Steady-state analysis of voltage and current controlled oscillators
ICCAD '05 Proceedings of the 2005 IEEE/ACM International conference on Computer-aided design
Robust Harmonic-Probe method for the simulation of oscillators
IEEE Transactions on Circuits and Systems Part I: Regular Papers - Special section on 2009 IEEE custom integrated circuits conference
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The oscillator problem consists of determining good initialvalues for the node voltages and the frequency of oscillationand the avoidance of the DC solution. Standard approachesfor limit cycle calculations of autonomous circuitsexhibit poor convergence behavior in practice. By introducingan additional periodic probe voltage source to the oscillatorcircuit, the system of autonomous differential alge-braicequations (DAEs) can be reformulated as a system ofnon-autonomous DAEs with the constraint, that the currentthrough the source has to be zero for the limit cycle. Using atwo stage approach leads to a greater range of convergenceas the standard approach, but the success of the algorithmis heavily dependent on the initial amplitude of the probesource and the frequency of oscillation. This paper presentsa fast and reliable optimization based initialization procedurewhich overcomes the initialization problem of the twostage algorithm.