An overview of 110 GHz and above solid-state integrated circuit power amplifiers and circuit topology is presented based on the latest device technologies in the past several years. The frequency, process, the maximum output power(Psat), the compression gain, small signal gain, gain of 1 dB compression point(P-1), power added efficiency(PAE), bandwidth of those amplifiers/power amplifiers are summarized. The circuit topologies of those amplifiers/power amplifiers and their applications in terahertz regime are discussed. The development trends of future solid-state transistor are expected according to ITRS literatures. The future technologies of integrating terahertz solid-state power amplifiers into terahertz digital-analog systems are discussed.