A built-in self-test (BIST) architecture is proposed for voltage-controlled oscillators (VCO) operating at multi- gigahertz frequencies. By utilizing a frequency divider and a frequency-to-voltage converter (FVC), the output frequency and tuning range of the VCO can be extracted without external test instruments. The proposed BIST module is integrated with a wideband VCO as the DUT in a 0.18-mum CMOS process for demonstration. Within the tuning range of the VCO from 4.4 to 5.5 GHz, a frequency extraction error less than plusmn0.4% is achieved. The active area and the power consumption of the BIST module are 0.038 mm2 and 11 mW, respectively.