The aim of this paper is to present the design and measurements of a Ku-band class AB power amplifier. This two stage amplifier, designed by ALCATEL and manufactured by THOMSON foundry service with HP07 process, works between 10.7 et 12.75 GHz. 11 dB gain is obtained with 33 dBm output power and a power added efficiency better than 27 % at 11.75 GHz.