IQ imbalance (original) (raw)

IQ imbalance is a performance-limiting issue in the design of a class of radio receivers known as direct conversion receivers. These translate the received radio frequency (RF, or pass-band) signal directly from the carrier frequency to baseband using a single mixing stage. Direct conversion receivers contain a local oscillator (LO) which generates both a sine wave at and a copy delayed by 90°. These are individually mixed with the RF signal, producing what are known respectively as the in-phase and quadrature signals, labelled and .