an improved circuit for pulsed biphase modulation of a sine wave carrier having the same frequency as the clock frequency selects carrier phase deviations from static phase shift circuits by means of multiple bilateral semiconductor switches which are controlled by coded pulses generated in a digital processing cirucit receiving nrz digital data . the switches are controlled by the pulses to disconnect the carrier and to connect the phase deviations to the output at the start and at the middle of a cycle of the carrier frequency .