Embodiments can provide individualized controlling of noise injection during startup of a crystal oscillator. In some embodiments, a simple learning block can be placed in parallel to a crystal oscillator circuit to control noise injection during the startup of the crystal oscillator. The learning block can be configured to control the noise injection during the startup of the crystal oscillator by determining whether the crystal oscillator has been stabilized. In some implementations, an adjustment block may be employed to adjust the count determined by the learning block based on one or more characteristics of the crystal oscillator during a startup of the crystal oscillator. In some embodiments, a simple block that creates a negative capacitance can be configured in parallel to the crystal oscillator.

A random code generator includes a power source, a sensing circuit, a first memory cell and a second memory cell. A first terminal of the first memory cell is connected with the power source. A second terminal of the first memory cell is connected with the sensing circuit. A first terminal of the second memory cell is connected with the power source. A second terminal of the second memory cell is connected with the sensing circuit. The power source provides a supplying voltage to both the first memory cell and the second memory cell during an enrollment. A random code is then determined according to the resistance difference between the first memory cell and the second memory cell after the enrollment.

A random code generator includes a power source, a sensing circuit, a first memory cell and a second memory cell. A first terminal of the first memory cell is connected with the power source. A second terminal of the first memory cell is connected with the sensing circuit. A first terminal of the second memory cell is connected with the power source. A second terminal of the second memory cell is connected with the sensing circuit. The power source provides a supplying voltage to both the first memory cell and the second memory cell during an enrollment. A random code is then determined according to the resistance difference between the first memory cell and the second memory cell after the enrollment.

A voltage control device includes a first charge pump, a first power switch, a second charge pump, a second power switch, and a third power switch. The first charge pump generates a first application voltage according to the first system voltage. The first power switch has a first input terminal for receiving the first system voltage, a second input terminal for receiving the first application voltage, and an output terminal. The second charge pump generates a second application voltage according to a voltage received by the input terminal of the second charge pump. The second power switch has an input terminal for receiving the second application voltage, and an output terminal. The third power switch has a first input terminal coupled to the output terminal of the first charge pump, a second input terminal coupled to the output terminal of the second charge pump, and an output terminal.

An active noise source apparatus includes a pair of a first and second switched-biased noise amplifier branches (22, 23). A directional coupler (24) having a pair of input ports (3, 4) connected to combine the noise outputs from the first and second switched-biased noise amplifiers. One output port (4) of the directional coupler (24) is connected to a matched termination (Rtermination) and another output port (2) of the directional coupler (24) is connected to an output (25) of the active noise source.

An active noise source apparatus includes a pair of a first and second switched-biased noise amplifier branches (22, 23). A directional coupler (24) having a pair of input ports (3, 4) connected to combine the noise outputs from the first and second switched-biased noise amplifiers. One output port (4) of the directional coupler (24) is connected to a matched termination (Rtermination) and another output port (2) of the directional coupler (24) is connected to an output (25) of the active noise source.

Embodiments can provide individualized controlling of noise injection during startup of a crystal oscillator. In some embodiments, a simple learning block can be placed in parallel to a oscillator circuit to control noise injection during the startup of the crystal oscillator. The learning block can be configured to control the noise injection during the startup of the crystal oscillator by determining whether the crystal oscillator has been stabilized. In some embodiments, an adjustment block may be employed to adjust the count determined by the learning block based on one or more measured characteristics of the crystal oscillator during a startup of the crystal oscillator. In some embodiments, a simple block that creates a negative capacitance can be configured in parallel to the crystal oscillator.

Embodiments can provide individualized controlling of noise injection during startup of a crystal oscillator. In some embodiments, a simple learning block can be placed in parallel to a oscillator circuit to control noise injection during the startup of the crystal oscillator. The learning block can be configured to control the noise injection during the startup of the crystal oscillator by determining whether the crystal oscillator has been stabilized. In some embodiments, an adjustment block may be employed to adjust the count determined by the learning block based on one or more measured characteristics of the crystal oscillator during a startup of the crystal oscillator. In some embodiments, a simple block that creates a negative capacitance can be configured in parallel to the crystal oscillator.

Methods and systems are provided for an awareness intelligence headphone with an always listening mode. Headphone units share the ability to output audio sound to a user, but may not provide additional functionality that users may require. A headphone unit with the always listening mode is used to analyze ambient noise surrounding the headphone unit in order to detect predetermined sounds, issue alerts to a user, and respond to an input command from the user.

A headset with a proximity control is provided. The headset comprises at least a first earpiece, a second earpiece, and a control device. To reduce the power consumption of the headset, the control device is configured to determine proximity between the first earpiece and the second earpiece, and, depending on the determined proximity, to set the headset to a low-power mode, in which at least one component of the headset is disabled to save power.