| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a class D amplifier wherein a transistor pair of a complementary symmetry is driven by a drive signal with a proper bias and an overcurrent flowing in the transistor pair is detected. <P>SOLUTION: A differential amplifier 103a calculates a difference between an input signal Pa and a power supply voltage +VL being a prescribed voltage, produces a difference signal Psa whose level is shifted toward a power supply voltage +VH by a resistor R2a acting like a pull-up function, an amplifier 104a amplifies the signal Psa to produce a drive signal Pga in matching with a bias of a transistor FETa. Further, similarly an amplifier 104b produces a drive signal Pgb. A current mirror circuit 101a detects a voltage drop VRLa caused across a resistor RLa connected between a transistor FETa and the power supply voltage +VH, and a current mirror circuit 101b detects a voltage drop VRLb caused across a resistor RLb connected between a transistor FETb and the power supply voltage -VH and the presence of the production of an overcurrent is detected by producing currents Ia, Ib corresponding to the voltage drops VRLa, VRLb. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
