el5197a Intersil Corporation, el5197a Datasheet - Page 13

• Manufacturer Part Number: el5197a
• Description: Single 200mhz Fixed Gain Amplifier With Enable
• Manufacturer: Intersil Corporation

Applications Information
Product Description
The EL5197 is a fixed gain amplifier that offers a wide -3dB
bandwidth of 200MHz and a low supply current of 4mA. The
EL5197 works with supply voltages ranging from a single 5V
to 10V and they are also capable of swinging to within 1V of
either supply on the output. This combination of high
bandwidth and low power, together with aggressive pricing
make the EL5197 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 EL5191
with 1GHz on a 9mA supply current or the EL5193 with
300MHz on a 4mA supply current. Versions include single,
dual, and triple amp packages with 5 Ld SOT-23, 16 Ld QSOP,
and 8 Ld or 16 Ld SOIC 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 EL5197A amplifier can be disabled placing its output in
a high impedance state. When disabled, the amplifier supply
current is reduced to < 150µA. The EL5197A is disabled
when its 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 an EL5197A 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 allows the EL5197A to be
enabled by tying CE to ground, even in 5V single supply
applications. The CE pin can be driven from CMOS outputs.
Gain Setting
The EL5197A is 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 1 shows the
amplifier in gain of +2 configuration. The gain error is ±2%
maximum. Figure 2 shows the amplifier in gain of -1
configuration. For gain of +1, IN+ and IN- should be
connected together as shown in Figure 3. This configuration
avoids the effects of any parasitic capacitance on the IN- pin.
Since the internal feedback and gain resistors change with
13
EL5197, EL5197A
temperature and process, external resistor should not be
used to adjust the gain settings.
Supply Voltage Range and Single-Supply
Operation
The EL5197 has been designed to operate with supply
voltages having a span of greater than or equal to 5V and
less than 11V. In practical terms, this means that the EL5197
will operate on dual supplies ranging from ±2.5V to ±5V. With
single-supply, the EL5197 will operate from 5V to 10V.
As supply voltages continue to decrease, it becomes
necessary to provide input and output voltage ranges that
can get as close as possible to the supply voltages. The
EL5197 has an input range which extends to within 2V of
either supply. So, for example, on ±5V supplies, the EL5197
has an input range which spans ±3V. The output range of the
EL5197 is also quite large, extending to within 1V of the
supply rail. On a ±5V supply, the output is therefore capable
of swinging from -4V to +4V. Single-supply output range is
larger because of the increased negative swing due to the
IN+
IN-
IN-
IN-
400
FIGURE 3. A
FIGURE 1. A
FIGURE 2. A
400
IN+
400
IN+
+
-
400
V
V
+
-
V
400
+
= +1
-
= +2
400
= -1
May 16, 2007
FN7184.2