n-linear impedance characteristics of VO2 offer solutions to highly sensitive radio-frequency (RF), millimeterwave (mm-wave), and terahertz (THz) detectors. We demonstrate high-speed broadband sensibility of miniaturized VO2 switches by utilizing the nonlinearity close to the abrupt insulator-to-metal transition (IMT). We apply an intensity modulated sub-THz signal to the 2-terminal devices inside a coplanar waveguide (CPW) and detect the down-mixed component at the intermediate frequency (IF). The maximum output IF power selectivity over noise reaches 45 dB with a-3 dB bandwidth of 12 GHz. Its responsivity to subTHz radiation and high-speed switching makes our design a potential detector for a wide range of high-data-rate wireless applications.