MAX4430 Datasheet, PDF (9/12 Pages) Maxim Integrated Products – Dual-Supply, 180MHz, 16-Bit Accurate, Ultra-Low Distortion Op Amps

Dual-Supply, 180MHz, 16-Bit Accurate,
Ultra-Low Distortion Op Amps
Detailed Description
The MAX4430–MAX4433 are wide-bandwidth, ultra-low-
distortion, voltage-feedback amplifiers. The MAX4430/
MAX4432 are internally compensated for unity gain.
The MAX4431/MAX4433 are internally compensated for
gains of +2V/V or greater.
These amplifiers have ultra-fast 37ns (MAX4430/
MAX4432) 16-bit settling times, 100dB SFDR at 1MHz,
and 4Vp-p output swing with minimum 110dB open-
loop gain.
High-Speed ADC Input Driver Application
The MAX4430–MAX4433 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).
Inverting and Noninverting Configurations
The circuits typically used for the inverting and non-
inverting configurations of the MAX4430–MAX4433 are
shown in Figures 2a and 2b. The minimum uncondition-
ally stable gain values are 1 for the MAX4430/MAX4432
+V_CC
HIGH-SPEED
14/16-BIT ADC
-V_EE
Figure 1. Typical Application Circuit
V_IN
V_OUT
I_F
A = 1 + ^RF = ^VOUT
R_S VIN
R_S
R_F
and 2 for the MAX4431/MAX4433. Use care in selecting
the value for the resistor marked R_S in both circuits.
From dynamic stability considerations (based on the
part’s frequency response and the input capacitance of
the MAX4430–MAX4433), the maximum recommended
value for R_S is 500Ω. In general, lower R_S values will
yield a higher bandwidth and better dynamic stability,
at the cost of higher power consumption, higher power
dissipation in the IC, and reduced output drive avail-
ability. For a minimum R_S value, take into consideration
that the current indicated as I_F is supplied by the output
stage and must be discounted from the maximum out-
put current to calculate the maximum current available
to the load. I_F can be found using the following equa-
tion:
I_F = V_IN(MAX) / R_S
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.
Applications Information
Layout and Power-Supply Bypassing
The MAX4430–MAX4433 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
R_S
V_IN
R_B
R_F
I_F
V_OUT
A = ^{- RF} = ^VOUT
R_S
V_IN
Figure 2a. Noninverting Configuration
Figure 2b. Inverting Configuration
_______________________________________________________________________________________ 9