A Switch-Type Power Amplifier and Its Application to a CDMA Cellphone

摘要

To address the demand for miniaturization and low cost in a cellphone, we aimed to eliminate the isolator and DC-DC converter. We propose a novel switch-type power amplifier (PA) using a strong junction PHEMT (JPHEMT) PA instead of HBT from the point of view of the performance under load-impedance variation. In high output power mode, the performance of this PA is the same as that of the conventional PA. In low output power mode, it operates as a single-stage PA and satisfies distortion characteristics without causing deterioration of efficiency.