Solutions Research On Pcb Signal Quality Improvement Of High Speed Circuits

In the electronic system of much higher edge rates, higher density, higher power, lower supply voltages and larger transient currents, as the simultaneous switching noise(SSN) derived from high-speed transient current coupling to and spreading in the waveguide consisted of power and ground planes in the system’s power distribution network(PDN), the resonant modes between the two planes are excited. And this will cause power integrity(PI), and finally, severe signal integrity(SI) problems and electro-magnetic interference(EMI) issues. All of those can deteriorate the signal quality, even take the system away from its’ work. Power integrity, especially the suppression of plane resonance and SSN, has become the key point of improving the signal quality in high-speed digital circuit designs.Based on the status analysis of the power integrity and the planar electromagnetic band gap(EBG) structure’s features of plane resonance suppression and SSN elimination, the solutions of high-speed PCB signal quality improvement are proposed. The solutions firstly follows the typical signal integrity principles, then a new planar EBG structure is designed to suppress the plane resonance and SSN with the purpose of good power integrity, and finally, acceptable signal quality. The contents and achievements of the work are mainly listed as follows:1) Based on the "United Cells Method", a novel planar EBG structure is proposed by integrating two different kinds of bridges in the unit cell. Simulations and measurements are performed to verify the high performance both in plane resonance suppression and SSN elimination.2) Considering the signal quality deterioration arising from EBG structure, a policy with locally topology and keeping the return paths continuous is used to improve the signal integrity. Simulations and measurements are performed to validate the outstanding performance of the structure both in signal integrity as well as in simultaneous switching noise suppression. 3) The whole solutions for the improvement of the PCB signal quality is summarized. And the validation of the whole solutions is verified in practice.