EL5166ISZ-T13 Intersil, EL5166ISZ-T13 Datasheet - Page 10

• Manufacturer Part Number: EL5166ISZ-T13
• Description: IC AMP CFA SGL 1.4GHZ 8-SOIC
• Manufacturer: Intersil

Specifications of EL5166ISZ-T13

• Amplifier Type: Current Feedback
• Number Of Circuits: 1
• Slew Rate: 6000 V/µs
• -3db Bandwidth: 1.4GHz
• Current - Input Bias: 8.5µA
• Voltage - Input Offset: 500µV
• Current - Supply: 8.5mA
• Current - Output / Channel: 200mA
• Voltage - Supply, Single/dual (±): 5 V ~ 12 V, ±2.5 V ~ 6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Output Type: -
• Gain Bandwidth Product: -

Applications Information
Product Description
The EL5166 and EL5167 are current-feedback operational
amplifiers that offers a wide -3dB bandwidth of 1.4GHz and a
low supply current of 8.5mA per amplifier. The EL5166 and
EL5167 work 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. Because of their current-feedback
topology, the EL5166 and EL5167 do not have the normal
gain-bandwidth product associated with voltage-feedback
operational amplifiers. Instead, their -3dB bandwidth remains
relatively constant as closed-loop gain is increased. This
combination of high bandwidth and low power, together with
aggressive pricing make the EL5166 and EL5167 ideal
choices for many low-power/high-bandwidth applications,
such as portable, handheld, or battery-powered equipment.
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.
For good AC performance, parasitic capacitance should be
kept to a minimum, especially at the inverting input (see
“Capacitance at the Inverting Input” on page 10). Even when
ground plane construction is used, it should be removed
from the area near the inverting input to minimize any stray
capacitance at that node. Carbon or Metal-Film resistors are
acceptable with the Metal-Film resistors giving slightly less
peaking and bandwidth because of additional series
inductance. Use of sockets, particularly for the SO package,
should be avoided if possible. Sockets add parasitic
inductance and capacitance, which will result in additional
peaking and overshoot.
Disable/Power-Down
The EL5166 amplifier can be disabled, placing its output in a
high impedance state. When disabled, the amplifier supply
current is reduced to 13µA. The EL5166 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 EL5166 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 EL5166 to be enabled by tying CE
to ground, even in 5V single supply applications. The CE pin
can be driven from CMOS outputs.
10
EL5166, EL5167
Capacitance at the Inverting Input
Any manufacturer’s high-speed voltage- or current-feedback
amplifier can be affected by stray capacitance at the
inverting input. For inverting gains, this parasitic capacitance
has little effect because the inverting input is a virtual
ground. But for non-inverting gains, this capacitance (in
conjunction with the feedback and gain resistors) creates a
pole in the feedback path of the amplifier. This pole, if low
enough in frequency, has the same destabilizing effect as a
zero in the forward open-loop response. The use of large
value feedback and gain resistors exacerbates the problem
by further lowering the pole frequency (increasing the
possibility of oscillation).
The EL5166 and EL5167 frequency responses are
optimized with the resistor values in Figure 3. With the high
bandwidth of these amplifiers, these resistor values might
cause stability problems when combined with parasitic
capacitance, thus ground plane is not recommended around
the inverting input pin of the amplifier.
Feedback Resistor Values
The EL5166 and EL5167 have been designed and specified
at a gain of +2 with R
feedback resistor gives 800MHz of -3dB bandwidth at A
with about 0.5dB of peaking. Since the EL5166 and EL5167
are current-feedback amplifiers, it is also possible to change
the value of R
of Frequency Response for Various R
“Typical Performance Curves” on page 4, bandwidth and
peaking can be easily modified by varying the value of the
feedback resistor.
Because the EL5166 and EL5167 are current-feedback
amplifiers, their gain-bandwidth product is not a constant for
different closed-loop gains. This feature actually allows the
EL5166 and EL5167 to maintain a reasonably constant -3dB
bandwidth for different gains. As gain is increased,
bandwidth decreases slightly while stability increases. Since
the loop stability is improving with higher closed-loop gains,
it becomes possible to reduce the value of R
specified 250Ω and still retain stability, resulting in only a
slight loss of bandwidth with increased closed-loop gain.
Supply Voltage Range and Single-Supply
Operation
The EL5166 and EL5167 have been designed to operate
with supply voltages having a span of greater than 5V and
less than 10V. In practical terms, this means that the EL5166
and EL5167 will operate on dual supplies ranging from
±2.5V to ±5V. With single-supply, they 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
EL5166 and EL5167 have an input range that extends to
within 1.8V of either supply. So, for example, on ±5V
F
to get more bandwidth. As seen in the curve
F
approximately 392Ω. This value of
F
and R
F
G
September 14, 2010
below the
in the
FN7365.6
V
= 2