Transmission apparatus and mobile communication terminal apparatus

摘要

An output level of a transmission apparatus 1 is determined, depending on an attenuation amount of an attenuator 30, a gain of one of a high output level amplification section 17 and a low output level amplification section 18, which is used. A reference voltage Vref(H) is discontinuously changed. Depending on the magnitude of the reference voltage Vref(H), it is determined which of the amplification sections 17, 18 is used, and the attenuation amount of the attenuator 30 and the gain of the amplification section 17, 18 are also determined. When the magnitude of the reference voltage Vref(H) is changed, a sum of the attenuation amount of the attenuator 30 and a gain change amount of a switch amplification section 19 is substantially zero.