Provided are a measurement circuit and method for serially merging single-ended signals to analyze them. To analyze two differential signals probed from a DUT, that is, DP and DM signals, the measurement circuit detects DP data from which its DC portion has been removed and DM data from which its DC portion has been removed, stores the two data signals in a memory, and then serially merges the two data signals stored in the memory without distorting them. The measurement circuit divides the serially merged signal at a predetermined period and overlaps the divided signals to generate eye diagram data and analysis data including crossover voltages, rising time, falling time and so on.