A high-speed SiGe BiCMOS direct digital frequency synthesizer（DDS）is presented.The design integrates a high-speed digital DDS core,a high-speed differential current-steering mode 10-bit D/A converter,a serial/parallel interface,and clock control logic.The DDS design is processed in 0.35μm SiGe BiCMOS standard process technology and worked at 1 GHz system frequency.The measured results show that the DDS is capable of generating a frequency-agile analog output sine wave up to 400＋MHz.
