Fast and accurate ramp generation with a PLL-stabilized 24-GHz SiGe VCO for FMCW and FSCW applications

In Microwave sensor systems the application of linear frequency modulation schemes as well as frequency stepping is commonly used. In this paper we describe the generation of fast and highly accurate frequency ramps by means of a fractional-N-PLL stabilized integrated 24-GHz voltage controlled SiGe oscillator, which are a prerequisite for high achievable measurement accuracies. Linearity measurements with phase evaluation on fabricated devices have shown an RF-phase deviation of less than 1.5 rad for a linear frequency sweep with a bandwidth of 250 MHz at 24.5 GHz and a sweep duration of 250 /spl mu/s.