LMH6574 datasheet(12/15 Pages) NSC

12 / 15 page

Application Notes (Continued)

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 (R

1 and C1 decay)

but won’t delay its L to H transition. R

2 should be kept small

compared to R

1 in order to not reduce the SHUTDOWN

voltage and to produce little or no delay to SHUTDOWN.

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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FIGURE 4. 8:1 MUX USING TWO LMH6574’s

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FIGURE 5. Delay Circuit Implementation

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