Amplifier linearization for the local multipoint distribution system application

The deployment of the local multipoint distribution systems (LMDS) is not too far off in the future. Challenging milestones are now being tackled, such as the design of the hub and end user transmitter amplifier. The design goals placed on this amplifier at 28 GHz make linearization an inevitable choice. Of the published linearization techniques, the feedback+feedforward design shows the most promising solution for an LMDS implementation. This design is adaptive, offers fairly simple implementation, and does not decrease the overall gain of the amplifier as a typical feedback system does. Since designing an amplifier for linearity and gain is difficult at 28 GHz, sacrificing gain will only make problems worse. This technique is a solution to the feedback dilemma and is effective in reducing distortion.