MAX4112 View Datasheet(PDF) - Maxim Integrated
Part Name
Description
Manufacturer
MAX4112 Datasheet PDF : 12 Pages
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Single/Dual/Quad, 400MHz, Low-Power,
Current Feedback Amplifiers
At low gains, G x RIN << RF. Therefore, the closed-loop
bandwidth is essentially independent of closed-loop
gain. Similarly, ZOL >> RF at low frequencies, so that:
( ) VOUT
VIN
= G = 1+
RF / RG
Layout and Power-Supply Bypassing
The MAX4112/MAX4113/MAX4117–MAX4120 have an
RF bandwidth and consequently require careful board
layout, including the possible use of constant-impedance
microstrip or stripline techniques.
To realize the full AC performance of these high-speed
amplifiers, pay careful attention to power-supply
bypassing and board layout. The PCB should have at
least two layers: a signal and power layer on one side,
and a large, low-impedance ground plane on the other
side. The ground plane should be as free of voids as
possible. With multilayer boards, locate the ground
plane on a layer that incorporates no signal or power
traces.
Regardless of whether a constant-impedance board is
used, observe the following guidelines when designing
the board. Wire-wrapped boards are much too induc-
tive, and breadboards are much too capacitive; neither
should be used. IC sockets increase parasitic capaci-
tance and inductance, and should not be used. In gen-
eral, surface-mount components give better high-
frequency performance than through-hole components.
They have shorter leads and lower parasitic reac-
tances. Keep lines as short and as straight as possible.
Do not make 90° turns; round all corners.
Observe high-frequency bypassing techniques to
maintain the amplifier’s accuracy. The bypass capaci-
tors should include a 1000pF ceramic capacitor
between each supply pin and the ground plane, locat-
ed as close to the package as possible. Next, place a
VIN
RG
RF
RT
RS
VOUT = -(RF/RG) x VIN
Figure 2a. Inverting Gain Configuration
RO
VOUT
MAX4112
MAX4113
MAX4117
MAX4118
MAX4119
MAX4120
RG
VIN
RT
VOUT = [1+ (RF/RG)] x VIN
RF
RO
VOUT
MAX4112
MAX4113
MAX4117
MAX4118
MAX4119
MAX4120
Figure 2b. Noninverting Gain Configuration
0.01µF to 0.1µF ceramic capacitor in parallel with each
1000pF capacitor, and as close to them as possible.
Then place a 10µF to 15µF low-ESR tantalum at the
point of entry (to the PCB) of the power-supply pins.
The power-supply trace should lead directly from the
tantalum capacitor to the VCC and VEE pins. To mini-
mize parasitic inductance, keep PC traces short and
use surface-mount components.
Table 1. Recommended Component Values
COMPONENT
RF (Ω)
RG (Ω)
RO (Ω)
RT (Ω)
-3dB Small-Signal Bandwidth (MHz)
0.1dB Gain Flatness (MHz)
Large-Signal Bandwidth (MHz)
MAX4112
600
600
49.9
49.9
400
100
280
AVCL = +2
MAX4117
600
600
49.9
49.9
400
100
280
MAX4119
500
500
49.9
49.9
270
100
145
MAX4113
500
69
49.9
49.9
270
115
240
AVCL = +8
MAX4118
330
47
49.9
49.9
300
115
240
MAX4120
330
47
49.9
49.9
300
115
240
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