LINC Digital Component Separator for multicarrier W-CDMA-signals

An implementation of a Digital-Component-Separator (DCS) for a LINC-system on a FPGA is presented. It employs a flexible image-reject-architecture for transmission of combined multicarrier W-CDMA signals and uses the phase-modulation method. Four Direct-Digital-Synthesizers (DDS) are employed as phase modulators, operating on a first low IF carrier between 0 to 1/4 of the sampling frequency. Image-reject-up conversion to 2 GHz is achieved with two additional I/Q-modulators. The sampling frequency can be chosen up to 32 times (122.88 MHz) the symbol rate of the W-CDMA chip rate of 3.84 Mbits/s. The system allows a flexible frequency assignment and spacing of one or two independent W-CDMA channels. The paper outlines how the envelope and phase information of two combined W-CDMA channels may be pre-calculated in real-time. This information may be used for the generation of two phase-modulated signals, which are then supplied to a single LINC-transmitter.