A 1.5V direct digital synthesizer with tunable delta sigma modulator in 0.13 μm CMOS

In the new architecture presented in this paper, the signal band of the ΔΣ modulator is tuned according to the direct digital synthesizer (DDS) output frequency. We use a hardware efficient phase-to-sine amplitude converter in the DDS that approximates the first quadrant of the sine function with sixteen equal length piecewise-continuous second degree polynomial segments. The DDS is capable of frequency, phase, and quadrature amplitude modulation. The die area of the chip is 2.02 mm² (0.13 μm CMOS technology). The total power consumption is 138 mW at 1.5 V with output frequency of 63.33 MHz at a clock frequency of 200 MHz (D/A converter full-scale output current 11.5 mA).