Ultra-High-Speed, Low-Distortion, Differential-

to-Single-Ended Line Receivers with Enable

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are

implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.

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Printed USA

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_______________Detailed Description

The MAX4444/MAX4445 differential-to-single-ended

line receivers offer high-speed and low-distortion per-

formance, and are ideally suited for video and RF sig-

nal-processing applications. These receivers offer a

small-signal bandwidth of 550MHz and have a high

slew rate of up to 5000V/µs. Their 120mA output capa-

bility allows them to be directly coupled to data acquisi-

tion systems.

__________Applications Information

Grounding Bypassing

Use the following high-frequency design techniques

when designing the PC board for the MAX4444/

MAX4445.

• Use a multilayer board with one layer dedicated as

the ground plane.

• Do not use wire wrap or breadboards due to high

inductance.

• Avoid IC sockets due to high parasitic capacitance

and inductance.

• Bypass supplies with a 0.1µF capacitor. Use sur-

face-mount capacitors to minimize lead inductance.

• Keep signal lines as short and straight as possible.

Do not make 90° turns. Use rounded corners. Do not

cross signal paths if possible.

• Ensure that the ground plane is free from voids.

Low-Power Enable Mode

The MAX4444/MAX4445 are disabled when EN goes

low. This reduces supply current to only 3.5mA. As the

output becomes higher impedance, the effective

impedance at the output for the MAX4444 is 1.8k

Ω. The

effective output impedance for the MAX4445 is 1.8k

Ω

plus RGAIN.

Setting Gain (MAX4445)

The MAX4445 is stable with a minimum gain configura-

tion of +2V/V. RGAIN, connected between the RG pins,

sets the gain of this device as shown in Figure 1.

Calculate the expected gain as follows:

Gain = (1 + 600 / RGAIN)

Driving Capacitive Loads

The MAX4444/MAX4445 are designed to drive capaci-

tive loads. However, excessive capacitive loads may

cause ringing or instability at the output as the phase

margin of the device reduces. Adding a small series

isolation resistor at the output helps reduce the ringing

but slightly increases gain error (Figure 2). For recom-

mended values, see

Typical Operating Characteristics.

Coaxial Line Driver

The MAX4444/MAX4445 are well suited to drive coaxial

cables. Their high output current capability can easily

drive the 75

Ω characteristic impedance of common

coaxial cables. Adjust the gain of the MAX4445 to com-

pensate for cable losses to maintain the required levels

at the input of the next stage.

Figure 1. Setting the Amplifier Gain

Figure 2. Using an Isolation Resistor for High Capacitive Loads

Chip Information

TRANSISTOR COUNT: 254

SUBSTRATE CONNECTED TO VEE

RGAIN

GAIN = 1 +

600

RGAIN

RG

RG

MAX4445

RISO

CLOAD

MAX4444

MAX4445

IN+

IN–