Circuit for generating an output pulse string whose frequency is a linear combination of the frequencies of two independent input pulse strings

摘要

The invention relates to a circuit which is able to combine additively the frequencies of two input pulse strings. The need for additive combination of two frequencies often arises in communications systems, control systems and measurement systems and this need has hitherto been met in most cases with the aid of a mixer with downstream bandpass filtering. For this purpose, the proposed circuit uses a modified phase-locked loop (PLL) and therefore requires no bandpass filter. The proposed solution can be integrated apart from one or, at the most, two capacitors.