Datasheet

time
Dispersion
Slew Rate Dispersion
0
-
+
Output Differential Signal
Input Differential Signal
0
-
+
time
time
-100 mV
Overdrive 10 mV
Overdrive 100 mV
time
Dispersion
Overdrive Dispersion
0
-
+
Output Differential Signal Input Differential Signal
0
-
+
LMH7220
SNOSAL3E –SEPTEMBER 2006–REVISED MAY 2013 www.ti.com
Amplitude Overdrive Dispersion
One of the parameters that causes dispersion is the amplitude variation of the input signal. Figure 24 shows the
dispersion due to a variation of the input overdrive voltage. The overdrive is defined as the ‘goto’ differential
voltage applied to the inputs. Figure 24 shows the impact it has on the propagation delay time if overdrive is
varied from 10 millivolts to 100 millivolts. This parameter is measured with a constant slew rate of the input
signal.
Figure 24. Overdrive Dispersion
The overdrive dispersion is caused by the fact that switching currents in the input stage depend on the level of
the differential input signal.
Slew Rate Dispersion
The slew rate is another parameter that affects propagation delay. The higher the input slew rate, the faster the
input stage switches (Figure 25).
Figure 25. Slew Rate Dispersion
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