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Iterative generation of sine and cosine signal by finite word length
Štursa, Jarmil
The iterative procedure of sine/cosine signal generation operates without the need of any ROM table. A special attention is given to the correct determination of initial conditions of the iteration process and to finite word length of some system factors. The program environment Matlab is used for the simulation of this process. The level of normalized errors of iteratively generated sine and cosine signal is investigated.
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Frequency synthesizers with sigma-delta modulation
Kroupa, Věnceslav František ; Štursa, Jarmil
We shall discus basic parameters of the steering signal. This signal is built in the sigma-delta modulator and controls pulse removing in the PLL frequency synthesizer. We shall investigate the dependence of these parameters on sigma-delta modulator order and give spurious phase spectrum of the fractional-N synthesizer with a low-pass filter of high degree.
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Frequency stability of fractional-N synthesizers
Kroupa, Věnceslav František ; Štursa, Jarmil
The spectral properties of the PLL frequency synthesizer operating in the fractional-N mode are investigated. This operation is based on the swallowing of pulses in the feedback path of the PLL. The pulse swallower is controlled by the steering signal which is generated by the network DDFS operating as a ä-delta modulator of a given order. The influence of the modulator order on phase spectrum of the steering signal is shown.
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Phase locked loops (PPL) design
Kroupa, Věnceslav František ; Štursa, Jarmil
The sampled and higher order systems are discussed and means for stability checking, with the computer simulation of the Bode plots, are mentioned. It is shown that computer plotting of the PLL transfer function H(s) and 1-H(s), with the assistance of the open loop gain G(s), provides many information influence about noise of different noise sources; i.e., noise of the reference oscillator, of the voltage controlled oscillator, of the phase detector and of inevitable filters.
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