An analytical maximum toggle frequency expression and its application to optimizing high-speed ECL frequency dividers

A novel method is used to analyze static and regenerative frequency dividers by relating their performance to that of the constituent EXCLUSIVE-OR (XOR) gates. It is found that the behavior of the propagation delay of XOR gates is quite linear, and this allows the derivation of a propagation delay expression for XOR gates using a sensitivity analysis. The validity of the expression is checked by comparison with SPICE simulations and with results from the literature, and agreement to 10% is obtained. It has been found that this expression can be used to accurately predict the maximum toggle frequency of frequency dividers. Using this expression, it has also been verified that the maximum toggle frequency of regenerative frequency dividers is about twice as high as that of static frequency dividers. In order to optimize frequency dividers, figures of merit for frequency dividers realized in silicon and AlGaAs-GaAs technologies are proposed.<
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