| 摘要 |
PROBLEM TO BE SOLVED: To provide a digital amplifier having the advantage in attaining miniaturization and low cost. SOLUTION: A switching circuit 16 is turned on/off responding to "L" and "H" of an input signal Spwm, thereby outputting a driving signal Sd having the same amplitude as that of an operation voltage Vreg from an output terminal 1602. A mute means 18 comprises a plurality of n-channel type field effect transistors TR each connected in parallel between the output terminal 1602 of the switching circuit 16 and the input terminal of a low pass filter 20, and a controller 19 for independently controlling turning on/off each of the transistors TR. Each transistor TR is controlled to be turned on/off on the basis of "H", "L" of control signals CNT1-CNT 9 to be supplied, and a resistance value between the output terminal 1602 and the input terminal 2002 can be increased or decreased like a step. COPYRIGHT: (C)2005,JPO&NCIPI
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