DALC208(1999) Просмотр технического описания (PDF) - STMicroelectronics
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DALC208 Datasheet PDF : 10 Pages
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DALC208SC6
CROSSTALK BEHAVIOR
1- Crosstalk phenomena
Fig. A4: Crosstalk phenomena.
RG1
VG1
RG2
VG2
Line 1
Line 2
RL1
α1VG1 + β12VG2
RL2
α 2VG2 + β21VG1
DRIVERS
The crosstalk phenomena are due to the coupling
between 2 lines. The coupling factor (β12 or β21)
increases when the gap across lines decreases,
particularly in silicon dice. In the example above
the expected signal on load RL2 is α2VG2, in fact
the real voltage at this point has got an extra value
β21VG1. This part of the VG1 signal represents the
effect of the crosstalk phenomenon of the line 1 on
the line 2. This phenomenon has to be taken into
account when the drivers impose fast digital data
or high frequency analog signals in the disturbing
line. The perturbed line will be more affected if it
works with low voltage signal or high load
impedance (few kΩ). The following chapters give
the value of both digital and analog crosstalk.
2- Digital Crosstalk
Fig. A5: Digital crosstalk measurements.
RECEIVERS
Fig. A6: Digital crosstalk results.
+5V
+5V
+5V
74HC04
100nF
74HC04
Line 1
Square
+5V
Pulse
Generator
5KHz
VG1
Line 2
β21 VG1
DALC208SC6
Figure A5 shows the measurement circuit used to
quantify the crosstalk effect in a classical digital
application.
Figure A6 shows that in such a condition: signal
from 0V to 5V and a rise time of 5 ns, the impact on
the disturbed line is less than 100mV peak to peak.
No data disturbance was noted on the concerned
line. The same results were obtained with falling
edges.
Note: The measurements have been done in the worst case i.e. on
two adjacent cells (I/O1 & I/O4).
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