Abstract: A Quadrature Voltage Controlled Oscillator (Quad VCO) based on standard digital cells and delay cells, is adapted to generate two high-frequency output signals that are “in quadrature”, so they both oscillate with similar frequency while exhibiting a mutual phase offset of about 90 degrees, and a) the digital cells include a mix of digital circuits used for implementing standard flip-flop circuits and standard logic gates; and b) the delay cells include circuits accepting a logic signal at their input and outputting a time-delayed version of said input signal, with a time delay that may be varied by a control voltage analog signal that determines the cell delay.