AD9259 datasheet(38/53 Pages) AD

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Data Sheet

AD9259

Rev. E | Page 37 of 52

ALTERNATIVE ANALOG INPUT DRIVE

CONFIGURATION

The following is a brief description of the alternative analog input

drive configuration using the AD8332 dual VGA. If this drive

option is in use, some components may need to be populated, in

which case all the necessary components are listed in Table 17. For

more details on the AD8332 dual VGA, including how it works

and its optional pin settings, consult the AD8332 data sheet.

To configure the analog input to drive the VGA instead of the

default transformer option, the following components need to

be removed and/or changed.

•

Remove R102, R115, R128, R141, R161, R162, R163, R164,

T101, T102, T103, and T104 in the default analog input path.

•

Populate R101, R114, R127, and R140 with 0 Ω resistors in

the analog input path.

•

Populate R105, R113, R118, R124, R131, R137, R151, and

R160 with 0 Ω resistors in the analog input path to connect

the AD8332.

•

Populate R152, R153, R154, R155, R156, R157, R158, R159,

C103, C105, C110, C112, C117, C119, C124, and C126

with 10 kΩ resistors to provide an input common-mode

level to the ADC analog inputs.

•

Remove R305, R306, R313, R314, R405, R406, R412, and

R424 to configure the AD8332.

In this configuration, L301 to L308 and L401 to L408 are

populated with 0 Ω resistors to allow signal connection and

use of a filter if additional requirements are necessary.

AD9259 Datasheet(PDF) 38 Page - Analog Devices