AD8340 datasheet(16/20 Pages) AD

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AD8340

Rev. 0 | Page 16 of 20

EVALUATION BOARD

The evaluation board circuit schematic for the AD8340 is

shown in Figure 39.

The evaluation board is configured to be driven from a

single-ended 50 Ω source. Although the input of the AD8340 is

differential, it may be driven single-ended, with no loss of

performance.

The low-pass corner frequency of the baseband I and Q chan-

nels can be reduced by installing capacitors in the C11 and C12

positions. The low-pass corner frequency for either channel is

approximated by

0.5

kHz

3dB

≈

external

On this evaluation board, the I and Q baseband circuits are

identical to each other, so the following description applies

equally to each. The connections and circuit configuration for

the Q baseband inputs are described in Table 4.

The baseband input of the AD8340 requires a differential volt-

age drive. The evaluation board is set up to allow such a drive by

connecting the differential voltage source to QBBP and QBBM.

The common-mode voltage should be maintained at approxi-

mately 0.5 V. For this configuration, Jumpers W1 to W4 should

be removed.

The baseband input of the evaluation board may also be driven

with a single-ended voltage. In this case, a bias level is provided

to the unused input from Potentiometer R10 by installing either

W1 or W2.

Setting SW1 in Position B disables the AD8340 output amplifier.

With SW1 set to Position A, the output amplifier is enabled.

With SW1 set to Position A, an external voltage signal, such as a

pulse, can be applied to the DSOP SMA connector to exercise

the output amplifier enable/disable function.

AD8340 Datasheet(PDF) 16 Page - Analog Devices