AD9775 datasheet(44/56 Pages) AD

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AD9775

Rev. E | Page 44 of 56

EVALUATION BOARD

The AD9775 evaluation board allows easy configuration of the

various modes, programmable via the SPI port. Software is

available for programming the SPI port from PCs running

Windows® 95, Windows 98, or Windows NT®/2000. The

evaluation board also contains an AD8345 quadrature

modulator and support circuitry that allows the user to

optimally configure the AD9775 in an image reject transmit

signal chain.

Figure 101 to Figure 104 show how to configure the evaluation

board in the one-port and two-port input modes with the PLL

enabled and disabled. Refer to Figure 105 to Figure 114, the

schematics, and the layout for the AD9775 evaluation board for

the jumper locations described in the DAC Single-Ended

Outputs section. The AD9775 outputs can be configured for

various applications by referring to the following instructions.

DAC Single-Ended Outputs

Remove Transformers T2 and T3. Solder jumper links JP4 or JP28

to look at the DAC1 outputs. Solder jumper links JP29 or JP30 to

look at the DAC2 outputs. Jumper 8 and Jumper 13 to Jumper 17

should remain unsoldered. Jumper JP35 to Jumper JP38 can be

used to ground one of the DAC outputs while the other is

measured single ended. Optimum single-ended distortion

performance is typically achieved in this manner. The outputs

are taken from S3 and S4.

DAC Differential Outputs

Transformers T2 and T3 should be in place. Note that the lower

band of operation for these transformers is 300 kHz to 500 kHz.

Jumper 4, Jumper 8, Jumper 13 to Jumper 17, and Jumper 28 to

Jumper 30 should remain unsoldered. The outputs are taken

from S3 and S4.

Using the AD8345

Remove Transformers T2 and T3. Jumper JP4 and Jumper 28 to

Jumper 30 should remain unsoldered. Jumper 13 to Jumper 16

should be soldered. The desired components for the low-pass

interface filter L6, L7, C55, and C81 should be in place. The LO

drive is connected to the AD8345 via J10 and the balun T4, and

the AD8345 output is taken from J9.

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