We are rounding up our Clock Jitter series by taking a look at what external factors can induce jitter in oscillators, and how they can be effectively compensated for. Continue reading
Continuous advances in high-speed communication and measurement systems require higher levels of performance from system clocks and references. Continue reading
In addition to this blog we keep a selection of longer form articles and whitepapers on our website. Continue reading
In a previous post we described Power Supply Rejection Ratio (PSRR) and discussed the ways it can impact an oscillators performance. In this update one of the ways we approach measuring PSRR on our devices. Continue reading
What is PSRR?
Power Supply Rejection Ratio or Power Supply Ripple Rejection (PSRR) is a measure of how well a circuit rejects noise, of various frequencies, injected at its voltage input. The ripple can be induced from a number of sources, such as a 50Hz/60Hz supply ripple, a switching ripple from a DC/DC converter, or a ripple due to the sharing of an input supply between different circuit blocks on the board. In the timing solutions world, when discussing PSRR we are typically referring to supply ripple.
Holdover is what happens when the primary timing reference goes away for some reason and the local oscillator is left to its own devices (for a fairly well maintained summary of the topic see the Wikipedia article Holdover in synchronization applications)
The question is: How much can you trust the local oscillator and for how long?