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

Op Amps with Rail-to-Rail Outputs and Disable

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11

have a 16ns settling time to 0.1%, 485V/µs slew rates,

and output-current-drive capability of up to 75mA

making them ideal for driving video loads.

Inverting and Noninverting Configurations

resistor values to fit your application. Large resistor val-

ues increase voltage noise and interact with the ampli-

fier’s input and PC board capacitance. This can

generate undesirable poles and zeros and decrease

bandwidth or cause oscillations. For example, a nonin-

Ω

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

bandwidth, it jeopardizes stability. Reducing the 1k

Ω

resistors to 100

Ω extends the pole frequency to

1.59GHz, but could limit output swing by adding 200

Ω

in parallel with the amplifier’s load resistor

(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

0.1µF capacitor as close to the pin as possible. If operat-

ing with dual supplies, bypass each supply with a 0.1µF

capacitor.

Maxim recommends using microstrip and stripline

techniques to obtain full bandwidth. To ensure that the

PC board does not degrade the amplifier’s perfor-

mance, design it for a frequency greater than 1GHz.

Pay careful attention to inputs and outputs to avoid

large parasitic capacitance. Whether or not you use a

constant-impedance board, observe the following

design guidelines:

• Don’t use wire-wrap boards; they are too inductive.

• Don’t use IC sockets; they increase parasitic capaci-

tance and inductance.

• Use surface-mount instead of through-hole compo-

nents for better high-frequency performance.

• Use a PC board with at least two layers; it should be

as free from voids as possible.

• Keep signal lines as short and as straight as possi-

ble. Do not make 90° turns; round all corners.

Rail-to-Rail Outputs,

Ground-Sensing Inputs

For +5V single-supply operation, the input common-

- 2.25V) with excellent common-mode rejection.

Beyond this range, the amplifier output is a nonlinear

function of the input, but does not undergo phase

reversal or latchup.

For ±5V dual-supply operation, the common-mode

For +5V single-supply operation the output swings to

within 50mV of either power-supply rail with a 2k

Ω

load. The input ground sensing and the rail-to-rail out-

put substantially increase the dynamic range. With a

symmetric input in a single +5V application, the input

can swing 2.95Vp-p and the output can swing 4.9Vp-p

with minimal distortion.

Low-Power Disable Mode

The disable feature (DISABLE_) allows the amplifier to

be placed in a low-power, high-output-impedance

state. When the disable pin (DISABLE_) is active, the

amplifier’s output impedance is 35k

Ω. This high resis-

tance and the low 2pF output capacitance make the

MAX4380–MAX4382 and the MAX4384 ideal in

RF/video multiplexer or switch applications. For larger

arrays, pay careful attention to capacitive loading.

Refer to the Output Capacitive Loading and Stability

section.

IN

MAX438 _

Figure 1b. Inverting Gain Configuration

IN

MAX438 _

Figure 1a. Noninverting Gain Configuration