| 摘要 |
<p>An amplifying circuit with a small current consumption. The operating current of a differential amplifier (A1), which is the main component of the amplifying circuit, is controlled by a first current circuit (7), which is a fixed constant-current source, and a second current circuit (A4), which is a variable current source. The current of the second current circuit (A4) is controlled by an input audio signal with the voltage subjected to full-wave rectification. As a result, when the amplitude of the input signal is small, only a slight operating current is consumed by the first current circuit (7), thereby saving electricity. On the other hand, when the amplitude of an input audio signal is large, the current of the second current circuit (A4) also increases therewith, so that the amplifier flows a sufficiently large output current. Thus, it is possible to amplify the current in correspondence with the amplitude of an input signal, while reducing the operating current when the amplitude of an input signal is small, thereby reducing the current consumption. <IMAGE></p> |
