8

Applications Information

Product Description

The EL5108 and EL5308 are fixed gain amplifiers that offer a

wide -3dB bandwidth of 450MHz and a low supply current of

3.5mA per amplifier. They work with supply voltages ranging

from a single 5V to 10V and they are also capable of

swinging to within 1.2V of either supply on the output. These

combinations of high bandwidth, low power, and high slew

rate make the EL5108 and EL5308 the ideal choice for many

low-power/high-bandwidth applications such as portable,

handheld, or battery-powered equipment.

For varying bandwidth and higher gains, consider the

EL5166 with 1GHz on a 9mA supply current or the EL5164

with 600MHz on a 3.5mA supply current. Versions include

single, dual, and triple amp packages with 6-pin SOT-23,

16-pin QSOP, and 8-pin or 16-pin SO outlines.

Power Supply Bypassing and Printed Circuit

Board Layout

As with any high frequency device, good printed circuit board

layout is necessary for optimum performance. Low

impedance ground plane construction is essential. Surface

mount components are recommended, but if leaded

components are used, lead lengths should be as short as

possible. The power supply pins must be well bypassed to

reduce the risk of oscillation. The combination of a 4.7µF

tantalum capacitor in parallel with a 0.01µF capacitor has

been shown to work well when placed at each supply pin.

Disable/Power-Down

The EL5108 and EL5308 amplifiers can be disabled and

placing their outputs in a high impedance state. When

disabled, the amplifier supply current is reduced to <25µA.

The EL5108 and EL5308 are disabled when the CE pin is

pulled up to within 1V of the positive 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 the amplifier will be enabled when CE is 2V or less, and

disabled when CE is above 4V. Although the logic levels are

not standard TTL, this choice of logic voltages allow the

EL5108 and EL5308 to be enabled by tying CE to ground,

even in 5V single supply applications. The CE pins can be

driven from CMOS outputs.

Gain Setting

The EL5108 and EL5308 are built with internal feedback and

gain resistors. The internal feedback resistors have equal

value; as a result, the amplifier can be configured into gain of

+1, -1, and +2 without any external resistors. Figure 21

shows the amplifier in gain of +2 configuration. The gain

error is ±2% maximum. Figure 22 shows the amplifier in gain

of -1 configuration. For gain of +1, IN+ and IN- should be

connected together as shown in Figure 23. This

configuration avoids the effects of any parasitic capacitance

on the IN- pin. Since the internal feedback and gain resistors

change with temperature and process, external resistor

should not be used to adjust the gain settings.

FIGURE 19. PACKAGE POWER DISSIPATION vs AMBIENT

TEMPERATURE

FIGURE 20. PACKAGE POWER DISSIPATION vs AMBIENT

TEMPERATURE

1

0.9

0.8

0.6

0.4

0.1

0

0

25

50

75

100

150

AMBIENT TEMPERATURE (°C)

125

85

JEDEC JESD51-3 LOW EFFECTIVE THERMAL

CONDUCTIVITY TEST BOARD

0.2

0.7

0.3

0.5

909mW

625mW

633mW

391mW

SO16 (0.150”)

SO8

QSOP16

SOT23-6

AMBIENT TEMPERATURE (°C)

0

0.4

1.4

1.2

1

0.8

0.6

0.2

0

25

50

75

100

150

125

85

JEDEC JESD51-7 HIGH EFFECTIVE THERMAL

CONDUCTIVITY TEST BOARD

0.1

1.250W

QSOP16

909mW

893mW

435mW

SO8

SOT23-6

SO16 (0.150”)

-

+

325

Ω

325

Ω

IN-

IN+

EL5108, EL5308