HIGH EFFICIENCY, HIGH POWER WCDMA LDMOS TRANSISTORS FOR BASE STATIONS

摘要

OEMs, operators and manufacturers of base station RF power amplifiers are constantly striving for greater efficiency, whether it be in the number of connections (calls) that can be made via a base station or the amount of DC power needed to make those calls. For both scenarios, the RF power amplifier plays a key role. First, it is the part of a base station that consumes the most DC power in order to generate the substantial amount of RF power required to maintain a reliable wireless connection for many users. Second, the linearity of the power amplifier determines how many calls can be handled reliably without creating significant interference in neighboring channels in the assigned frequency bands. Today, laterally diffused metal oxide semiconductor (LDMOS) technology is the choice for base station RF power amplifiers because it is reliable, and meets current market needs for performance and cost, with even greater performance improvements possible if the LDMOS technology is further refined. Common techniques to improve efficiency at the power amplifier level are the Doherty principle, (digital) pre-distortion and, in the case of multicarrier amplifiers, a feedforward concept. What is paramount, however, is to ensure that the RF power amplifier delivers the required base performance. This article describes the trade-offs between linearity, gain and efficiency that can be made for state-of-the-art LDMOS technology.