CROA: Design and Analysis of the Custom Rotary Oscillatory Array

Rotary clocking is a resonant clocking technology for clock network design and distribution in high performance digital VLSI circuits. Rotary clocking technology offers an attractive alternative to the conventional clocking with high frequency clock signal generation at a low power dissipation rate. Traditionally, rotary clocking has been implemented using a regular array (grid) topology called rotary oscillatory arrays (ROA). In this paper, a custom rotary oscillatory array (CROA) topology is proposed for the generation and distribution of rotary clocking. The issues related to timing closure are addressed and the simulation-based analysis of the custom rotary rings is presented. The CROA design methodology is tested on the IBM R1-R5 benchmark circuits. Compared to the traditional ROA, custom ROA results in 39.25% of tapping wirelength savings. The parasitic effects due to the customization of the topology - computed with partial element equivalent circuit (PEEC) analysis - are incorporated and the CROA topologies are simulated in SPICE. The simulation results show that, with additional parasitics due to the topological factors, the resultant clock frequency is observed to be 8.79% slower (assuming the tapping wirelength remains the same) than the expected frequency of operation without considering the topological factors.