Multi-chip module integrates GaN on top of LDMOS to improve power amplifier energy efficiency.

At the 2021 IEEE Microwave Symposium’s Connected Future Summit, two presentations covered the need for new semiconductor material in support of 6G, but enhancements to CMOS can help with 5G. NXP Semiconductors has added Gallium Nitride (GaN) technology to its multi-chip module platform. The module drives antennas in arrays built into outdoor small cells with greater efficiency that previous modules.

Claiming to be the first to integrate GaN Doherty power amplifier (PA) on LDMOS, NXP expects availability of module samples during Q3 2021 with full production by the end of the year. The company also claims that using GaN will increase efficiency to 52% at 2.8 GHz as opposed to 44% for its LDMOS devices. The’s bandwidth is 400 MHz.

As the diagram shows, the module uses an LDMOS substrate with an LDMOS driver for the GaN PA. In addition, the module includes thermal management and an SiGe PA controller. Thermal management uses an internal temperature sensor. A circuit adjusts the PA’s gate bias voltage based on temperature. The bias control eliminates the need for a separate analog control IC, providing tighter monitoring and optimization of the PA’s performance.