  Most PLL architectures have inherent trade-off between settling time and
jitter. This trade-off is ignored by commonly used Figure of Merit (FoM) for
PLL, which considers only jitter and power for benchmarking PLL performance.
This work proposes new Figure of Merit for PLL, which considers settling time
also as performance parameter, along with jitter and power. In this work,
trade-off between settling time and jitter is analyzed in
linear/non-linear/hybrid PLLs, theoretically and with behavioral simulations.
Then, based on settling time vs. jitter relation obtained, currently used
Figure of Merit for PLL is modified to consider all important specifications
i.e. lock time, power and jitter.
