EMIF09-02726S3 Просмотр технического описания (PDF) - STMicroelectronics

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EMIF09-02726S3

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CROSSTALK BEHAVIOR

1- Crosstalk phenomena

Fig. A7: Crosstalk phenomena

RG1

VG1

RG2

VG2

line 1

line 2

EMIF09-02726Sx

RL1

α1VG1 + β12VG2

RL2

α 2VG2 + β21VG1

DRIVERS

RECEIVERS

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. A8: Digital crosstalk measurements

+5V

74HC04

EMIF09-02726Sx

+5V

74HC04

Line 1

Square

+5V

Pulse

Generator

5KHz

VG1

Line 2

β 21 VG1

Figure A8 shows the measurement circuit used to quantify the crosstalk effect in a classical digital

application.

Figure A9 shows that in the case of a signal from 0 to 5V with a rise time of a few tenths of ns, the impact

on the disturbed line is less than 100mV peak to peak. No data disturbance is noted on the concerned line.

The same results are obtained with falling edges.

Note: The measurements have been performed in the worst case i.e. on two adjacent cells (1/20 & 2/19).

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