AD8340

Data Sheet

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

channels can be reduced by installing capacitors in the C11 and

C12 positions. The low-pass corner frequency for either

channel is approximated by

pF

5

.

0

nF

10

kHz

45

dB

3

+

×

≈

EXTERNAL

C

f

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

identical, 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

voltage 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

approximately 0.5 V. For this configuration, Jumper W1 to

Jumper W4 should be removed.

The baseband input of the evaluation board can 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 and an external voltage signal, such as a pulse, can be

applied to the DSOP SMA connector to exercise the output

amplifier enable/disable function.

Rev. C | Page 16 of 20