| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a variable output amplifier that implements increased efficiency at low output by reducing a circuit loss at low output. <P>SOLUTION: The variable output amplifier includes: a transistor 11 connected in parallel with a transistor 5; and a bias control circuit 12 for applying bias voltages such that only the transistor 5 operates when reducing an average power level of signal output below a predetermined value, and applying bias voltages such that both transistors 5, 11 operate when increasing the average power level of signal output above the predetermined value. The configuration can output signal outputs of the transistors 5, 11 as they are without using a bypass path whether at low output or at high output to implement a reduced circuit loss at low output and increased efficiency at low output. <P>COPYRIGHT: (C)2013,JPO&INPIT |
