MAX4224ESA Maxim Integrated Products, MAX4224ESA Datasheet - Page 11

• Manufacturer Part Number: MAX4224ESA
• Description: High Speed Op Amplifiers Integrated Circuits (ICs)
• Manufacturer: Maxim Integrated Products

Specifications of MAX4224ESA

• Lead Free Status / Rohs Status: No

To realize the full AC performance of these high-speed
amplifiers, pay careful attention to power-supply
bypassing and board layout. The PC board should
have at least two layers: a signal and power layer on
one side and a large, low-impedance ground plane on
the other. The ground plane should be as free of voids
as possible, with one exception: the inverting input pin
(IN-) should have as low a capacitance to ground as
possible. This means that there should be no ground
plane under IN- or under the components (R
connected to it. With multilayer boards, locate the
ground plane on a layer that incorporates no signal or
power traces.
Whether or not a constant-impedance board is used, it
is best to observe the following guidelines when
designing the board:
1) Do not use wire-wrapped boards (they are too
2) Do not use IC sockets. IC sockets increase reac-
3) Keep signal lines as short and straight as possible.
4) Observe high-frequency bypassing techniques to
5) In general, surface-mount components have shorter
The bypass capacitors should include a 10nF ceramic,
surface-mount capacitor between each supply pin and
the ground plane, located as close to the package as
possible. Optionally, place a 10µF tantalum capacitor
at the power-supply pins’ point of entry to the PC board
to ensure the integrity of incoming supplies. The power-
supply trace should lead directly from the tantalum
capacitor to the V
sitic inductance, keep PC traces short and use surface-
mount components. The N.C. pins should be
connected to a common ground plane on the PC board
to minimize parasitic coupling.
If input termination resistors and output back-termina-
tion resistors are used, they should be surface-mount
types, and should be placed as close to the IC pins as
possible. Tie all N.C. pins to the ground plane to mini-
mize parasitic coupling.
inductive) or breadboards (they are too capacitive).
tance.
Do not make 90° turns; round all corners.
maintain the amplifier’s accuracy and stability.
bodies and lower parasitic reactance, giving better
high-frequency performance than through-hole com-
ponents.
Current-Feedback Amplifiers with Shutdown
CC
______________________________________________________________________________________
and V
EE
pins. To minimize para-
F
and R
G
1GHz, Low-Power, SOT23,
)
As with all current-feedback amplifiers, the frequency
response of these devices depends critically on the
value of the feedback resistor R
internal compensation capacitor to form the dominant
pole in the feedback loop. Reducing R
increases the pole frequency and the -3dB bandwidth,
but also increases peaking due to interaction with other
nondominant poles. Increasing R
peaking and bandwidth.
Table 1 shows optimal values for the feedback resistor
(R
MAX4228. Note that the MAX4224/MAX4227/MAX4228
offer superior AC performance for all gains except unity
gain (0dB). These values provide optimal AC response
using surface-mount resistors and good layout tech-
niques. Maxim’s high-speed amplifier evaluation kits
provide practical examples of such layout techniques.
Stray capacitance at IN- causes feedback resistor
decoupling and produces peaking in the frequency-
response curve. Keep the capacitance at IN- as low as
possible by using surface-mount resistors and by
avoiding the use of a ground plane beneath or beside
these resistors and the IN- pin. Some capacitance is
unavoidable; if necessary, its effects can be counter-
acted by adjusting R
consistency over a wide range of production lots.
Table 1. Optimal Feedback Resistor
Networks
* For the MAX4223EUT, this optimal value is 470 Ω .
F
GAIN
MAX4223/MAX4225/MAX4226
MAX4224/MAX4227/MAX4228
(V/V)
) and gain-setting resistor (R
10
1
2
5
2
5
Choosing Feedback and Gain Resistors
GAIN
(dB)
14
14
20
0
6
6
560*
200
100
470
240
130
(Ω)
R
F
. Use 1% resistors to maintain
F
Open
200
470
R
(Ω)
25
62
15
F
G
. R
G
) for the MAX4223–
F
F
’s value reduces
combines with an
(MHz)
-3dB
1000
BW
380
235
600
400
195
F
’s value
0.1dB
(MHz)
BW
300
115
200
65
90
35
11