EL5234IY INTERSIL [Intersil Corporation], EL5234IY Datasheet - Page 11

• Manufacturer Part Number: EL5234IY
• Description: 650MHz, Gain of 5, Low Noise Amplifiers
• Manufacturer: INTERSIL [Intersil Corporation]

transfer function contribute to even higher closed loop
bandwidths. For example, the EL5134, EL5135, EL5234 and
EL5235 have a -3dB bandwidth of 650MHz at a gain of 5,
dropping to 150MHz at a gain of 10. It is important to note
that the EL5134, EL5135, EL5234 and EL5235 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 EL5134, EL5135, EL5234 and
EL5235 in a gain of only 5 exhibited 0.2dB of peaking with a
500Ω load.
Output Drive Capability
The EL5134, EL5135, EL5234 and EL5235 are designed to
drive a low impedance load. They can easily drive 6V
signal into a 500Ω load. This high output drive capability
makes the EL5134, EL5135, EL5234 and EL5235 and ideal
choice for RF, IF, and video applications. Furthermore, the
EL5134, EL5135, EL5234 and EL5235 are current-limited at
their outputs, allowing them 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 EL5134, EL5135, EL5234 and EL5235 are
designed to drive low impedance load, capacitive loads will
decreases the amplifiers’ 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 5Ω 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 EL5134 and EL5234 amplifiers can be disabled placing
their outputs in a high impedance state. When disable, each
amplifier current is reduced to 12uA. The EL5134 and
EL5234 are disabled when their CE pins are pulled up to
within 1V of the power suply. Similarly, the amplifiers are
enabled by floating or pulling its CE pin to at least 3V below
the positive supply. For +/-5V supply, this means that
EL5134 and EL5234 amplifiers will be enabled when CE is
2V or less, and disabled when CE is above 4V. Although the
logic levels are not stardard TTL, this choice of logic
voltages allows the EL5134 and EL5234 to be enabled by
typing CE to ground, even in 5V single supply applications.
The CE pin can be driveing from CMOS outputs.
Supply Voltage Range and Single-Supply
Operation
The EL5134, EL5135, EL5234 and EL5235 have been
designed to operate with supply voltages having a span of
greater than 5V and less than 12V. In practical terms, this
means that they will operate on dual supplies ranging from
11
EL5134, EL5135, EL5234, EL5235
P-P
±2.5V to ±6V. With single-supply, the EL5134, EL5135,
EL5234 and EL5235 will operate from 5V to 12V. To prevent
internal circuit latch-up, the slew rate between the negative
and positve supplies must be less than 1V/nS.
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
EL5134, EL5135, EL5234 and EL5235 have an input range
which extends to within 2V of either supply. So, for example,
on ±5V supplies, the EL5134, EL5135, EL5234 and EL5235
have an input range which spans ±3V. The output range of
the EL5134, EL5135, EL5234 and EL5235 is also quite
large, extending to within 2V of the supply rail. On a ±5V
supply, the output is therefore capable of swinging from
-3.1V to +3.1V. Single-supply output range is larger because
of the increased negative swing due to the external pull-
down resistor to ground.
Power Dissipation
With the wide power supply range and large output drive
capability of the EL5134, EL5135, EL5234 and EL5235, it is
possible to exceed the 150°C maximum junction
temperatures under certain load and power-supply
conditions. It is therefore important to calculate the
maximum junction temperature (T
to determine if power supply voltages, load conditions, or
package type need to be modified for the EL5134, EL5135,
EL5234 and EL5235 to remain in the safe operating area.
These parameters are related as follows:
where:
• P
• PD
where:
• T
• θ
• PD
• V
• I
• V
• R
Power Supply Bypassing And Printed Circuit
Board Layout
As with any high frequency devices, good printed circuit
board layout is essential for optimum performance. Ground
dissipation of each amplifier in the package (PD
application
MAX
PD
JA
DMAXTOTAL
MAX
S
OUTMAX
L
MAX
MAX
= Load resistance
= Supply voltage
= Thermal resistance of the package
MAX
= Maximum supply current of 1 amplifier
= Maximum ambient temperature
for each amplifier can be calculated as follows:
= Maximum power dissipation of 1 amplifier
=
T
JMAX
= Maximum output voltage swing of the
2*V
is the sum of the maximum power
S
=
×
I
T
SMAX
MAX
+
+
(
(
θ
V
JA
S
xPD
- V
JMAX
OUTMAX
MAXTOTAL
) for all applications
)
×
V
--------------------------- -
)
OUTMAX
MAX
March 9, 2006
R
L
FN7383.3
)