Disclosed is a tuned circuit tuned to an input signal having a predetermined radio frequency, the tuned circuit comprising a tank circuit having a loaded ring oscillator circuit with a resonant frequency corresponding to said radio frequency. The tank circuit is configured for a predetermined frequency that the tuned circuit is designed for. In the case wherein the tuned circuit is in CMOS 0.18 .mu.m technology, the tuned circuit is configured for a frequency of up to 7 GHz. The tank circuit may be in the form of an integrated circuit having a size of not more than 200 .mu.m by 200 .mu.m. The tank circuit may form part of a low-noise amplifier or part of a mixer.