C/Ka Concurrent Dual-Band GaN MMIC Based on Shorted Quarter-Wavelength Line Topology

This paper presents a novel design method for a dual-band power amplifier (PA) with widely-spaced frequency bands, suitable for concurrent sub-6 GHz and millimeter-wave 5G band operation. The approach de-couples the design of the high- and low-frequency impedance matching networks, so that the high-frequency matching network can be fully designed before the low-frequency path is added. The circuit architecture includes a built-in bias structure for the high-frequency band so that a separate broadband or multiband bias network is avoided. This design process is first described theoretically, and a detailed design example of a C/Ka concurrent dual-band MMIC using quarter-wavelength lines implemented in a 150 nm GaN process is described. The MMIC is measured in CW with 32.5 dBm and 33% peak power and PAE in C band and 31 dBm and 24% peak power and PAE in Ka-band. Measurements with 100-MHz LTE-like modulated signals are also shown, including both individual and concurrent operation of the two bands.