MMIC Doherty PAM having fewer cells suitable for Wibro handset

In this paper, a Doherty is adopted based on the optimum method which is researched how is the number of cells decided in the power stage using InGaP/GaAs HBT. Especially owing to importance of efficiency for carrier amplifier, the unbalanced Doherty structure is used to make carrier amplifier operated near the PldB within the range satisfying linearity for Wibro. At the same time, the method adjusting a sweep spot point for peaking amplifier is also considered to increase linearity. We could realize Wibro PAM by using much fewer cells which is merely 32 cells, therefore PAM is confirmed that it is operated by having characteristics such as low leakage and temperature condition, high linearity and efficiency in the handset. In other words, IMD and ACLR are below -40 dBc and -27 dBc respectively at all output level up to 22 dBm targeted on maximum output, efficiency is 21% at 22 dBm.