AD8002ARZ Datasheet, PDF (14/20 Pages) Analog Devices – Dual 600 MHz, 50 mW Current Feedback Amplifier

AD8002
Layout Considerations
The specified high-speed performance of the AD8002 requires
careful attention to board layout and component selection.
Proper R_F 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 µF–10 µF) 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 Ω or 75 Ω and be properly termi-
nated at each end.
R_F
+V_S
R_G
IN
R_T
R_S
–V_S
R_BT
OUT
Inverting Configuration
+V_S
C1
0.1␮F
C3
10␮F
C2
0.1␮F
C4
10␮F
–V_S
Supply Bypassing
R_F
+V_S
R_G
IN
*R_C
R_BT
OUT
R_T
–V_S
*SEE TABLE I
Noninverting Configuration
Figure 13. Inverting and Noninverting Configurations
Table I. Recommended Component Values
AD8002AN (DIP)
Gain
AD8002AR (SOIC)
Gain
Component
–10 –2 –1 +1 +2 +10 +100 –10 –2 –1 +1 +2 +10 +100
R_F (Ω)
499 549 576 1210 750 499 1000 499 499 549 953 681 499 1000
R_G (Ω)
49.9 274 576 –
750 54.9 10 49.9 249 549 –
681 54.9 10
R_BT (Nominal) (Ω)
49.9 49.9 49.9 49.9 49.9 49.9 49.9 49.9 49.9 49.9 49.9 49.9 49.9 49.9
R_C (Ω)*
75 75 0
0
75 75 0
0
R_S (Ω)
49.9 49.9 49.9
49.9 49.9 49.9
R_T (Nominal) (Ω)
–
61.9 54.9 49.9 49.9 49.9 49.9 –
61.9 54.9 49.9 49.9 49.9 49.9
Small Signal BW (MHz) 270 380 410 600 500 170 17 250 410 410 600 500 170 17
0.1 dB Flatness (MHz) 45 80 130 35 60 24 3
50 100 100 35 90 24 3
AD8002ARM (␮SOIC)
Gain
Component
–10 –2 –1 +1 +2 +10 +100
R_F (Ω)
499 499 590 1000 681 499 1000
R_G (Ω)
49.9 249 590 –
681 54.9 10
R_BT (Nominal) (Ω)
49.9 49.9 49.9 49.9 49.9 49.9 49.9
R_C (Ω)*
75 75 0
0
R_S (Ω)
49.9 49.9 49.9
R_T (Nominal) (Ω)
–
61.9 49.9 49.9 49.9 49.9 49.9
Small Signal BW (MHz) 270 400 410 600 450 170 19
0.1 dB Flatness (MHz) 60 100 100 35 70 35 3
*R_C is recommended to reduce peaking, and minimizes input reflections at frequencies above 300 MHz. However, R _C is not required.
–14–
REV. D