Ka-band Solid State Power Amplifier Developed

Output power is always a key of millimeter-wave systems. Compared with the electronic vacuum devices, solid-state power amplifiers have several advantages: small volume, light weight, low supply voltage, and long working life. Its disadvantage is it has small output power in millimeter wave band constitutionally.Aiming at the increasing requirement of solid-state power amplifiers in millimeter-wave systems, this thesis focuses on the key points in power combination techniques. The influences which caused by insertion loss , magnitude unbalance and phase unbalance which generated by power amplifiers are investigated through simulation method, the result shows that the combining efficiency is up to 90% when the difference in magnitude is 3dB and the difference in phase is 30°, and the insertion loss deteriorate the combining efficiency badly. The characteristics of three-port networks and four-port networks are compared and investigated through network analyzing method, to improve the three-port power dividing network, a four-port 3dB branch waveguide combiner is introduced into power combining circuit to be the power dividing network which makes all the ports matched and the isolation is up to 15dB at 30-40GHz band. The waveguide combiner is a unbalance structure, so the influences caused by magnitude and phase unbalance which generated by the branch waveguide combiner are also investigated through simulation method, the result shows that the phase unbalance has no influence on combining efficiency and magnitude unbalance has little influence on combining efficiency, the combining efficiency would be up to 97% if the magnitude unbalance were 3dB when the amplifiers are saturated. To improve the integration, a double-channel waveguide-microstrip probe transition structure is designed, the simulation return loss is up to 20dB. This structure and the 3dB branch waveguide combiner constitute a four channel power dividing network, the back-to-back insertion loss is less than 1.5dB at 30-40GHz band and be 0.5dB at center frequency. The assembly technologies at millimeter-wave band are introduced and a common rule of bonding-wire's influence to system performance is summarized through simulation method. A power combiner with AMMC-5040 is realized. At 33-37GHz band, the combining efficiency is up to 80%.The works presented in this thesis is valuable for referring in practical engineering.