EVM analysis for OFDM direct conversion transmitters

F. GREGORIO; J. E. COUSSEAU; S. WERNER; T. RIIHONEN; R. WICHMAN

IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

Lugar: New York; Año: 2013 vol. 62 p. 3443 - 3451

0018-9545

Low-cost orthogonal frequency-division multiplexing(OFDM) direct-conversion transceivers suffer from signal degradation through the impairments of the analog front end, e.g., due to in-phase and quadrature (IQ) imbalance, phase noise, and nonlinear power amplifier (PA) effects.This paper analyzes joint performance degradation due to these key transmitter imperfections. Error vector magnitude (EVM) is chosen as the figure of merit, which is motivated by its frequent use in the standards for specifying transmitter requirements. In particular, we derive closed-form EVM expressions for the challenging problem of wideband OFDM transmitter design and validate the analysis through simulations. Based onthe study, it is possible to conclude that EVM is governed by the memory effects associated with the PA and the reciprocal of the image rejection ratio (IRR), which is defined by the IQ modulator. We also demonstrated that intercarrier interference (ICI) due to the local oscillator phase noise shows an approximately frequency-flat response.