US Patent 7421263 Circuit for reducing second order intermodulation

A circuit for calibrating a second order intercept point (IP2) and for reducing second order intermodulation (IM2) includes a common mode feedback circuit and a load impedance operatively connected between first and second output terminals of a mixer in a direct conversion receiver. The common mode feedback circuit reduces second order intermodulation of the mixer by detecting an output voltage of the mixer and adjusting a gain of the mixer. The IP2 is controlled by controlling the gain of the common mode feedback circuit. The second order intermodulation (IM2) may be reduced and the linearity of a device may be enhanced.