Circuit and method of reducing pop-up noise in a digital amplifier
AssigneeSamsung Electronics Co., Ltd.
InventorsSoo-Hyoung Lee, Wang-Seup Yeum, Yong-Jin Cho, In-Bock Lee
Life of this patent
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Abstract
A circuit of reducing a pop-up noise in a digital amplifier includes a switch unit and a switch signal generator. The switch unit is coupled in parallel to an output load between an output node of the digital amplifier and a reference node. The switch unit controls a current flowing through the output load by forming a conduction path between the output node and the reference node in response to a switch signal. The switch signal generator generates the switch signal in response to a switch control signal indicating a power-on or a power-off. The pop-up noise is reduced by the conduction path that is formed when the digital amplifier is powered on or off.
Claims25
A circuit for use in a digital amplifier, comprising:
- a switch unit coupled to an output load between an output node of the digital amplifier and a reference node, the switch unit configured to control a current flow through the output load by forming a conduction path between the output node and the reference node in response to a switch signal;
- and
- a switch signal generator configured to generate the switch signal in response to a switch control signal indicating a power-on or a power-off,
- wherein the switch unit comprises a plurality of NMOS transistors coupled in parallel to each other between the output node and the reference node, each gate of the NMOS transistors receiving a respective switch signal.
A digital amplifier for driving an output load that is coupled between an output node and a reference node, comprising:
- a class-D driving circuit configured to amplify a pulse width modulation (PWM) signal based on a first power supply voltage and a second power supply voltage and to output the amplified PWM signal;
- a low-pass filter configured to convert the amplified PWM signal to an analog signal and to output the analog signal to the output node;
- a reference voltage generator configured to output a reference voltage to the reference node, the reference voltage corresponding to an average of the first power supply voltage and the second power supply voltage;
- and
- a pop-up noise reduction circuit configured to control current flow through the output load by forming a conduction path between the output node and the reference node in response to a switch control signal indicating a power-on or a power-off,
- wherein the pop-up noise reduction circuit comprises:
- a switch unit coupled in parallel to the output load between the output node and the reference node, the switch unit being configured to control the current flowing through the output load by forming N number of conduction paths between the output node and the reference node in response to N number of switch signals, where N is a natural number;
- and
- a switch signal generator configured to generate the N number of switch signals in response to the switch control signal.
A method of reducing a pop-up noise in a digital amplifier, the digital amplifier driving an output load that is coupled between an output node and a reference node, the method comprising:
- forming a conduction path between the output node and the reference node in response to a switch control signal indicating a power-on or a power-off;
- amplifying a pulse width modulation (PWM) signal based on a first power supply voltage and a second power supply voltage;
- converting the amplified PWM signal to an analog signal and outputting the analog signal to the output node;
- and
- applying a reference voltage to the reference node, the reference voltage corresponding to an average of the first power supply voltage and the second power supply voltage,
- wherein the conduction path comprises a plurality of NMOS transistors coupled in parallel to each other between the output node and the reference node, each gate of the NMOS transistors receiving a respective switch signal.
Dependencies are inferred from the claim text.