A compact antenna aperture tuner with high voltage enhancement-mode p-GaN HEMT switch

Abstract A compact antenna aperture tuner for an inverted-F antenna is presented using a high-voltage enhancement-mode p-GaN gate high electron mobility transistor (HEMT) RF switch with a gate length of 0.5 µm. The proposed design achieves a breakdown voltage of 100 V for a single p-GaN HEMT switch, enabling the replacement of conventional stacked high-voltage RF metal-oxide-semiconductor field effect transistor (MOSFET) configurations. A 4-bit switched-capacitor network based on p-GaN HEMT devices is employed to cover the n77 (3.3–3.8 GHz) cellular frequency band. Measured results show that a return loss exceeding 6 dB is obtained at the antenna feed point over more than 90% of the target frequency range. Under a continuous wave of 34 dBm, the measured reflected second- and third-order harmonics (H2 and H3) are −56 and −75 dBm, respectively. These results demonstrate the feasibility of p-GaN HEMT-based RF switches for compact and high-voltage antenna tuning applications.