LMH6574 Datasheet, PDF (12/15 Pages) National Semiconductor (TI) – 4:1 High Speed Video Multiplexer

Application Notes (Continued)
FIGURE 4. 8:1 MUX USING TWO LMH6574’s
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but won’t delay its L to H transition. R₂ should be kept small
compared to R₁ in order to not reduce the SHUTDOWN
voltage and to produce little or no delay to SHUTDOWN.
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FIGURE 5. Delay Circuit Implementation
If it is important in the end application to make sure that no
two inputs are presented to the output at the same time, an
optional delay block can be added, to drive the SHUTDOWN
pin of each device, as shown. Figure 5 shows one possible
approach to this delay circuit. The delay circuit shown will
delay SHUTDOWN’s H to L transitions (R₁ and C₁ decay)
Other Applications
The LMH6574 could support a multi antenna receiver with
up to four separate antennas. Monitoring the signal strength
of all 4 antennas and connecting the strongest signal to the
final IF stage would provide effective spacial diversity.
For direction finding, the LMH6574 could be used to provide
high speed sampling of four separate antennas to a single
DSP which would use the information to calculate the direc-
tion of the received signal.
DRIVING CAPACITIVE LOADS
Capacitive output loading applications will benefit from the
use of a series output resistor R_OUT. Figure 6 shows the use
of a series output resistor, R_OUT, to stabilize the amplifier
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