0.0

0.1

0.2

0.3

0.4

0.5

-3

-2

-1

0

1

2

0

1

2

3

4

5

TIME ( s)

High Power Mode

Low Power Mode

Enable

VOUT

SVA-30206567

L2

L1

C1

C2

L5

ADC VIN +

ADC VIN -

ADC VCM

AMP VOUT -

AMP VOUT +

R1

R2

SVA-30206513

LMH6523

www.ti.com

SNOSC88 – DECEMBER 2012

Figure 56. Sample Filter

POWER SUPPLIES

The LMH6523 was designed primarily to be operated on 5V power supplies. The voltage range for V+ is 4.75V to

5.25V. Power supply accuracy of 2.5% or better is advised. When operated on a board with high speed digital

signals it is important to provide isolation between digital signal noise and the LMH6523 inputs. The

SP16160CH1RB reference board provides an example of good board layout.

DYNAMIC POWER MANAGEMENT, USING LOW POWER MODE

The LMH6523 offers the option of a reduced power mode of operation referred to as Low Power Mode. In this

mode of operation power consumption is reduced by approximately 20%. In many applications the linearity of the

LMH6523 is fully adequate for most signal conditions. This would apply for a radio in a noise limited environment

with no close-in blocker signals. During these conditions the LMH6523 can be operated in the low power mode.

When a blocking signal is detected, or when system dynamic range needs to be increased, the LMH6523 can be

rapidly switched from the Low Power Mode to the standard, High Power Mode.

The output response shown in Figure 57 is for a 2 MHz switching frequency pulse applied to the enable pin with

a 50 MHz input signal. Analysis with a spectrum analyzer showed that the power mode switching spurs created

by the switching signal were

−80dBc with respect to the 50 MHz tone signal. This shows that rapid switching of

power modes has virtually no impact on the signal quality.

Figure 57. Signal Output During Mode Change from High Power Mode to Low Power Mode

Copyright © 2012, Texas Instruments Incorporated

Submit Documentation Feedback

25

Product Folder Links: LMH6523