current source having at least one complementary to absolute temperature (CTAT) configuration, proportional to absolute temperature (PTAT) configuration, or proportional to absolute temperature squared (PTAT2) configuration;
• a bias current monitor coupled to the first current source and the second current source, the bias current monitor adapted to provide a control signal;
• and
• a bias controller coupled to the bias current monitor, the bias controller adapted to switch the first current from the oscillator in response to the control signal.

A start-up apparatus for a harmonic oscillator, the apparatus comprising:

• a reference voltage generator adapted to generate a reference voltage;
• a first current source adapted to provide a first current;
• a second current source adapted to provide a second current, the second current source having at least one complementary to absolute temperature (CTAT) configuration, proportional to absolute temperature (PTAT) configuration, or proportional to absolute temperature squared (PTAT2) configuration;
• a comparator coupled to the reference voltage generator, the comparator adapted to compare the reference voltage to a voltage proportional to the second current and to provide a control signal;
• a bias controller coupled to the comparator, the bias controller adapted to switch the first current from the oscillator in response to the control signal.