Abstract: A variable frequency oscillator is disclosed wherein the magnitude of a signed digital input determines the output frequency. The variable oscillator includes a digital integrator circuit for performing a modulo 2.pi. digital integration of the input signal. The integrator circuit is connected to a digital quadrature circuit which converts the integrated input signal from its polar form into two digital control signals in the rectangular domain having a quadrature phase relationship. The control signals are utilized in analog form by their combination with a high frequency carrier and its quadrature phase to synthesize the desired output frequency in an analog embodiment. According to another embodiment the quadrature synthesis is provided by the digital combination of the control signals and the phased carrier components.