DALC208

Crosstalk behavior

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3

Crosstalk behavior

3.1

Crosstalk phenomena

Figure 13.

Crosstalk phenomena

The crosstalk phenomenon is 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 in Figure 13 the expected signal on load R

α

point has got an extra value

β

crosstalk phenomenon of line 1 on 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 disturbed line will be more affected if it works with low voltage signal or high load

impedance (few k

Ω). The following sections give the value of both digital and analog

crosstalk.

3.2

Digital crosstalk

Figure 14 shows the measurement circuit used to quantify the crosstalk effect in a classical

digital application. Figure 15 shows that in such a condition: signal from 0 V to 5 V 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.

Line 1

Line 2

DRIVERS

RECEIVERS

α

β

+

1

12

α

β

+

2

21

Figure 14.

Digital crosstalk measurements

Figure 15.

Digital crosstalk results

DALC208SC6

100nF

+5V

Line 1

Line 2

+5V

+5V

74HC04

+5V

Square

Pulse

Generator

5KHz

74HC04