MAX4451 查看數據表（PDF） - Maxim Integrated

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MAX4451

Ultra-Small, Low-Cost, 210MHz, Single-Supply Op Amps with Rail-to-Rail Outputs

Maxim Integrated 

Ultra-Small, Low-Cost, 210MHz, Single-Supply

Op Amps with Rail-to-Rail Outputs

Pin Description

PIN

MAX4450 MAX4451

1

—

2

4

3

—

4

—

5

8

—

1

—

2

—

3

—

7

—

6

—

5

NAME

FUNCTION

OUT

VEE

IN+

IN-

VCC

OUTA

INA-

INA+

OUTB

INB-

INB+

Amplifier Output

Negative Power Supply

or Ground (in single-

supply operation)

Noninverting Input

Inverting Input

Positive Power Supply

Amplifier A Output

Amplifier A Inverting

Input

Amplifier A Noninverting

Input

Amplifier B Output

Amplifier B Inverting

Input

Amplifier B Noninverting

Input

Detailed Description

The MAX4450/MAX4451 are single-supply, rail-to-rail,

voltage-feedback amplifiers that employ current-feed-

back techniques to achieve 485V/µs slew rates and

210MHz bandwidths. Excellent harmonic distortion and

differential gain/phase performance make these ampli-

fiers an ideal choice for a wide variety of video and RF

signal-processing applications.

The output voltage swings to within 55mV of each sup-

ply rail. Local feedback around the output stage

ensures low open-loop output impedance to reduce

gain sensitivity to load variations. The input stage per-

mits common-mode voltages beyond the negative sup-

ply and to within 2.25V of the positive supply rail.

Applications Information

Choosing Resistor Values

Unity-Gain Configuration

The MAX4450/MAX4451 are internally compensated for

unity gain. When configured for unity gain, the devices

require a 24Ω resistor (RF) in series with the feedback

path. This resistor improves AC response by reducing

the Q of the parallel LC circuit formed by the parasitic

feedback capacitance and inductance.

Inverting and Noninverting Configurations

Select the gain-setting feedback (RF) and input (RG)

resistor values to fit your application. Large resistor val-

ues increase voltage noise and interact with the amplifi-

er’s input and PC board capacitance. This can

generate undesirable poles and zeros and decrease

bandwidth or cause oscillations. For example, a nonin-

verting gain-of-two configuration (RF = RG) using 1kΩ

resistors, combined with 1pF of amplifier input capaci-

tance and 1pF of PC board capacitance, causes a pole

at 159MHz. Since this pole is within the amplifier band-

width, it jeopardizes stability. Reducing the 1kΩ resis-

tors to 100Ω extends the pole frequency to 1.59GHz,

but could limit output swing by adding 200Ω in parallel

with the amplifier’s load resistor. Table 1 lists suggest-

ed feedback and gain resistors, and bandwidths for

several gain values in the configurations shown in

Figures 1a and 1b.

Layout and Power-Supply Bypassing

These amplifiers operate from a single +4.5V to +11V

power supply or from dual ±2.25V to ±5.5V supplies. For

single-supply operation, bypass VCC to ground with a

RG

RF

RTO

MAX445 _

IN

VOUT = [1+ (RF / RG)] VIN

RTIN

VOUT

RO

Figure 1a. Noninverting Gain Configuration

RG

RF

IN

RTIN

RTO

MAX445 _

VOUT = -(RF / RG) VIN

RS

VOUT

RO

Figure 1b. Inverting Gain Configuration

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