R

50

0

W

Z

50

0

W

ADS5474

AIN

AIN

R

200 W

ACSignal

Source

Mini-Circuits

JTX-4-10T

ADS5474

THS9001

AIN

AIN

VIN

VIN

THS9001

1000pF

1000pF

39pF

50 W

50 W

0.1 F

m

1000pF

1000pF

18 H

m

ADS5474

The ADS5474 performs optimally when the analog inputs are driven differentially. The circuit in Figure 32 shows

one possible configuration using an RF transformer with termination either on the primary or on the secondary of

the transformer. In addition, the evaluation module is configured with two back-to-back transformers, also

demonstrating good performance. If voltage gain is required, a step-up transformer can be used.

Figure 32. Converting a Single-Ended Input to a Differential Signal Using an RF Transformer

In addition to the transformer configurations, Texas Instruments offers a wide selection of single-ended

operational amplifiers that can be selected depending on the application. An RF gain-block amplifier, such as

Texas Instruments' THS9001, can also be used for high-input-frequency applications. For large voltage gains at

intermediate-frequencies in the 50 MHz to 400 MHz range, the configuration shown in Figure 33 can be used.

The component values can be tuned for different intermediate frequencies. The example shown in Figure 33 is

located on the evaluation module and is tuned for an IF of 170 MHz. More information regarding this

configuration can be found in the ADS5474 EVM User Guide (SLAU194) and the THS9001 50-MHz to 350-MHz

Cascadeable Amplifier data sheet (SLOS426), both available for download at www.ti.com.

Figure 33. Using the THS9001 IF Amplifier With the ADS5474

Copyright © 2007–2008, Texas Instruments Incorporated

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Product Folder Link(s): ADS5474