A Glitch-free Clock Multiplexer for Non-Continuously Running Clocks

Modern system-on-chips often integrate blocks, which need to be triggered by two or more clock sources depending on the circuit state. Glitchfree clock multiplexers are introduced to such systems for selecting the demanded clock. One specific problem of state-of-the-art solutions is that they need running clocks to perform the switching from one to another source. In this paper, a new clock multiplexer is presented, which overcomes this limitation and enables switching the clock, even if the clock stops running before switching has been performed. The applicability of the multiplexer has been proven in silicon by integrating it into a radhard 1.6-2.5 Gbps SERDES for space applications.