Managing clock risks

Anyone can deliver wonderful things in the distant future. You, however, have to deliver on a schedule. Every risk your project takes endangers that schedule. Your complex system-on-a-chip may have just one or two clocks, or it may have a dozen. In most systems, every one of these clocks is derived from one or more phase-locked loops. Timing jitter from these PLLs shows up on every timing path in your design, and in every AC spec you promise to your customers. You owe your customers and your engineers the finest PLLs available.

What do your people think?

Ask your system architect if it’s useful to have a PLL vendor with a huge range of flexible, off-the-shelf PLLs. Does it matter if the vendor has a dedicated design team available both to help you design the simplest possible clocking scheme, and to design custom PLLs if your problem resists a simple clocking scheme? Consider for yourself the nature of the licensing terms, whether it obligates you to lingering royalties or special multiple-use pricing. Does the vendor need a test chip? Yours, perhaps? Ask your vendor qualification people if you can switch foundries without requalifying your PLL vendor. Such changes are only possible if the PLL vendor’s complete range of products are available to you on a broad range of processes from several foundries. Ask the person responsible for timing closure about the value of a very low-jitter clock source. Ask that person how much it matters if the PLL vendor has fully characterized their design. Ask that person if they even believe the performance specifications claimed by your current PLL vendor. Ask your bring-up team what it’s like to work with a prototype with an unreliable clock source that has to be fixed in a second spin of the chip. Does it help if the PLL works well even outside the specified frequency range, even in bad packaging, or in the presence of unexpected noise?

Choosing a PLL vendor

It does not have to take days or weeks to select a PLL provider. Talk to the best, first. That’s us. Your engineers can use our presale support to familiarize themselves with the clocking problems at hand while they evaluate our products. Check our references. Then you will be able to make an informed and quick decision about the quality level you need from your PLL provider. Many of our customers are willing to supply references. Maybe the reason is that no TCI PLL has ever failed a customer. Or maybe it’s because we are easy to work with. Find out for yourself. You will find that much of this site is open for you and your team to access right away. We do ask that you complete a Non-Disclosure Agreement (NDA) before we grant access to the detailed specifications of our designs. It is easy and fast. To download TCI’s standard Mutual Non-Disclosure Agreement, please go to the Licensing page. At any time, you should feel free to call us with your questions.