Design of 60W Internal-matching 3.5GHz/5.3GHz Dual-frequency Amplifier for S-L Band

Based on the $0.35 \mu \mathrm{~m}$ process platform of the Nanjing Institute of Electronic Devices, a 14.4 mm GaN HETMT was used to design a $3.5 \mathrm{GHz} / 5.3 \mathrm{GHz}$ dual-frequency internal matching power amplifier. The output matching circuit employs a low-pass L-C matching network, where two independent complex impedances are transformed into a pair of conjugate impedances. By utilizing a transmission line, the conjugate impedances are then transformed into the same real impedance, eliminating the imaginary component. Finally, an l-C matching network is used to match the impedance to $50 \Omega$. The input matching utilizes broadband matching through a series inductance and an L-C-L matching network, which transforms the output complex impedance into a larger real impedance. This is then matched to $50 \Omega$ using two sections of a quarterwavelength transmission line. The amplifier achieves a saturated gain greater than 14.8 dB and a drain efficiency exceeding $62 \%$ at the dual frequencies. The device is packaged in a shell with dimensions of $\mathbf{2 2. 8 m m} \boldsymbol{*} \mathbf{~ 2 1. 3 m m}$.