This paper describes a multi-purpose radar system suitable for applications with different requirements on dynamic range, resolution, and miniaturization degree. It utilizes a scalable sensor platform that includes a wideband 30.5-GHz voltage-controlled oscillator (VCO) as well as 61- and 122-GHz transceivers (TRXs) in a silicon-germanium BiCMOS technology. The proposed architecture enables the cascading of multiple TRXs and allows the implementation of MIMO radar systems in two different frequency bands by using a single VCO. The higher transmit output power of 11.5 dBm as well as receive gain of 24 dB make the 61-GHz TRX suitable for applications requiring a high dynamic range. The lower wavelength allows the integration of on-chip antennas in the 122-GHz TRX and enables, thus, a high miniaturization degree. The higher LO scaling factor makes the 122-GHz TRX also more attractive for high-resolution applications. A sweep bandwidth of 2.5 GHz generated by the VCO is scaled up to 10 GHz and results in a range resolution of 3 cm. The proposed TRXs are equipped with binary phase shift keying modulators as well as an I/Q receiver and can be utilized to build a flexible software-defined radar platform for range and distant-selective vibration sensors utilizing frequency-modulated continuous wave as well as pseudo-random noise radar techniques.