ROA-Brick Topology for Low-Skew Rotary Resonant Clock Network Design

Abstract

This paper presents a topology-based solution for a low-skew rotary oscillator array (ROA) clock distribution network design. An ROA-brick structure is proposed that limits the traveling wave oscillation to only two uniform ring rotation directions in the ROA-brick: all the rings in clockwise (CW) direction or all the rings in counter CW direction. An ROA built from the ROA-bricks has the following advantages: 1) similar to the ROA-brick, only two uniform ring rotation directions are feasible in the ROA; 2) the same phase tapping points of all the rings in the ROA are identifiable; and 3) these same phase tapping points of the ROA are independent from the two possible rotation directions. It is mathematically proved that the ROA-brick is the only ROA structure, which can limit the ring rotation direction combinations so as to guarantee the generation of same phase clock signals. The proposed brick-based ROA clock generation and distribution networks are designed for ISPD 10 clock benchmarks demonstrating the gigahertz operation with the low-skew clock generation and distributions through HSPICE.Index Terms-Clock distribution network design, resonant clock, synthesis.

Thermal and flicker phase noise analysis in rotary traveling‐wave oscillator

“…The variable "a(t)" in Equation (6) is the differential voltage amplitude and varies with time. Because it is constant in the steady-state oscillation, we can substitute da/dt = 0 in Equation (6) and solve the equation to extract V RTWO . The result is…”

“…As one of the newest wave‐based oscillators, rotary traveling‐wave oscillator (RTWO) has gained recent interest due to some of its abilities: operating at high frequencies, sustaining a traveling wave with low phase noise, providing clock distribution with low skew and low jitter, and providing multiple‐phase signals . The property of providing multiple‐phase signals from different positions of the RTWO is useful for obtaining precise in‐phase and quadrature‐phase RF signals for I/Q modulation.…”