Large-shift constant-amplitude phase modulators

This article presents the method of realization of phase modulators characterized by the constant amplitude of the modulated signal and by the linear dependence of its phase shift in a large range on the input modulation signal. This is achieved by appropriate modulation signal processing in the base band. The inherent nonlinearity stemming from imperfect processing has been analyzed through the computer simulations of various devices with either analog or digital processing. Only the number of bits in one digital sample of the input modulation signal limits the maximum phase deviation achievable in the device with digital processing. An example shows how to get a phase deviation of /spl plusmn/16/spl pi/ through 12-bit quantization of the input voltage, with the inherent nonlinearity better than 1% in the whole range, and better than 0.01% in 95% of the whole range.