The solid state power amplifier applications are in airborne radars, Missiles and communication systems. It offers a peak power output of 400 watts. We designed the SSPA using Ghorbani model. Due to the Non Linearity nature of SSPA, both power and spectral efficiency of the signal is reduced. To improve signal power and spectral efficiency of a 16QAM modulated signal, we linearize SSPA by Predistortion Technique. Using this method the ACPR of the signal can be improved by 20db.