MAX4309ESA MAXIM [Maxim Integrated Products], MAX4309ESA Datasheet - Page 11

• Manufacturer Part Number: MAX4309ESA
• Description: 400MHz, Ultra-Low-Distortion Op Amps
• Manufacturer: MAXIM [Maxim Integrated Products]

before the reactive load prevents ringing and oscilla-
tion. At higher capacitive loads, AC performance will be
controlled by the interaction of the load capacitance
and isolation resistor. Figures 3a–3c show the effect of
an isolation resistor on the MAX4108/MAX4109/
MAX4308/MAX4309 closed-loop response.
Coaxial cable and other transmission lines are easily
driven when terminated at both ends with their charac-
teristic impedance. When driving back-terminated
transmission lines, the capacitance of the transmission
line is essentially eliminated.
Input buffer amplifiers can be a source of significant
errors in high-speed ADC applications. The input buffer
is usually required to rapidly charge and discharge the
ADC’s input, which is often capacitive (see the section
Driving Capacitive Loads ). In addition, a high-speed
ADC’s input impedance often changes very rapidly
during the conversion cycle, requiring an amplifier with
very low output impedance at high frequencies to main-
tain measurement accuracy. The combination of high
speed, fast slew rate, low noise, and a low and stable
distortion over load makes the MAX4108/MAX4109/
MAX4308/MAX4309 ideally suited for use as buffer
amplifiers in high-speed ADC applications.
Figure 3a. MAX4108 Response vs. Capacitive Load with
Resistive (R
S
12
10
-2
-4
-6
-8
) Isolation (circuit shown in Figure 1a)
2
8
6
4
0
0.1
C
A
L
VCL
= 10pF
______________________________________________________________________________________
= +1
400MHz, Ultra-Low-Distortion Op Amps
1
FREQUENCY (MHz)
10
R
S
ADC Input Buffers
= 10
R
R
S
S
= 30
= 22
100
1000
Figure 3b. MAX4308 Response vs. Capacitive Load with
Resistive (R
Figure 3c. MAX4108/MAX4309 Response vs. Capacitive Load
with Resistive (R
S
) Isolation (circuit shown in Figure 1a)
-1
-2
-3
-4
-5
-6
11
10
4
3
2
1
0
1
9
8
7
6
5
4
3
2
0.1
0.1
S
) Isolation (circuit shown in Figure 1a)
C
A
C
A
VCL
V
L
L
R
R
R
= 10pF
= 10pF
= +5
S
S
S
= 8.2
= 15
= 47
= +2
1
1
FREQUENCY (MHz)
FREQUENCY (MHz)
10
10
R
S
= 15
100
100
R
S
= 8.2
1000
1000
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