A highly integrated CMOS direct digital RF quadrature modulator

In English A highly integrated CMOS direct digital RF quadrature modulator, consisting of two 10-bit linear interpolation current steering digital-to-analog converters (DACs) and two Gilbert cell based mixers, is described. By employing linear interpolation, the attenuation of the DAC's image components is significantly increased, and the reconstruction filter is therefore eliminated. The DAC's differential current signals are directly sent to the mixer, which improves the linearity of the modulated RF signal. Measurement results on operations of 16 QAM and GSM are presented. This structure is suitable for system-on-chip (SOC) design