Evolution of RFIC Handset PAs

Because PAs used in cell phone handsets operate with a battery supply, a high PAE is essential for battery life. It is also important for thermal management on the handset. Linearity is critical for 3G applications or beyond. In addition, cost, size, and reliability are also very important to consider. Higher and higher on-chip integration using various semiconductor technologies is the key to make handset PAs smaller and more cost-effective, enabling more features on the phones. III-V compound technologies are still dominant in today´s handset market due to their superior performance such as PAE, linearity, and ruggedness. Most of the handset PAs using III-V compound technologies are delivered in an over molded multichip module (MCM) package. The physical integration inside the MCM for a GSM PA is shown in Figure 18 and one for a WCDMA PA is shown in Figure 19. Silicon-CMOS technologies are playing catch-up. Further performance improvement and more novel design approaches are needed to displace the dominance of the III-V compound technologies. Silicon-based technologies provide a good solution for single chip integration. Silicon-CMOS multimode/multiband hand-set PAs may provide phone vendors with the lowest cost, smallest size, and most functionality. The PA may eventually be integrated with transceiver and baseband chips to further reduce size and cost.