Estimation of Characterization in MMIC Nonlinear Power Amplifier for OFDM Signal

This paper describes a theoretical approach to predict the error vector magnitude (EVM) performance of an uncoded orthogonal frequency-division multiplexing (OFDM) portable system in the presence of nonlinear distortion caused by power amplifiers. In the theoretical framework, it is shown that the EVM model can be described by means of autocorrelation of in-band uncorrelated distortion noise introduced by the AM/AM and AM/PM of nonlinear function and common complex gain. The advantage of the proposed stochastic method lies in the accurate prediction of performance of nonlinear devices without a demodulation of the received OFDM signals. For the experimental validation, we use a 1024(2¹⁰) IFFT-OFDM signal based on the 802.16e system, a 9.7dB peak to average power ratio (PAPR) at 0.001% CCDF, a 10MHz overall occupation bandwidth and 8.64MHz of effective bandwidth, and an EVM value of 64-QAM modulated signals through the fabricated HBT MMIC power amplifier for 2.3~2.4GHz frequency is derived by the proposed method and compared with the measurement results. The results are applicable to good agreement of performance of nonlinear devices