New Behavioral Models Facilitate Fast and Accurate Simulation of Sigma-delta Fractional-n Synthesizers Using Ansoft Designertm
نویسندگان
چکیده
AND JEFFREY L. CUTCHER Motorola Inc. Plantation, FL Fractional-N synthesizers are highly desirable in communication systems because of their high frequency resolution output. This resolution is made possible by dithering the divide value using the output of a sigma-delta modulator. A typical sigma-delta fractional-N frequency synthesizer is shown in Figure 1. The tri-state phase frequency detector (PFD) outputs an error signal in the form of up or down pulses proportional to the phase error between the reference and divider signals. This error signal is then used to generate corresponding positive or negative current pulses by NEW BEHAVIORAL MODELS FACILITATE FAST AND ACCURATE SIMULATION OF SIGMA-DELTA FRACTIONAL-N SYNTHESIZERS USING ANSOFT DESIGNERTM
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