AND8090 Datasheet, PDF (6/20 Pages) ON Semiconductor – AC Characteristics of ECL Devices

AND8090/D
Output Swing − The output swing (V_OUTpp) is measured
between the HIGH and LOW levels of each individual
differential or single−ended output. The output voltage
swing for each individual output is defined by the following
equation and Figure 8.
VOUTPP + VOH * VOL
V_OH
V_OUTpp
50%
50% duty cycle input. A 50% duty cycle input/output is
shown in Figure 9. Note that the HIGH and LOW pulse
widths (PW_H and PW_L respectively) are equal for a 50%
duty cycle signal.
HIGH
50%
LOW
PW_H
PW_L
V_OL
Figure 8. Output Voltage Swing
The V_OUTpp value is shown as the vertical axis in the data
sheet maximum frequency plots (refer to the “Maximum
Input Frequency” section).
SIGNAL TIMING
Duty Cycle − The duty cycle is the ratio of the HIGH pulse
width (PW) to the signal period and is described by the
following equations:
Signal Period = Time between adjacent rising edges
Duty Cycle = (HIGH Pulse Width/Signal Period) * 100%
The 50% points are used to measure the HIGH pulse
width and the signal period. AC characteristics for
ON Semiconductor devices are typically measured for a
Fifty Percent Duty Cycle: PW_{H =} PW_L
Figure 9. Input/Output Duty Cycle
Maximum Input Frequency − This is a typical device
performance value. It is the highest allowable input
frequency for proper device operation (f_MAX). For shift
registers, it is referred to as the Maximum Shift Frequency
(f_SHIFT). It is the frequency where the output voltage swing
(V_OUTpp) is equal to a minimum value that is determined by
the device type, or it is the frequency where the device no
longer functions properly.
An output voltage swing versus input frequency plot is
typically included with data sheets. For the MC100EP90
example shown in Figure 10, the maximum listed input
frequency of 3.0 GHz occurs at an output voltage swing of
approximately 400 mV. The jitter shown in Figure 10 is
described in a later section.
900
9
800
8
700
7
600
6
500
5
400
4
300
3
200
10_{ÉÉ00 ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ(JITTER)}
2
1
0
1000
2000
3000
4000
FREQUENCY (MHz)
Figure 10. Output Voltage vs. Input Frequency Example
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