Study on the output characteristics of a D flip-flop differential mixer

The output characteristics of a D flip-flop differential mixer were studied in theory and experiments. Its output period was variable though two input frequencies were invariable. There were two types of period, longer and shorter; their difference is one clock period. The output has only one type of period or the shorter and longer periods arrange by turns in some special cases. Shorter period is not in succession when longer period is and vice versa. The measurement data array is obtained by continuous counting the number of time standard within each cycle (sub-gate) of the D flip-flop mixer output. By selecting valid data corresponding to the each cycle starting at the first non-succession period and stopping before the last same type non-succession period and calculating them, the frequency of the unknown signal can be obtained with high resolution. The research results are very useful to measure resonant transducer output signals for high resolution.