AD8002

Data Sheet

Rev. E | Page 18 of 21

APPLICATIONS INFORMATION

LAYOUT CONSIDERATIONS

The specified high speed performance of the AD8002 requires

careful attention to board layout and component selection.

Proper RF design techniques and low parasitic component

selection are mandatory.

Use a ground plane to cover all unused portions of the

component side of the board to provide a low impedance

ground path. Remove the ground plane from the area near

the input pins to reduce stray capacitance.

Use chip capacitors for supply bypassing (see Figure 58). Connect

one end to the ground plane and the other within ⅛ inch of

each power pin. Connect an additional large tantalum

electrolytic capacitor (4.7 µF to 10 µF) in parallel, but not

necessarily so close, to supply current for fast, large signal

changes at the output.

Locate the feedback resistor close to the inverting input pin

to keep the stray capacitance at this node to a minimum.

Capacitance variations of less than 1 pF at the inverting input

significantly affects high speed performance.

Use stripline design techniques for long signal traces (greater than

about 1 inch). Design these with a characteristic impedance of

50 Ω or 75 Ω and ensure they are properly terminated at each

end.

Table 4 and Table 5 show the recommended component values.

RF

RBT

IN

–VS

+VS

RS

RT

RG

OUT

Figure 57. Inverting Configuration

C1

0.1µF

C3

10µF

C2

0.1µF

C4

10µF

+VS

–VS

Figure 58. Supply Bypassing

RF

RBT

IN

–VS

+VS

RT

RG

OUT

RC

Figure 59. Noninverting Configuration

Table 4. AD8002AR (SOIC) Recommended Component Values1

Component

Gain

Unit

−10

−2

−1

+1

+2

+10

+100

RF

499

499

549

953

681

499

1000

Ω

RG

49.9

249

549

N/A

681

54.9

10

Ω

RBT (Nominal)

49.9

49.9

49.9

49.9

49.9

49.9

49.9

Ω

RC2

N/A

N/A

N/A

75

75

0

0

Ω

RS

49.9

49.9

49.9

N/A

N/A

N/A

N/A

Ω

RT (Nominal)

N/A

61.9

54.9

49.9

49.9

49.9

49.9

Ω

Small Signal Bandwidth

250

410

410

600

500

170

17

MHz

0.1 dB Flatness

50

100

100

35

90

24

3

MHz

1

N/A means not applicable

2

RC is recommended to reduce peaking, and minimizes input reflections at frequencies above 300 MHz. However, RC is not required.

Table 5. AD8002ARM (MSOP) Recommended Component Values1

Component

Gain

Unit

−10

−2

−1

+1

+2

+10

+100

RF

499

499

590

1000

681

499

1000

Ω

RG

49.9

249

590

N/A

681

54.9

10

Ω

RBT (Nominal)

49.9

49.9

49.9

49.9

49.9

49.9

49.9

Ω

RC2

N/A

N/A

N/A

75

75

0

0

Ω

RS

49.9

49.9

49.9

N/A

N/A

N/A

N/A

Ω

RT (Nominal)

N/A

61.9

49.9

49.9

49.9

49.9

49.9

Ω

Small Signal Bandwidth

270

400

410

600

450

170

19

MHz

0.1 dB Flatness

60

100

100

35

70

35

3

MHz

1

N/A means not applicable

2

RC is recommended to reduce peaking, and minimizes input reflections at frequencies above 300 MHz. However, RC is not required.