A direct digital synthesis based chirp radar transmitter in 0.13 µm SiGe technology

CMOS-integrated biosensor circuits and systems : FMCW radar sensor for noncontact multimodal vital signs monitoring and coherent photoacoustic sensor for non-invasive in vivo sensing and imaging

“…To generate fast chirp signal with high linearity, a DDS is typically adopted considering its open-loop nature for fast response. However, it normally works at low frequency from several tens to several hundred megahertz (MHz) with narrowband chirp for enabling the low power consumption [94], [95]. Therefore, the output frequency and bandwidth of DDS are multiplied by using a PLL-based chirp synthesizer converting it into the RF frequency range.…”