SDR-based digital IF for multi-band W-CDMA transceiver

This paper discusses the implementation of multi-band digital IF for W-CDMA transceiver. The implemented module in hardware is majorly composed of wideband ADC/DAC and FPGA, and the software is coded by VHDL. At transmitter, digital filter is constructed via cascading a series of decimation and interpolation filters, and in order to upconvert the multi-band baseband channels simultaneously, two-stage digital complex quadrature modulation (DCQM) is utilized. Relevant numerically controlled oscillator (NCO) to up- and down-conversion is designed in a form of LUT having samples associated with 1/4 period of sampled sinusoidal. At receiver, to avoid the usage of SAW filter, the high performance digital filter is implemented subject to satisfying band rejection ratio prescribed in blocker and adjacent channel specification. This paper provides the performance of the implemented digital IF module via showing the results measured from the measurement instruments. Moreover, computer simulations are conducted simultaneously to confirm its validity.