In high-speed differential interconnects on printed circuit boards, signal integrity (SI) issues arise when neglecting the inherent low-pass characteristic and ubiquitous presence of common-mode noise. This work proposes a novel open-circuited stub equalizer with integrated common-mode filter in order to compensate for the low-pass characteristic while simultaneously suppressing the transmission of unwanted common-mode noise to the receiver. A theoretical analysis of the open-circuited stub equalizer is conducted, and suitable approximations are derived to facilitate equalizer synthesis. Experimental validation is provided by a test structure consisting of a 20 cm microstrip serpentine delay line for which a 4 GHz equalizer is designed. Frequency-domain measurements show a 1-dB bandwidth up to 3.97 GHz with a passband ripple of 0.38 dB for the differential mode and a significant reduction in transmission for the common mode. The resulting SI enhancement increases the possible data rate from 6 Gbps to 20 Gbps using a PAM-4 (pulse amplitude modulation 4-level) modulation scheme.
Bridging the AC Non-Equilibrium Green’s Function Formalism and Transmission Line Models for the Analysis of Nanointerconnects
The unfavorable scaling of Cu interconnects at nanoscale dimensions has prompted the search for alternative materials. To model electron transport in these novel nanointerconnects, both