10

FN7382.8

May 4, 2007

Applications Information

Product Description

The EL5132, EL5133 is a voltage feedback operational

amplifier designed for communication and imaging

applications requiring very low voltage and current noise. It

also features low distortion while drawing moderately low

supply current and is built on Intersil's proprietary high-speed

complementary bipolar process. The EL5132, EL5133 uses

a classical voltage-feedback topology which allows them to

be used in a variety of applications where current-feedback

amplifiers are not appropriate because of restrictions placed

upon the feedback element used with the amplifier.

Gain-Bandwidth Product and the -3dB Bandwidth

The EL5132, EL5133 has a gain-bandwidth product of

3000MHz while using only 11mA of supply current. For gains

greater than 10, their closed-loop -3dB bandwidth is

approximately equal to the gain-bandwidth product divided

by the noise gain of the circuit. For gains of 10, higher-order

poles in the amplifiers' transfer function contribute to even

higher closed loop bandwidths. For example, the EL5132,

EL5133 have a -3dB bandwidth of 670MHz at a gain of 10,

dropping to 150MHz at a gain of 30. It is important to note

that the EL5132, EL5133 is designed so that this “extra”

bandwidth in low-gain application does not come at the

expense of stability. As seen in the typical performance

curves, the EL5132, EL5133 in a gain of only 10 exhibited

0.5dB of peaking with a 500

Ω load.

Output Drive Capability

The EL5132 and EL5133 are is designed to drive a low

load. This high output drive capability makes the EL5132,

EL5133 an ideal choice for RF, IF, and video applications.

Furthermore, the EL5132, EL5133 is current-limited at the

output, allowing it to withstand momentary short to ground.

However, the power dissipation with output-shorted cannot

exceed the power dissipation capability of the package.

Driving Cables and Capacitive Loads

Although the EL5132, EL5133 is designed to drive low

impedance load, capacitive loads will decreases the

amplifier's phase margin. As shown in the performance

curves, capacitive load can result in peaking, overshoot and

possible oscillation. For optimum AC performance,

capacitive loads should be reduced as much as possible or

isolated with a series resistor between 5

Ω to 20Ω. When

driving coaxial cables, double termination is always

recommended for reflection-free performance. When

properly terminated, the capacitance of the coaxial cable will

not add to the capacitive load seen by the amplifier.

Disable/Power-Down

The EL5132 amplifier can be disabled placing its output in a

high impedance state. When disable, the amplifier current is

reduced to 12µA. The EL5132 is disabled when it CE pin is

pulled up to within 1V of the power supply. Similarly, the

amplifier is enabled by floating or pulling its CE pin to at least

3V below the positive supply. For ±5V supply, this means

that an EL5132 amplifier will be enabled when CE is 2V or

FIGURE 35. DIFFERENTIAL GAIN (%)

FIGURE 36. DIFFERENTIAL PHASE (°)

0.2

0

010

0.1

-0.05

0.0

-0.15

-0.20

20

30

40

50

60

70

80

90

100

0.20

0

010

0.15

-0.05

0.05

-0.15

-0.20

20

30

40

50

60

70

80

90

100

EL5132, EL5133