Reducing duration of start-up period for a crystal oscillator circuit

An electronic apparatus, comprising

• at least one crystal oscillator circuit;
• wherein each of the at least one crystal oscillator circuit comprises:
• a crystal;
• oscillator circuitry connected to the crystal and configured to generate a crystal oscillation signal at an oscillation frequency;
• and
• a kick-start circuit configured to inject a number of pulses into the crystal during a start-up period of the crystal oscillator circuit,
• wherein the oscillator circuitry comprises a first differential pair of transistors and a second differential pair of transistors, the second differential pair of transistors being complementary to the first differential pair of transistors, and wherein the oscillator circuitry is configured to operate in a selectable one of at least an oscillating mode and a start-up mode;
• wherein the first differential pair of transistors, in the oscillating mode, are cross-coupled so that:
• a gate terminal of a first transistor of the first differential pair is coupled to a drain terminal of a second transistor of the first differential pair;
• and
• a gate terminal of the second transistor of the first differential pair is coupled to a drain terminal of the first transistor of the first differential pair;
• each one of the drain terminals of the first and second transistors of the first differential pair further being coupled to a terminal of the crystal to generate the crystal oscillation signal at the oscillation frequency;
• and
• wherein the second differential pair of transistors, in the oscillating mode, are cross-coupled so that:
• a gate terminal of a first transistor of the second differential pair is coupled to a drain terminal of a second transistor of the second differential pair;
• and
• a gate terminal of the second transistor of the second differential pair is coupled to a drain terminal of the first transistor of the second differential pair;
• and
• each one of the drain terminals of the first and second transistors of the second differential pair are coupled to a terminal of the crystal to generate the crystal oscillation signal at the oscillation frequency;
• and
• wherein the kick-start circuit, in the start-up mode, is configured to drive the gate terminals of the first and second transistors of the first differential pair with the number of pulses during the start-up period of the crystal oscillator circuit.

A crystal oscillator circuit, comprising:

• a crystal;
• oscillator circuitry connected to the crystal and configured to generate a crystal oscillation signal at an oscillation frequency;
• and
• a kick-start circuit configured to inject a number of pulses into the crystal during a start-up period of the crystal oscillator circuit,
• wherein the oscillator circuitry comprises a first differential pair of transistors and is configured to operate in a selectable one of at least an oscillating mode and a start-up mode;
• wherein the first differential pair of transistors, in the oscillating mode, are cross-coupled so that:
• a gate terminal of a first transistor of the first differential pair is coupled to a drain terminal of a second transistor of the first differential pair;
• and
• a gate terminal of the second transistor of the first differential pair is coupled to a drain terminal of the first transistor of the first differential pair;
• each one of the drain terminals of the first and second transistors of the first differential pair further being coupled to a terminal of the crystal to generate the crystal oscillation signal at the oscillation frequency;
• and
• wherein the kick-start circuit, in the start-up mode, is configured to drive the gate terminals of the first and second transistors of the first differential pair with the number of pulses during the start-up period of the crystal oscillator circuit, wherein the kick-start circuit comprises an oscillator dedicated to generating the number of pulses, and wherein the dedicated oscillator is configured to be locked to an external reference frequency.

An electronic apparatus, comprising

• at least one crystal oscillator circuit;
• wherein each of the at least one crystal oscillator circuit comprises:
• a crystal;
• oscillator circuitry connected to the crystal and configured to generate a crystal oscillation signal at an oscillation frequency;
• and
• a kick-start circuit configured to inject a number of pulses into the crystal during a start-up period of the crystal oscillator circuit,
• wherein the oscillator circuitry comprises a first differential pair of transistors and is configured to operate in a selectable one of at least an oscillating mode and a start-up mode;
• wherein the first differential pair of transistors, in the oscillating mode, are cross-coupled so that:
• a gate terminal of a first transistor of the first differential pair is coupled to a drain terminal of a second transistor of the first differential pair;
• and
• a gate terminal of the second transistor of the first differential pair is coupled to a drain terminal of the first transistor of the first differential pair;
• each one of the drain terminals of the first and second transistors of the first differential pair further being coupled to a terminal of the crystal to generate the crystal oscillation signal at the oscillation frequency;
• and
• wherein the kick-start circuit, in the start-up mode, is configured to drive the gate terminals of the first and second transistors of the first differential pair with the number of pulses during the start-up period of the crystal oscillator circuit, wherein the kick-start circuit comprises an oscillator dedicated to generating the number of pulses, and wherein the dedicated oscillator is configured to be locked to an external reference frequency.