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US 7,046,082 B2Granted
Electronic device having sound output module
AssigneeRohm Co., Ltd.
InventorsKunihiro Komiya, Tadayuki Sakamoto
Life of this patent
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Abstract
the output amplifiers requiring a bias voltage can be activated or deactivated individually, and a bias acceleration circuit for rapidly increasing the magnitude of a bias voltage in time can be provided in or with the bias circuit, whereby even in case of the capacitance of the capacitor included in the bias circuit being increased for improving the power supply rejection ratio (PSRR), the rise in the bias voltage can be increased so that the pop sound which arises when the bias circuit is activated can be still diminished.
Claims6
A sound output module comprising:
- an output amplifier, which can be activated and deactivated individually, requires a bias voltage, and receives an output from a preamplifier;
- a bias circuit, comprising at least a resistor and a capacitor, which operates to produce said bias voltage, said bias voltage gradually increasing at a time constant determined by a value of the capacitor and in accordance with an ON-state signal sent to said output amplifier;
- and
- a bias adjustment circuit which further increases the magnitude of the bias voltage produced by said bias circuit to a predetermined value within a predetermined period of time.
1 more element
Dependencies are inferred from the claim text.