500 W

Buffer

VCM

AVDD5

Buffer

1.6pF

GND

~0.5pF

package

~2.5nHBondWire

~200fF

bondpad

GND

package

bondpad

GND

AVDD5

ADS5474/5463/5444/5440

AIN

AIN

~2.5nHBondWire

500 W

~0.5pF

~200fF

1.6pF

R

50

0

W

Z

50

0

W

ADS5463

AIN

AIN

S0176-03

R

200 W

ACSignal

Source

Mini-Circuits

JTX-4-10T

ADS5463

Figure 30. Analog Input Equivalent Circuit

For a full-scale differential input, each of the differential lines of the input signal (pins 16 and 17) swing

symmetrically between 2.4 V + 0.55 V and 2.4 V – 0.55 V. This means that each input has a maximum signal

the characteristics of performance versus input amplitude demonstrated in Figure 18 and Figure 19. For

The maximum swing is determined by the internal reference voltage generator, eliminating the need for any

external circuitry for this purpose.

The ADS5463 obtains optimum performance when the analog inputs are driven differentially. The circuit in

Figure 31 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, which also demonstrates good performance. If voltage gain is required, a step-up transformer can

be used.

Figure 31. 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 the

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

Copyright © 2006–2008, Texas Instruments Incorporated

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