Abstract: Apparatus for phase keying in frequency and phase voltage controlled oscillator with an incoming signal having a T period phase coded of the biphase PCM or PSK type.The apparatus comprises a circuit loop for phase controlling the oscillator with logic circuitry and first and second conductive paths. Each of the first and second conductive paths have integrators. The integration time of the first and second integrators is equal to the period T of the incoming signal. The limits of integration of the first integrator are - T/8 and + 7T/8 and the limits of integration of the second integrator are + T/8 and + 9T/8. A delay element is disposed between the logic circuitry and the second conductive path introducing retardation time of T/4.