US 2026/0303018 A1 · CRYSTAL OSCILLATOR

Abstract

An embodiment control circuit for controlling a value of a charge capacitor of a crystal oscillator is configured to receive an initial target value. The control circuit is configured to receive a start-up signal for starting the crystal oscillator. In response to the start-up signal, the control circuit is configured to supply a control value of the charge capacitor equal to the initial target value for a first time period. The initial target value is determined so that, during the first time period, a ratio gm/gmcrit is greater than or equal to 5, where gm is a transconductance of the crystal oscillator and gmcrit is a critical transconductance of the crystal oscillator determined by a current value of the charge capacitor, a frequency of oscillations, an equivalent series resistance value of a crystal of the crystal oscillator, and a value of a shunt capacitor of the crystal of the crystal oscillator.

Claims20

Dependent claims

A control circuit configured to control a value of a charge capacitor of a crystal oscillator, the control circuit configured to:

receive an initial target value;
receive a start-up signal for starting the crystal oscillator;
and
in response to the start-up signal, supply a control value of the charge capacitor equal to the initial target value for a first time period,
wherein the initial target value is determined so that, during the first time period, a ratio gm/gmcrit is greater than or equal to 5, where gm is a transconductance of the crystal oscillator and gmcrit is a critical transconductance of the crystal oscillator determined by a current value of the charge capacitor, a frequency of oscillations, an equivalent series resistance value of a crystal of the crystal oscillator, and a value of a shunt capacitor of the crystal of the crystal oscillator.

2 more elements

A method of controlling a value of a charge capacitor of a crystal oscillator, comprising:

receiving, by a control circuit for controlling the charge capacitor, an initial target value;
receiving, by the control circuit, a start-up signal for starting the crystal oscillator;
and
in response to the start-up signal, supplying, by the control circuit, a control value of the charge capacitor equal to the initial target value for a first time period,
wherein the initial target value is determined so that, during the first time period, a ratio gm/gmcrit is greater than or equal to 5, where gm is a transconductance of the crystal oscillator and gmcrit is a critical transconductance of the crystal oscillator determined by a current value of the charge capacitor, a frequency of oscillations, an equivalent series resistance value of a crystal of the crystal oscillator, and a value of a shunt capacitor of the crystal of the crystal oscillator.

2 more elements

Dependencies are inferred from the claim text.

Crystal oscillator

Life of this patent

Crystal oscillator

Life of this patent

Abstract

Claims20