A 0.8 /spl mu/m CMOS 350 MHz quadrature direct digital frequency synthesizer with integrated D/A converters

This quadrature DDFS calculates sine and cosine values with a tuning resolution below 1 Hz, by only using an 8 word ROM and interpolation. Two internal 8-bit differential D/A converters generate the four-phase analog output signal. A spurious free dynamic range of 50 dB for low frequencies and 30 dB near Nyquist is achieved.