| 摘要 |
A linear system and an EER system are used in combination such that the EER system can also be used in a cellular phone with a wide output dynamic range. In the EER system, linear control of an amplifier (909) becomes difficult in the low output range. Thus, use of the EER system is limited to the high output range, and the linear system is used in the low output range as in the past. The power efficiency is improved while requirements of linearity are satisfied by this structure. An effective circuit structure is proposed for a switching control system for two systems. In addition, an up-converter (911) is constituted in combination with a step-down element (912) with high responsiveness, whereby a power supply voltage control circuit for the EER system with a wide control range and high responsiveness is provided. <IMAGE> |
