| 摘要 |
<P>PROBLEM TO BE SOLVED: To reduce a degradation of a ramp-up or ramp-down switching spectrum. <P>SOLUTION: Initial and final stage bias circuits 81, 83 determine idling currents of initial and final stage amplification circuits 41, 43. A power detection circuit 5, 6 generates a power detection signal V<SB POS="POST">DET</SB>responsive to a signal level of a final stage output signal Pout. The detection signal V<SB POS="POST">DET</SB>and a target power signal V<SB POS="POST">RAMP</SB>are supplied to an error amplifier 7, and a power control voltage V<SB POS="POST">APC</SB>is supplied to an input of a control signal enhancement circuit 9, whose output generates an enhanced control signal V<SB POS="POST">EN</SB>. The control signal enhancement circuit 9 has a predetermined nonlinear input/output characteristic. The enhanced control signal V<SB POS="POST">EN</SB>is supplied to the initial and final stage bias circuits 81, 83, so that the enhanced control signal V<SB POS="POST">EN</SB>controls the idling currents of the initial and final stage amplification circuits 41, 43 to compensate for a reduced control gain of an RF power amplifier. <P>COPYRIGHT: (C)2013,JPO&INPIT |
