Switching characteristics of phase modulators

The influence of the p-i-n-diode switching transients on the performance of digital phase modulators is studied. To this end two models are introduced: a diode model which allows one to calculate the transient impedances, and a black-box model of a phase modulator which can be incorporated in network analysis programs in order to simulate system performance. Based on these models, guidlines are given for an optimum choice of various design parameters as for example the i-layer width of the p-i-n-diode, the switching-current ratio, the switching-current waveforms and the modulator bandwidth.