AD8022

–13–

REV. 0

AD8022

AD8022

U27

U27

12V

1k

1%

1k

1%

1

8

3

2

7

4

6

5

1.69k

1%

0.1 F

50V

5%

NPO

820pF

10%

820pF

10%

680pF

5% NPO

2.43k

1%

1.91k

1%

6V

0.1 F

16V

10%

X7R

2.43k

1%

1.91k

1%

680pF

5% NPO

Figure 38. Differential Input Sallen-Key Filter Using

AD8022 on Single Supply, 12 V

EVALUATION BOARDS

The evaluation board layout of Figures 40, 41, and 42 is our

standard dual SOIC noninverting evaluation circuit offering

the ability to evaluate the AD8022 in typical op amp circuits,

is available from Analog Devices Inc. In addition, the AD8022

receiver function may be added to on our ADSL EVAL boards.

The AD8016ARB-EVAL, the AD8016ARP-EVAL, the

AD8017AR-EVAL and AD8018ARU-EVAL boards are avail-

able through Analog Devices. These platforms provide the

capability to fully evaluate the Analog Devices ADSL trans-

ceiver hybrid. All of the ADSL evaluation boards mentioned

above can accommodate the evaluation of the AD8022 as a

receiver amplifier when installed in the U2 location. The receiver

circuit on these boards is typically unpopulated. Requesting

samples of the AD8022 along with the EVAL board of your

choice will provide the capability to evaluate the AD8022 along

with many other Analog Devices ADSL line driver products in a

typical transceiver circuit. The evaluation circuits have been

designed to replicate the CPE or CO side analog transceiver

hybrid circuits.

The ADSL EVAL circuits mentioned above are designed using a

two transformer transceiver topology, including a line receiver, line

driver, line matching network, an RJ11 jack for interfacing to

line simulators, and transformer-coupled inputs for single-to-

differential input conversion.

Layout Considerations

As is the case with all “hi speed” amplifiers, careful attention to

printed circuit board layout details will prevent associated board

parasitics from becoming problematic. Proper RF design technique

is mandatory. The PCB should have a ground plane covering all

unused portions of the component side of the board to provide a

low-impedance return path. Removing the ground plane from

the area near the input signal lines will reduce stray capacitance.

Chip capacitors should be used for the supply bypassing. One

end of the capacitor connected to the ground plane and the other

no more than 1/8 inch away from each supply pin. An additional

large (0.47

µF to 10 µF) tantalum capacitor should be connected

in parallel, although not necessarily as close, in order to supply

current for fast, large signal changes at the AD8022 output.

Signal lines connecting the feedback and gain resistors should

be as short as possible, minimizing the inductance and stray

capacitance associated with these traces. Locate termination

resistors and loads as close as possible to the input(s) and out-

put respectively. Adhere to stripline design techniques for long

signal traces (greater than about 1 inch). Following these

generic guidelines will improve the performance of the AD8022

in all applications.

FREQUENCY – Hz

10k

–47.5

100k

1M

10M

–42.5

–37.5

–32.5

–27.5

–22.5

–17.5

–12.5

–7.5

–2.5

2.5

7.5

Figure 39. Frequency Response of Sallen-Key Filter