| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a high-efficiency power amplifier module equipped with a function to prevent an amplifying device from breaking down due to a standing wave caused by the reflection from an antenna end or the like during load change and a high breakdown strength. SOLUTION: This module prevents output increase and breakdown of GaAs- HBT by suppressing a collector current in such a way as to detect and cancel an excess current flowing in a base of a final stage amplification part GaAs- HBT during load change. The module also avoids applying an excessive voltage and current to the output stage GaAs-HBT, using at the same time a function to decrease gradually an idling current when a power voltage increases and a clipping function of a diode connected in parallel with the output stage GaAs- HBT. Thus, a breakdown strength of the power amplifier module is improved, and a device breakdown during load change is prevented. Moreover, reduction of impacts of a manufacturing deviation and temperature fluctuation in current amplification factor of GaAs-HBT and a high production yield are realized, which contributes to production at a lower cost.</p> |
