Abstract: Circuit for generating a spread spectrum clock (CGSSC) that employs a mechanism to modulate the input voltage (V_ctrl) to the VCO to achieve dithering. The CGSSC includes a voltage controller oscillator (VCO) that generates an output signal (F_out). The VCO includes an input coupled to a voltage control node for receiving a voltage signal and an output for generating a clock signal that has a frequency dependent on the received voltage signal. A VCO input voltage modulation mechanism (VIVMM) is coupled to the voltage control node (V_ctrl) for modulating or adjusting the voltage at the VCO input voltage node in a controlled manner to generate a spread spectrum clock.