Quadrature modulator model with third-order non-linearities

A power-series based model for direct-conversion quadrature modulators with sinusoidal inputs is given in this paper. Starting from a linear approximation of different real-life non-idealities the proposed model has been further developed with inclusion of the second and third order power-series coefficients. Grouping of the resulting sinusoid terms as per output tone has been used to exclude model co-efficients which do not transmit to the frequency band of interest, and this simplified quadrature modulator model is compared with simulated results which have been extracted using a 65-nm CMOS quadrature modulator implementation.