| 摘要 |
PROBLEM TO BE SOLVED: To provide a low cost D class power amplifying device which protects an output element effectively and demonstrates the performance of an amplifier fully. SOLUTION: In failure such as short-circuiting at an output terminal, an output element in a D class amplifier unit 1 is protected by disconnecting an input signal to the D class amplifier unit 1. Since input side voltage (or current) of the D class amplifier unit 1 is small compared with the output side, a semiconductor device of low cost and high speed response such as a transistor Q1 is used for this kind of input signal control. Moreover, a protection circuit 4 for operating the element Q1 is configured with simple elements such as a resistor, a diode, and a transistor. Accordingly, a D class power amplifying device 10 for protecting the output element is configured simply and in low cost. Furthermore, when both output current and output voltage of the D class amplifier unit 1 are big, the performance is fully demonstrated because the transistor Q1 is kept off, and signal input to the D class amplifier unit 1 is conducted normally. COPYRIGHT: (C)2004,JPO&NCIPI
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