2 GHz Bandwidth Predistortion Linearizer for Microwave Power Amplifiers at Ku-Band

Modern communication satellites carrying large numbers of signals require High PoWer Amplifiers (HPAs) which provide RF power with high linearity and high efficiency. Solid state power-amplifiers (SSPAs) and travelling-wave tube amplifiers (TWTAs) are the candidates for thiS application. Predistortidn linearizer circuits, are used to improve the performance of these aimplifier types. A 10.7 to 12.75 GHz predistortion linearizer is realized in coplanar waveguide tchnology with only three active elements, two Schottky diodes and one monolilthic microwave integrated circuit (MMIC) amplifier. This linearizer shows good capabilities for gain and phase adjustments: gain expansion of 5 dB and phase shift between 20 and 50 degrees can be obtained with this circuit over 2 GHz of bandwidth and about 10 - 12 dB input power dynamic range. Furtheron, the linearizer offers an input and output VSWR of better 1.4 : 1 over bandwidth. Low mass and size and increased reliability makes this linearizer suitable for satellite as well as for ground station applications.