A Differential Pair-Based Direct Digital Synthesizer MMIC With 16.8-GHz Clock and 488-mW Power Consumption

This paper presents a low-power, high-speed direct digital synthesizer monolithic microwave integrated circuit in a SiGe bipolar technology with 8-bit phase and 6-bit amplitude resolution. The phase-to-amplitude mapping circuit is implemented as a differential pair in saturation. The use of a modern SiGe bipolar technology enables both a low power consumption of 488 mW at a 3.3-V supply and a high clock frequency of 16.8 GHz; here, the maximum output frequency is 8.3344 GHz and the frequency resolution is 65.625 MHz. A spurious-free dynamic range (SFDR) between 47-20 dBc is achieved. First Nyquist zone SFDR, narrowband SFDR, and frequency-modulation measurements of the signal are shown and discussed. The chip is fabricated in a 0.35-??m 200-GHz f_T SiGe bipolar technology and occupies only 1128 ?? 1028 ??m². The chip is mounted on a printed circuit board for measurement.