MAX4434 Maxim, MAX4434 Datasheet - Page 9

• Manufacturer Part Number: MAX4434
• Description: The MAX4434/MAX4435 single and MAX4436/MAX4437 dual operational amplifiers feature wide bandwidth, 16-bit settling time in 23ns, and low-noise/low-distortion operation
• Manufacturer: Maxim

The MAX4434–MAX4437 are wide-bandwidth, ultra-low-
distortion, voltage-feedback amplifiers. The MAX4434/
MAX4436 are internally compensated for unity gain.
The MAX4435/MAX4437 are internally compensated for
gains of +5V/V or greater.
These amplifiers have ultra-fast 35ns (MAX4434/
MAX4436) 16-bit settling times, -97dB SFDR at 1MHz,
and 4Vp-p output swing with minimum 115dB open-
loop gain.
The MAX4434–MAX4437 op amps are ideal for driving
high-speed 14- to 16-bit ADCs. In most cases, these
ADCs operate with a charge balance scheme, with
capacitive loads internally switched on and off from the
input. The driver used must withstand these changing
capacitive loads while holding the signal amplitude sta-
bility consistent with the ADC’s resolution and, at the
same time, have a frequency response compatible with
the sampling speed of the ADC (Figure 1).
The circuits typically used for the inverting and non-
inverting configurations of the MAX4434–MAX4437 are
shown in Figures 2a and 2b. The minimum uncondition-
ally stable gain values are 1 for the MAX4434/MAX4436
Figure 1. Typical Application Circuit
Figure 2a. Noninverting Configuration
Inverting and Noninverting Configurations
High-Speed ADC Input Driver Application
R
V
IN
S
_______________________________________________________________________________________
V
V
Single-Supply, 150MHz, 16-Bit Accurate,
CC
EE
R
F
Detailed Description
I
F
14/16-BIT ADC
HIGH-SPEED
A = 1 +
V
OUT
R
R
S
F
Ultra-Low Distortion Op Amps
=
V
V
OUT
IN
and 5 for the MAX4435/MAX4437. Use care in selecting
the value for the resistor marked R
dynamic stability considerations (based on the part’s fre-
quency response and the input capacitance of the
MAX4434–MAX4437), the maximum recommended
value for R
yield a higher bandwidth and better dynamic stability, at
the cost of higher power consumption, higher power dis-
sipation in the IC, and reduced output drive availability.
For a minimum R
current indicated as I
and must be discounted from the maximum output cur-
rent to calculate the maximum current available to the
load. I
If DC thermal stability is an important design concern,
the Thevenin resistance seen by both inputs at DC
must be balanced. This includes the resistance of the
signal source and termination resistors if the amplifier
signal input is fed from a transmission line. The capaci-
tance associated with the feedback resistors must also
be considered as a possible limitation to the available
bandwidth or to the dynamic stability. Only resistors
with small parallel capacitance specifications should
be considered.
The MAX4434–MAX4437 have wide bandwidth and
consequently require careful board layout. 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 a large low-
impedance ground plane that is as free of voids as
possible. Do not use commercial breadboards. Keep
signal lines as short and straight as possible. Observe
high-frequency bypassing techniques to maintain the
amplifier’s accuracy and stability. In general, use sur-
Figure 2b. Inverting Configuration
V
F
IN
can be found using the following equation:
Layout and Power-Supply Bypassing
S
is 500Ω. In general, lower R
R
R
S
Applications Information
B
S
value, take into consideration that the
I
F
= V
F
is supplied by the output stage
IN(MAX)
R
F
/ R
S
in both circuits. From
I
S
F
V
A =
OUT
S
- R
values will
R
S
F
=
V
OUT
V
IN
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