| 摘要 |
PURPOSE:To prevent the generation of signal distortion at an output stage by connecting a resistance connected in series to a by-passing unidirectional element, to a switching element at the output stage, which performs the pulse-width modulation and amplification of an audio analog signal, as a parallel load. CONSTITUTION:An audio analog signal inputted to a terminal IN is sampled by a PWM modulator 1, which outputs a PWM signal. It is amplified by a driver 2, whose output is inputted to a power amplifier 3 consisting of a couple of complementary output switching transistor TRs Q1 and Q2. The output V0 of the amplifier 3 performs the push-pull drive of a load 5 through an LPF4. To the TRs Q1 and Q2, dioces D1 and D2 and series resistances R1 and R2 are connected. With this constitution, the envelope waveform of the voltage V0 can be made vertically symmetric by selecting the resistances R1 and R2. Therefore, the output of the LPF4 has no signal distortion of the envelope waveform. |
