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Fishing for Signal Integrity
SerDes Tuning Basics
Pieter has been a fisherman all his life. When he was a boy, he would spend every spare moment at the pier with his grampa’s old fishing rig, catching whatever would wander near the dock, all the while watching the fishing fleet leave and return under the bridge that spanned the entrance to the small harbor. He never liked cleaning the fish, however, so he would catch and release them, returning home with wildly exaggerated stories of the giant fish he had landed and then returned. Since no one but Pieter ever saw those fish, and since he never bothered to actually weigh or measure them, his exaggerated claims gradually became the truth - to him, at least.
Karl was Pieter’s older brother. Karl never saw the sense in Pieter’s passion for fishing. He rolled his eyes every day when his younger sibling would return spinning his obviously too-tall tales of conquests at the pier. Karl was practical-minded. He became a businessman – a distributor of fresh seafood products. When his younger brother Pieter bought a fishing boat and set out to fish for a living, Karl would buy all the fish his brother could provide. In order to protect his brother’s pride, he would normally credit him for almost double the weight he brought in, making the difference up by paying him a lower price per pound.
Karl was applying equalization on the receive end of the fish transfer from his brother. Karl knew the catch would come in with a lower actual weight than Pieter claimed, so he would “equalize” up to the weight his brother believed was appropriate for his day’s work. [more]
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