Linear Front End Module for 4G/5G LTE Advanced Applications

With explosive band proliferation as well the use of carrier aggregation (CA), multiple input multiple output (MIMO) techniques and 5G, research in the area of improving the cost, performance and the size of RF transmit solutions is very active with many developments over the past few years. The proliferation of worldwide smartphones has been in part possible due to increase computational power of CMOS technology in lower feature nodes as 7nm/14nm. This has also made it possible to enhance RF CMOS through digital signal processing (DSP) and digital calibration. Despite this progress there is a shift in terms of what parts of the RF system are portioned in advanced CMOS nodes and what blocks are left and integrated together with other analogue and RF blocks in a front-end module (FEM). This paper proposes a solution for this partitioning for lower cost and size and with high linearity performance and low noise which is mandatory for new 4G/5G multimode multiband (MMBA) FEM module. A 2.3GHz - 2.7GHz broadband CMOS FDD/TDD LTE Band 7, 38, 40 and 41 power amplifier (PA) fully integrated with a fast envelope tracker (ET) on a single 0.18μm CMOS die is presented, as well a method to integrate with a 4G/5G FEM. The CMOS PA and the tracker achieve a 37% overall efficiency for 26.5dBm and -39dBc ACLR1. This paper also presents how this module integrates into a full 4G/5G FEM for mobile applications.