For high-speed optical communication systems, timing jitter is a crucial parameter for switching operations between the data and control signal. This is especially the case for the demultiplexer. The effect of timing jitter becomes very important as the bit rate of the data signal increases beyond 100 Gb/s and it is, therefore, essential to quantify its effect. In this letter, the impact of gating timing jitter on a 160-Gb/s demultiplexer is investigated by using two pulse sources with different timing jitter properties. We also investigate the interplay between the control signal pulsewidth and timing jitter. The experiment shows that it is essential to minimize jitter in the 20-kHz to 10-MHz range. Furthermore, we show that the impact of timing jitter can be reduced if the control signal pulses are broader than data signal pulses.