Enhancing beneficial jitter using phase-shifted clock distribution

Abstract

Clock jitter is generally considered undesirable but recent publications have shown that it can actually improve the timing margin. This paper investigates the "beneficial jitter" effect and presents an accurate analytical model which is verified with HSPICE. Based on our model, a phase-shifted clock distribution technique is proposed to enhance the beneficial jitter effect. By having an optimal phase shift between the supply noise and the clock period, the timing margin can be improved by 2.5X to 15% of the clock period. The benefit of the proposed technique is equivalent to that of having a 5X larger decoupling capacitor.