Ultra low noise signal synthesis for the use in a FMCW MIMO radar system

A great number of spatially distributed transceiver chips within multiple-input multiple-output radar systems make the reference signal synthesis as well as its distribution to an emerging topic. Therefore, we introduce a synthesizer based on the concept of fractional-N division which is able to provide a linear frequency ramp around 200 MHz. Furthermore, an ultra wideband phase-locked loop (PLL) is presented using this synthesizer and featuring a bandwidth of 22 GHz centred around 85 GHz. For stabilizing the PLL over the complete bandwidth a passive auxiliary circuit has been developed. The system achieves a phase noise below -78 dBc/Hz at 10kHz offset over its complete bandwidth.