Look-Up Table Based Low Power Rotary Traveling Wave Oscillator Design Considering the Skin Effect

Rotary clocking is a low-power technology alternative for multi-GHz clock generation and distribution. In this paper, the power efficiency of the rotary traveling wave oscillator is analyzed at the predicted multi-GHz frequencies, where the skin effect becomes dominant. The filament model is applied to investigate the transmission line resistance and inductance with the skin effect for analyzing the transmission line power consumption in the rotary traveling wave oscillator (RTWO). A 3D full-wave simulation model is implemented, the result of which shows good agreement with the calculation results from the filament model. A lumped RLC transmission line model is built to facilitate the HSPICE simulation in order to predict the power consumption of a RTWO transmission line in high frequencies. The design parameters of RTWO perimeter and inverter size are analyzed for optimizing the power consumption of the transmission line. Simulation results show that the transmission line power consumption at 20 GHz can be as low as 29.6% of the power consumption at 3 GHz by selectively choosing the design parameters (though the driving capability of the RTWO is a trade-off for power consumption). Based on the simulation results, a low power design table for the RTWO is provided. Finally, an RTWO array is built using the optimized design parameters. It is shown that when the skin effect is considered (increasing the accuracy of the simulation results), the RTWO array still saves up to 68.6% power compared to a traditional clock tree.