Ultra-Wideband Signal Source Tuneable From 86 GHz to 142 GHz in SiGe Technology

The range of applications for radar sensors has diversified considerably in the last time. In addition to military and automotive applications, radar systems are also used in industrial and medical applications. Depending on the application, the bandwidth has a decisive influence on the detection of objects.Often, a tunable capacitance (varactor) is used for oscillators in the millimeter wave and THz range to vary the oscillation frequency. However, depending on the technology used, this approach is limited in its tuning range.This paper presents an approach using two simultaneously tuned VCOs and a mixer. Although both VCOs are based on tuning a varactor diode, the tuning range can be increased considerably by tuning the VCOs in opposite directions. Both VCO signals are fed into a mixer, whose output generates an ultra-wideband signal. For realization, we use the B11HFC technology and two VCOs at the center frequencies of 52 GHz and 104 GHz, respectively. At the output of the signal generator, a signal with 114 GHz center frequency and a tuning range of 56 GHz (49% rel.) is generated.