MAX4435ESA datasheet(9/12 Pages) MAXIM

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Detailed Description

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.

High-Speed ADC Input

Driver Application

The MAX4434–MAX4437 op amps are ideal for drivin-

ghigh-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 stabil-

ity 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 noninvert-

ing configurations of the MAX4434–MAX4437 are shown

in Figure 2a and Figure 2b. The minimum uncondition-

ally stable gain values are 1 for the MAX4434/MAX4436

and 5 for the MAX4435/MAX4437. Use care in selecting

the value for the resistor marked RS in both circuits.

From dynamic stability considerations (based on the

part’s frequency response and the input capacitance of

the MAX4434–MAX4437), the maximum recommended

value for RS is 500Ω. In general, lower RS values will

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 RS value, take into consideration that the

current indicated as IF is supplied by the output stage and

must be discounted from the maximum output current to

calculate the maximum current available to the load. IF

can be found using the following equation:

IF = VIN(MAX)/RS

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 capacitance

associated with the feedback resistors must also be con-

sidered as a possible limitation to the available bandwidth

or to the dynamic stability. Only resistors with small paral-

lel capacitance specifications should be considered.

Applications Information

Layout and Power-Supply Bypassing

The MAX4434–MAX4437 have wide bandwidth and con-

sequently 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 bypass-

Figure 1. Typical Application Circuit

Figure 2b. Inverting Configuration

Figure 2a. Noninverting Configuration

HIGH-SPEED

14/16-BIT ADC

VCC

VEE

VOUT

VIN

A =

-RF

VOUT

VIN

VOUT

VIN

A = 1+

VOUT

VIN

MAX4434–MAX4437

Single-Supply, 150MHz, 16-Bit Accurate,

Ultra-Low Distortion Op Amps

www.maximintegrated.com

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