
REV. D
AD8002
–14–
Table I. Recommended Component Values
AD8002AN (DIP)
AD8002AR (SOIC)
Gain
Component
–10
–2
–1
+1
+2
+10
+100
–10
–2
–1
+1
+2
+10
+100
RF (
)
499
549
576
1210
750
499
1000
499
549
953
681
499
1000
RG (
)
49.9
274
576
–
750
54.9
10
49.9
249
549
–
681
54.9
10
RBT (Nominal) (
)
49.9
RC (
)*
75
0
75
0
RS (
)
49.9
RT (Nominal) (
)
–
61.9
54.9
49.9
–
61.9
54.9
49.9
Small Signal BW (MHz)
270
380
410
600
500
170
17
250
410
600
500
170
17
0.1 dB Flatness (MHz)
45
80
130
35
60
24
3
50
100
35
90
24
3
AD8002ARM ( SOIC)
Gain
Component
–10
–2
–1
+1
+2
+10
+100
RF (
)
499
590
1000
681
499
1000
RG (
)
49.9
249
590
–
681
54.9
10
RBT (Nominal) (
)
49.9
RC (
)*
75
0
RS (
)
49.9
RT (Nominal) (
)
–
61.9
49.9
Small Signal BW (MHz)
270
400
410
600
450
170
19
0.1 dB Flatness (MHz)
60
100
35
70
35
3
*RC is recommended to reduce peaking, and minimizes input reflections at frequencies above 300 MHz. However, R C is not required.
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 selec-
tion are mandatory.
The PCB should have a ground plane covering all unused por-
tions of the component side of the board to provide a low
impedance ground path. The ground plane should be removed
from the area near the input pins to reduce stray capacitance.
Chip capacitors should be used for supply bypassing (see Figure
13). One end should be connected to the ground plane and the
other within 1/8 in. of each power pin. An additional large tanta-
lum electrolytic capacitor (4.7
F–10 F) should be connected in
parallel, but not necessarily so close, to supply current for fast,
large-signal changes at the output.
The feedback resistor should be located close to the inverting
input pin in order to keep the stray capacitance at this node to a
minimum. Capacitance variations of less than 1 pF at the invert-
ing input will significantly affect high-speed performance.
Stripline design techniques should be used for long signal traces
(greater than about 1 in.). These should be designed with a
characteristic impedance of 50
or 75 and be properly termi-
nated at each end.
Inverting Configuration
Supply Bypassing
Noninverting Configuration
RF
RBT
IN
+VS
–VS
RS
RT
RG
OUT
C1
0.1 F
C3
10 F
C2
0.1 F
C4
10 F
+VS
–VS
RF
RBT
IN
+VS
–VS
RT
RG
OUT
*RC
*SEE TABLE I
Figure 13. Inverting and Noninverting Configurations