Comparing Linearity Measurements in a GaN Ka-Band Satcom Power Amplifier

Most modern Ka-Band Satellite Communication systems rely on solid state power amplifiers for their transmitters last stage. This item gives the transmitting signal the final power boost before being sent to the antenna, and its parameters are critical for the overall performance of the whole system. The power amplifier’s output power, linearity and efficiency are important variables to be considered for the final system design, which is normally based on wide-bandgap semiconductors like GaAs or GaN.GaN based amplifiers are becoming more important due to their superior power density and power efficiency, which allows the manufacturing of smaller and more efficient transmitters.

There are different methods to characterize the non-linearities of a given power amplifier. In this Tech Brief we focus on the Adjacent Channel Power Ratio (ACPR), that measures the amplifier behavior under a specific modulated input signal, giving a direct and clear indication of amplifier performance for a given application, and we compare this with classical RF parameters of the amplifier such us P1dB, Psat and OIP3.