This paper presents the study and simulation of IQ impairments influence in a Radio Frequency (RF) transmitter architecture. The context is the transmission of OFDM signals such as IEEE 802.11a. The transmitter architecture is considered in two cases : a classical reference case such as homodyne for example and a linearised case, based on the EER (Envelope Elimination and Restoration) or polar architecture. EER was considered here because it provides an interesting high efficiency multi-standard transmitter architecture solution for actual digital communications high data rate standards. Equations are derived in the case of emission and reception of an OFDM signal with N sub-carriers and simulations are performed to confirm the theoretical results. Conclusions are given concerning the impact of IQ impairments on the Error Vector Magnitude (EVM) for both architecture cases. Copyright (c) 2008 Praise Worthy Prize S.r.l - All rights reserved.