X Band Gaas Monolithic Power Amplifier

This dissertation presents a brief introduction on microwave monolithic integrated circuits (MMIC). The content mainly include:history and current situation of MMICs, physical characters of gallium arsenide (GaAs), basic structures and operating principles of high electron mobility transistor (HEMT), device modeling and parameter extractation, fabrication process, major index of microwave transistor power amplifier.An8.5GHz-12.5GHz GaAs monolithic power amplifier (PA) was designed, fabricated and texted based on these foundations. Utilizing3-stage common-source cascade circuit topology, the PA was fabricated using a GaAs pHEMT power process in CETC-13. The amplifier achieved over30dBm1-dB compression point (P-1) output power, about25dB small signal gain and more than28.3%power-added efficiency (PAE) at the DC biasing point of Vds=8V, Vgs=-0.7V. Meanwhile, the input/output voltage standing-wave ratio (VSWR) are both less than1.9.The sizes of transistors, DC biasing points and circuit topology were chosen according to the design targets of PA such as gain, output power, PAE, linearity, etc. Load-pull simulation results of the HEMT large signal model are also important reference. In order to obtain high linearity,2-Tone load-pull simulation was introduced to look for the optimum impedance matching point. Classic method was employed to design the biasing circuits and matching circuits. The measured IM3was less than-35dBc when the2-Tone total output power was23dBm. The chip size is4.0×2.4mm2.Further more, the differences between measured result and simulated result are analyzed. The effect of the thick metal of the microstrip line is the main reason that caused the difference.