Signal Integrity

Power-aware Signal Integrity and EMI/EMC On High-speed Digital Chip-to-Chip Links

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Happy 177th Birthday, James Clerk Maxwell

Posted June 12th, 2008 · 2 Comments · History

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James Clerk Maxwell

James Clerk Maxwell at University of Cambridge with one of his colour wheels

James Clerk Maxwell was born June 13th, 1831 in Edinburgh, Scotland, UK. He synthesized previously unrelated observations, experiments, and equations of electricity, magnetism, and optics into a consistent theory and set of equations—Maxwell’s equations—demonstrating that electricity, magnetism and even light are all manifestations of the electromagnetic field.

Maxwell’s work has stood the test of time. Maxwell’s equations are consistent with the Lorentz transformation, and inspired Einstein’s special relativity. In this view, magnetism is not a separate field, but the simply the electric field with space-time distortion from charged bodies in relative motion. If the electric field is interpreted as the probability of observing a photon, the equations are consistent with quantum mechanics (quantum electrodynamics). QED has been extended to cover the weak nuclear force (responsible for beta decay) in the electroweak theory. Thus extended, the theory encompasses all physical phenomena except gravity and the strong nuclear force (quarks and gluons and such). The bottom line is that you can take the solutions to the bank: unlike SPICE, there are no approximations.

EM solvers are now a standard signal integrity analysis tool. Although the equations are computationally expensive to solve, the results accurately reflect the distributed nature of multigigabit per second serial links, where the wavelength of the highest frequency component is shorter than the physical size of the backplane. This is in contrast to nodal solvers like SPICE, which use a lumped element approximation, and which ignore crosstalk due to magnetic induction in conductor loops (curl(E) = -dB/dt).

Thank you, James Clerk Maxwell!

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