A Ku-Band 40 W Dual Output GaN Power Amplifier MMIC Integrated With a Novel Reliability Enhancement Circuit for Load Mismatch

The load mismatch reliability issue is a significant challenge in designing high-power amplifiers. This article presents a Ku-band single-input dual-output gallium nitride (GaN) high-power amplifier microwave monolithic integrated circuit (MMIC) integrated with a load-mismatched reliability enhancement circuit. Load-mismatched power detecting and automatic impedance reconfiguration techniques are demonstrated. In the load-mismatched power detecting technique, a novel buck circuit is proposed to cope with different load mismatch magnitude and phase variations; in the automatic impedance reconfiguration technique, a novel bandwidth broadening method is proposed by adding a series capacitor to the switch transistor. The reconfigured output matching network (OMN) increases the impedance at 15 and 16 GHz, reduces the peak output power and drain current, and lowers the junction temperature of the single-pole double-throw (SPDT) switch, resulting in enhanced load mismatch reliability with a response time of 40 nS. All active devices are fabricated using the GaN power amplifier and switch integration process. The measured output power of the MMIC is 46.1–47.0 dBm at 28 V operating voltage at 14–18 GHz frequency band, and the power-added efficiency (PAE) is 29.3%–35.2%. The MMIC’s size is $4.5\times 5.7$ mm2. Compared with the reported techniques, the proposed MMIC has higher output power and PAE, and it automatically triggers the reliability enhancement function after load mismatch without relying on external signals and has a faster response time.