Design of 35-dB 0.03-to-2.7 GHz Two-Stage Broadband Power Amplifier With 37.2 dBm P sat Using Modular Technology

This paper presents a modular technology for two-stage broadband power amplifier (PA) design. The proposed method focuses on separately realizing two stage’s flat gain characteristics, thus providing the entire circuit’s required flatness over broad bandwidth. The power stage employs stacked structure to provide enough power and confine the output impedance around $50~\Omega $ , while the driver stage’s periphery is selected to achieve impedance transformation demanded by modularization. The elaborate requirements for input and inter-stage matching networks (MNs) are repeatable which can be synthesized by real frequency technique (RFT), shortening the design time of broadband MNs. The modular approach can also be transferred to the implementation of other broadband PAs. This novel technology was verified using $0.25~\mu \text{m}$ GaAs PHEMT process. The fabricated two-stage broadband PA obtains a small-signal gain higher than 35.0 dB and saturated output power of 37.2± 1.6 dBm from 30 MHz to 2.7 GHz, with a peak power added efficiency (PAE) of 46.2% at 500 MHz. To our knowledge, this is the highest gain and output power in GaAs broadband amplifier below 2.7 GHz.