Computer simulation and measurement of error vector magnitude (EVM) and adjacent-channel power ratio (ACPR) for digital wireless communication RF power amplifiers

Computer simulation and measurement of the error vector magnitude (EVM) and the adjacent channel power ratio (ACPR) of a 2.4 GHz MMIC power amplifier (PA) for digital wireless communications is presented. A computer simulation based on the π/4-DQPSK modulation with square-root raised cosine (SRRC) filter is established for this study. Using digital signal processing techniques and a time-domain approach, we can accurately predict the EVM and the ACPR related to the input power. The nonlinear effects of the MMIC PA are modeled as traditional nonlinearity parameters, such as 1-dB gain compression point or third-order intercept point IP3, by which the EVM and ACPR are simulated. A standard NADC modulated signal from a HP ESG-D signal generator is applied to the MMIC PA and the output signal analyzed by a HP 89410A vector signal analyzer. The measured results agree well with the simulation curves. This shows that the computer program by Matlab is useful to RF/microwave system engineers in the design of power amplifiers for digital wireless communications