A serializer device is used for generation, from a parallel digital signal, of a clock signal or a serial binary data signal having a pre-determined amount of jitter. A binary number having consecutive groups of ones and zeroes, when serialized by the serializer device, produces a clock signal. By varying the number of ones and zeroes on the binary number, a pre-determined amount of jitter can be generated. Use of sigma-delta modulation in combination with a phase-locked loop circuitry allows one to obtain a smoothly varying jitter of the output signal.