National Semiconductor Corporation

Iron Device Corporation

Hwang Soo Son

Jin Sung Kim

Ki Tae Park

Kyu Don Choi

The present invention relates to a speaker driver and an operation method thereof and includes an amp part configured to output a pulse voltage, in which an input signal is amplified on the basis of a supply voltage, to drive a capacitive speaker that generates sound by a driving voltage so that the driving voltage formed by filtering the pulse voltage is applied to the capacitive speaker, and a controller configured to adjust a magnitude of an input audio signal in a high frequency range and transmit the input audio signal to the amp part as the input signal to limit an overcurrent applied to the capacitive speaker by the driving voltage having a high frequency.

Speaker driver and operation method thereof

A circuit for TDMA noise reduction is provided, which may be used in a mobile phone. The circuit includes a first audio amplifier, a second audio amplifier, and a switch. The circuit is attachable to a stereo headphone with two speakers, each speaker having two inputs. The first speaker has one input that is coupled to one input of the second speaker. The other input of each speaker is coupled to a corresponding audio amplifier. During a talk mode for the mobile phone, the common input of the two speakers is left floating. In this mode, the TDMA noise is substantially cancelled, and the sound is differential monophonic. When the mobile phone is not in a talk mode, the common input of the speakers is driven to Vdd/2 or ground, so that the sound is stereophonic.

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Cupertino, CA, United States of America

Hwang Soo Son