Improved Target Impedance Concept With Jitter Specification

In this article, an improved target impedance concept directly correlating circuit output jitter with power distribution network (PDN) R-L-C parameters is proposed. A systematic procedure to develop the target impedance curves is formulated and developed for common CMOS buffer circuits. The relationship between output jitter and PDN R-L-C parameters is analytically derived by evaluating the time domain voltage ripple to jitter transfer relationship along with the relationship between time domain voltage ripple and PDN R-L-C parameters. Given the transient integrated circuit switching current and the jitter specification, multiple target impedance curves can be defined for a specific circuit. The jitter and PDN R-L-C analytical correlations are validated through HSPICE simulation. The application of the proposed target impedance concept with jitter specification is also demonstrated via simulation.