UC Santa Barbara

This work presents a novel CMOS behavior of self stabilization of ring oscillators using collective dynamics. It shows that phase error correction can occur in ring oscillators over multiple cycles without an external reference via the collective dynamics of pulses. In time domain this shows up as timing stability improvement in oscillators. Different timing stability metrics were analyzed to determine the correct methodology to analyze this stability improvement. Behavioral models were made to capture the effects of local dynamics and its collective effects. These models were shown to have a good correlation with the HSPICE circuit simulations and measured values.

Multiple oscillator topologies and architectures were fabricated to test the model, behavior and subsequent analysis. Different pulse amplifier based ring oscillators show trends similar to that predicted by simulations and empirical relationships developed using behavioral simulations. Further transmission line stabilized traveling wave version of the pulse oscillators show a higher stability improvement.

This work opens up a new design space in the timing circuits design where all the other conventional tricks are still applicable. It also opens up an application space due to the timing stability improvement in the order of 1000 cycles where conventional ADC’s and TDC’s work. Finally this work eases up the constraints of loop filter and source phase noise when oscillators are operated in a phase locked loop.