| 摘要 |
<p>In a portable apparatus in a digital cellular system in which transmission and reception is simultaneously conducted in a particularly wide variable output range, efficiency is improved in a low-power output operation and there is minimized the influence upon discontinuous output waveforms appearing in a gain changing operation. There are included a distributor to distribute an input signal to two paths, a first gain control amplifier, a linear power amplifier, a driver amplifier, a filter, a switching circuit to turn power of the linear power amplifier on and off, and a second gain control amplifier. Outputs from the linear power and gain control amplifiers are mixed with each other by a mixer. Gains of these amplifiers are separately controlled by a control circuit, which also controls on and off of the switching circuit. <IMAGE></p> |
