1–18 Altera Corporation
Stratix Device Handbook, Volume 2 July 2005
Enhanced PLLs
Figure 1–7. extclkena Signals
Programmable Bandwidth
Enhanced PLLs provide advanced control of the PLL bandwidth using
the programmable characteristics of the PLL loop, including loop filter
and charge pump.
Background
The PLL bandwidth is the measure of the PLLs ability to track the input
clock and jitter. It is determined by the −3-dB frequency of the closed-loop
gain in the PLL or approximately the unity gain point for open loop PLL
response. As Figure 1–8 shows, these points correspond to approximately
the same frequency.
COUNTER
OUTPUT
CLKENA
CLKOUT
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