How to Make High Accuracy EVM Measurements for Power Amplifiers Using the Keysight Vector Network Analyzers
Application Notes
Nonlinearity Evaluation of a Power Amplifier
In wireless communication systems, the power amplifier (PA) occupies the last stage of the transmission chain to supply required RF power to antennas, as Figure 1 illustrates. The PA plays an important role in determining the quality of the communication service with respect to signal quality and battery life.
The PA is also the most significant contributor to the quality of the RF chain in communication systems. Linearity is critically important in systems with high peak-to-average-power (PAPR) signals, as in modern wireless standards that use orthogonal frequency-division multiplexing (OFDM) for the digital modulation scheme. The nonlinear response of the RF chain directly impacts error in the demodulation, leading to poor bit error rate. Additionally, nonlinearity can create spectral regrowth, causing interference in other bands, so maintaining the linearity of the RF chain is crucial for the quality of wireless communication.