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EL2360

Triple 130MHz Current Feedback Amplifier

Intersil 

EL2360

can be easily modified by varying the value of the feedback

resistor. For example, by reducing RF to 430Ω, bandwidth

can be extended to 170MHz with under 1dB of peaking.

Further reduction of RF to 360Ω increases the bandwidth to

195MHz with about 2.5dB of peaking.

Bandwidth vs Temperature

Whereas many amplifier’s supply current and consequently

-3dB bandwidth drop off at high temperature, the EL2360

was designed to have little supply current variation with

temperature. An immediate benefit from this is that the -3dB

bandwidth does not drop off drastically with temperature.

With VS = ±15V and AV = +2, the bandwidth varies only from

150MHz to 110MHz over the entire die junction temperature

range of -50°C < T < 150°C.

Supply Voltage Range and Single Supply

Operation

The EL2360 has been designed to operate with supply

voltages from ±2V to ±15V. Optimum bandwidth, slew rate,

and video characteristics are obtained at higher supply

voltages. However, at ±2V supplies, the -3dB bandwidth at

AV = +2 is a respectable 70MHz. The following figure is an

oscilloscope plot of the EL2360 at ±2V supplies, AV = +2,

RF = RG = 560Ω, driving a load of 150Ω, showing a clean

±600mV signal at the output.

caused by a power dissipation differential (before and after

the voltage step). For AV = -1, due to the inverting mode

configuration, this tail does not appear since the input stage

does not experience the large voltage change as in the non-

inverting mode. With AV = -1, 0.01% settling time is slightly

greater than 100ns.

Power Dissipation

The EL2360 amplifier combines both high speed and large

output current capability at a moderate supply current in very

small packages. It is possible to exceed the maximum

junction temperature allowed under certain supply voltage,

temperature, and loading conditions. To ensure that the

EL2360 remains within it’s absolute maximum ratings, the

following discussion will help to avoid exceeding the

maximum junction temperature.

The maximum power dissipation allowed in a package is

determined according to [1]:

PDMAX

=

T----J---M-----A----X-----–-----T----A---M-----A----X--

θJA

where:

TJMAX = Maximum Junction Temperature

TAMAX = Maximum Ambient Temperature

θJA = Thermal Resistance of the Package

PDMAX = Maximum Power Dissipation in the Package

The maximum power dissipation actually produced by an IC

is the total quiescent supply current times the total power

supply voltage, plus the power in the IC due to the load, or

[2] :

PDMAX

=

N

×



 V S

×

ISMAX

+

(VS

–

VOUT)

×

-V----OR----UL----T--

If a single supply is desired, values from +4V to +30V can be

used as long as the input common mode range is not

exceeded. When using a single supply, be sure to either 1)

DC bias the inputs at an appropriate common mode voltage

and AC couple the signal, or 2) ensure the driving signal is

within the common mode range of the EL2360, which is

typically 1.5V from each supply rail.

Settling Characteristics

The EL2360 offers superb settling characteristics to 0.1%,

typically in the 35ns to 40ns range. There are no aberrations

created from the input stage which often cause longer

settling times in other current feedback amplifiers. The

EL2360 is not slew rate limited, therefore any size step up to

±10V gives approximately the same settling time.

As can be seen from the Long Term Settling Error curve, for

AV = +1, there is approximately a 0.035% residual which tails

away to 0.01% in about 40µs. This is a thermal settling error

where:

N =Number of amplifiers

VS = Total Supply Voltage

ISMAX = Maximum Supply Current per amplifier

VOUT = Maximum Output Voltage of the Application

RL = Load Resistance tied to Ground

If we set the two PDMAX equations, [1] and [2], equal to each

other, and solve for VS, we can get a family of curves for

various loads and output voltages according to [3]:

VS

=

-R---------L----------×--------(------T--------J--N----M--------×-A-------X--θ------J--–----A------T--------A--------M---------A-------X---------)----+-----(--V-----O----U----T----)--2-

(IS × RL) + VOUT

The figures below show total supply voltage VS vs RL for

various output voltage swings for the PDIP and SOIC

packages. The curves assume WORST CASE conditions of

TA = +85°C and IS = 11.3mA per amplifier. The curves do

11

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