EL2176CS - Intersil Corporation

FN7054

CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.

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EL2176, EL2276

70MHz/1mA Current Mode Feedback Amp

w/Disable The EL2176/EL2276 are single/dual

current-feedback operational

amplifiers which achieve a -3dB

bandwidth of 70MHz at a gain of +1 while consuming only

1mA of supply current per amplifier. They will operate with

dual supplies ranging from ±1.5V to ±6V, or from single

supplies ranging from +3V to +12V. The EL2176/EL2276

also include a disable/power-down feature which reduces

current consumption to 0mA while placing the amplifier

output in a high impedance state. In spite of its low supply

current, the EL2276 can output 55mA while swinging to ±4V

on ±5V supplies. The EL2176 can output 100mA with similar

output swings. These attributes make the EL2176/EL2276

excellent choices for low power and/or low voltage cable-

driver, HDSL, or RGB applications.

For Single, Dual and Quad applications without disable,

consider the EL2170 (8-Pin Si ngle), EL2270 (8-Pin Dual) or

EL2470 (14-Pin Quad). For higher bandwidth applications

where low power is still a concern, consider the

EL2180/EL2186 family which also comes in similar Single,

Dual and Quad configurations. The EL2180/EL2186 family

provides a -3dB bandwidth of 250MHz while consuming

3mA of supply curren t pe r amp l i fi e r.

Features

• Single (EL2176) and dual (EL2276) topologies

• 1mA supply current (per amplifier)

• 70MHz -3dB bandwidth

• Low cost

• Fast disable

• Powers down to 0mA

• Single- and dual-supply operation down to ±1.5V

• 0.15%/0.15° diff. gain/diff. phase into 150Ω

• 800V/µs slew rate

• Large output drive current:

100mA (EL2176)

55mA (EL2276)

• Also available without disable in single (EL2170), dual

(EL2270) and quad (EL2470)

• Higher speed EL2180/EL2186 family also available (3mA/

250MHz) in single, dual and quad

Applications

• Low power/battery applica tio ns

• HDSL amplifiers

• Video amplifiers

• Cable drivers

• RGB amplifiers

• Test equipment amplifiers

• Current to voltage conver ters

Ordering Information

PART NUMBER TEMP. RANGE PACKAGE PKG. NO.

EL2176CN -40°C to +85°C 8-Pin PDIP MDP0031

EL2176CS -40°C to +85°C 8-Pin SOIC MDP0027

EL2276CN -40°C to +85°C 14-Pin PDIP MDP0031

EL2276CS -40°C to +85°C 14-Pin SOIC MDP0027

Pinouts EL2176

(8-PIN SO, PDIP)

TOP VIEW

EL2276

(14-PIN SO, PDIP)

TOP VIEW

Manufactured under U.S. Patent No. 5,352,989, 5,351,012, 5,418,495

Data Sheet December 1995, Rev. B

Absolute Maximum Ratings (TA = 25°C)

Voltage between VS+ and VS-. . . . . . . . . . . . . . . . . . . . . . . . +12.6V

Common-Mode Input Voltage . . . . . . . . . . . . . . . . . . . . . VS- to VS+

Differential Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .±6V

Current into +IN or -IN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .±7.5mA

Internal Power Dissipation . . . . . . . . . . . . . . . . . . . . . . . See Curves

Operating Ambient Temperature Range . . . . . . . . . .-40°C to +85°C

Operating Junction Temperature Plastic Packages . . . . . . . . . 150°C

Output Current (EL2176). . . . . . . . . . . . . . . . . . . . . . . . . . . ±120mA

Output Current (EL2276). . . . . . . . . . . . . . . . . . . . . . . . . . . . ±60mA

Storage Temperature Range . . . . . . . . . . . . . . . . . .-65°C to +150°C

CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the

device at these or any other conditi ons above those indicated in the operational sections of this specification is not implied.

IMPORTANT NOTE: All parameters having Min/Max specifications are guaranteed. Typical values are for information purposes only. Unless otherwise noted, all tests

are at the specified temperature and are pulsed tests, therefore: TJ = TC = TA

DC Electrical Specificat ions VS = ±5V, RL = 150Ω, ENABLE = 0V, TA = 25°C unless otherwise specified.

PARAMETER DESCRIPTION CONDITIONS MIN TYP MAX UNITS

VOS Input Offset Voltage 2.5 15 mV

TCVOS Average Input Offset Voltage Drift Measured from TMIN to TMAX 5µV/°C

dVOS VOS Matching EL2276 only 0.5 mV

+IIN + Input Current 0.5 5 µA

d+IIN +IIN Matching EL2276 only 20 nA

-IIN - Input Current 415µA

d-IIN -IIN Matching EL2276 only 1.5 µA

CMRR Common Mode Rejection Ratio VCM = ±3.5 V 45 50 dB

-ICMR - Input Current Common Mode Rejection VCM = ±3.5V 4 10 µA/V

PSRR Power Supply Rejection Ratio VS is moved from ±4V to ±6V 60 70 dB

-IPSR - Input Current Power Supply Rejection VS is moved from ±4V to ±6V 0.5 5 µA/V

ROL Transimpedance VOUT = ±2.5V 150 400 kΩ

+RIN + Input Resistance VCM = ±3.5V 1 4 MΩ

+CIN + Input Capacitance 1.2 pF

CMIR Common Mode Input Range ±3.5 ±4.0 V

VOOutput Voltage Swing VS = ±5 ±3.5 ±4.0 V

VS = +5 Single-Supply, High 4.0 V

VS = +5 Single-Supply, Low 0.3 V

IOOutput Current EL2176 only 80 100 mA

EL2276 only, per Amplifier 50 55 mA

ISSupply Current ENABLE = 2.0V, per Amplifier 1 2 mA

IS(DIS) Supply Current (Disabled) ENABLE = 4.5V 0 20 µA

COUT(DIS) Output Capacitance (Disabled) ENABLE = 4.5V 4.4 pF

REN Enable Pin Input Resistance Measured at ENABLE = 2.0V, 4.5V 45 85 kΩ

IIH Logic “1” Input Current Measured at ENABLE, ENABLE = 4.5V -0.04 µA

IIL Logic “0” Input Current Measured at ENABLE, ENABLE = 0V -53 µA

VDIS Minimum Voltage at ENABLE to Disable 4.5 V

VEN Maximum Voltage at ENABLE to Enable 2.0 V

EL2176, EL2276

AC Electrical Specifications VS = ±5V, RF = RG = 1.0kΩ, RL = 150Ω, ENABLE = 0V, TA = 25°C unless otherwise specified.

PARAMETER DESCRIPTION CONDITIONS MIN TYP MAX UNITS

-3dB BW -3dB Bandwidth AV = +1 70 MHz

-3dB BW -3dB Bandwidth AV = +2 60 MHz

SR Slew Rate VOUT = ±2.5V, AV = +2 400 800 V/µs

tR, tFRise and Fall Time VOUT = ±500mV 4.5 ns

tPD Propagation Delay VOUT = ±50mV 4.5 ns

OS Overshoot VOUT = ±500mV 3.0 %

ts 0.1% Settling VOUT = ±2.5V, AV = -1 40 ns

dG Differential Gain AV = +2, RL = 150Ω (Note 1) 0.15 %

dP Differential Phase AV = +2, RL = 150Ω (Note 1) 0.15 °

dG Differential Gain AV = +1, RL = 500Ω (Note 1) 0.02 %

dP Differential Phase AV = +1, RL = 500Ω (Note 1) 0.01 °

tON Turn-On Time AV = +2, VIN = +1V, RL = 150Ω (Note 2) 40 100 ns

tOFF Turn-Off Time AV = +2, VIN = +1V, RL = 150Ω (Note 2) 1500 2000 ns

CS Channel Separation EL2276 only, f = 5MHz 85 dB

NOTES:

1. DC offset from 0V to 0.714V, AC amplitude 286mVP-P, f = 3.58MHz.

2. Measured from the application of the logic signal until the output voltage is at the 50% point between initial and final values.

EL2176, EL2276

Test Circuit (per Amplifier)

Simplified Schematic (per Amplifier)

EL2176, EL2276

Typical Performance Curves

Non-Inverting

Frequency Response (Gain) Non-Inverting

Frequency Response (Phase) Frequency Response for

Various RF and RG

Inverting Frequency

Response (Gain)

Transimpedance (ROL) PSRR and CMRR Frequency Response

for Various CIN-

Frequency Response for

Various RL and CL

Inverting Frequency

Response (Phase)

EL2176, EL2276

Typical Performance Curves (Continued)

Voltage and Current

Noise vs Frequency 2nd and 3rd Harmonic

Distortion vs Frequency Output Voltage

vs Frequency

Output Voltage Swing

vs Supply Voltage

-3dB Bandwidth and Peaking

vs Supply Voltage for

Various Inverting Gains

-3dB Bandwidth and Peaking

vs Supply Voltage for

Various Non-In verting Gains

Supply Current vs Supply

Voltage Common-Mode Input Range

vs Supply Voltage Slew Rate vs

Supply Voltage

EL2176, EL2276

Typical Performance Curves (Continued)

Input Bias Current vs

Die Temperature Short-Circuit Current vs

Die Temperature Transimpedance (ROL) vs

Die Temperature

-3dB Bandwidth and Peaking

vs Die Temperature for

Various Non-Inverting Gains

-3dB Bandwidth and Peaking

vs Die Temperature for

Various Inverting Gains Input Offset Voltage

vs Die Temperature

Supply Current vs

Die Temperature Input Voltage Range vs

Die Temperature Slew Rate vs

Die Temperature

EL2176, EL2276

Typical Performance Curves (Continued)

Differential Gain and

Phase vs DC Input Voltage

at 3.58MHz/AV = +2

Differential Gain and

Phase vs DC Input Offset

at 3.58MHz/AV = +1

Settling Time vs

Settling Accuracy

Large-Signal Step Response

8-Pin Plastic DIP

Maximum Power Dissipation

vs Ambient Temperature

8-Pin SO

Maximum Power Dissipation

vs Ambient Temperature

Small-Signal Step Response

14-Pin Plastic DIP

Maximum Power Dissipation

vs Ambient Temperature

14-Pin SO

Maximum Power Dissipation

vs Ambient Temperature Channel Separation

vs Frequency (EL227 6)

EL2176, EL2276

Applications Information

Product Description

The EL2176/EL2276 are current-feedback operational

amplifiers that offer a wide -3dB bandwidth of 70MHz, a low

supply current of 1mA per amplifier and the ability to disable

to 0mA. Both products also feature high output current drive .

The EL2176 can output 100mA, while the EL2276 can

output 55mA per amplifier. The EL2176/EL2276 work with

supply voltages ranging from a single 3V to ±6V, and they

are also capable of s winging to with in 1V of either supply on

the input and the output. Beca use of their current-feedback

topology, the EL2176/EL2276 do not have the normal gain-

bandwidth product associated with voltage-feedback

operational amplifiers. This allows their -3dB bandwidth to

remain relatively constant as closed-loop gain is increased.

This combination of high bandwidth and low power, together

with aggressive pricing make the EL2176/EL2276 the ideal

choice for many low-power/high-bandwidth applications such

as portable computing, HDSL, and video processing.

For Single, Dual and Quad applications without disable,

consider the EL2170 (8-Pin Si ngle), EL2270 (8-Pin Dual)

and EL2470 (14-Pin Quad). If more AC performance is

required, refer to the EL2180/EL2186 family which provides

Singles, Duals, and Quads with 250MHz of bandwidth while

consuming 3mA of supply current per amplifier.

Power Supply Bypassing and Printed Circuit

Board Layout

As with any high-frequency device, good printed circuit

board lay out is necessary for optimum perf ormance. Ground

plane construction is highly recommended. 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

0.1µF capacitor has been shown to work well when placed at

each suppl y pin.

For good AC performance, parasitic capacitance sh ould be

kept to a minimum especially at the inverting input (see the

Capacitance at the Inverting Input section). Ground plane

construction should be used, but it should be removed from

the area near the inverting input to minimize any str ay

capacitance at that node. Carbon or Metal-Film resistors are

acceptable with the Metal-Film resistors giving slightly less

peaking and bandwidth because of their 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 some

additional peaking and overshoot.

Disable/Power-Down

The EL2176/EL2276 amplifiers can be disabled, placing

their output in a high-impedance state. When disabled, each

amplifier's supply current is reduced to 0mA. Each

EL2176/EL2276 amplifier is disabled when its ENABLE pin

is floating or pulled up to within 0.5V of the positive supply.

Similarly, each amplifier is enabled by pulling its ENABLE pin

at least 3V below the positive supply. For ±5V supplies, this

means that an EL2176/EL2276 amplifier will be enabled

when ENABLE is at 2V or less, and disabled when ENABLE

is above 4.5V. Although the logic levels are not standard

TTL, this choice of logic voltages allows the EL2176/EL2276

to be enabled by tying ENABLE to ground, even in +3V

single-supply applications. The ENABLE pin can be driven

from CMOS outputs or open-collector TTL.

When enabled, supply current does var y somewhat with the

voltage applied at ENABLE. For example, with the supply

voltages of the EL2176 at ±5V, if ENABLE is tied to -5V

(rather than ground) the supply current will increase about

15% to 1.15mA.

Capacitance at the Inverting Input

Any manufacturer's high-speed voltage- or current-feedbac k

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 virtua l

ground, but for non-inverting gains this capacitance (in

conjunction with the f eedbac k and gain resistors) creates a

pole in the feedback path of the amplifier. This pol e, 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 further exacerbates the

problem by further lowering the pol e frequency.

The EL2176/EL2276 have been specially designed to

reduce power dissipation in the feedback network by using

large 1.0kΩ feedback and gain resistors. With the high

bandwidths of these amplifiers, these large resistor values

would normally cause stability problems when combined

with parasitic capacitance, but by interna lly canceling the

effects of a nominal amount of parasitic capacitance, the

EL2176/EL2276 remain very stable. For less e xperienced

users, this f eature makes the EL2176/EL2276 much more

f orgiving, and therefore easier to use than other products not

incorporating th is p r op riet ary circuitry.

The experienced user with a large amount of PC board

layout experience may find in rare cases that the

EL2176/EL2276 have less bandwidth than expected. In this

case, the in v erting input may hav e less parasitic capacitance

than expected by the internal compensation circuitry of the

EL2176/EL2276. The reduction of feedback resistor values

(or the addition of a very small amount of external

capacitance at the inverting input, e.g., 0.5pF) will increase

bandwidth as desired. Please see the curves fo r Frequency

EL2176, EL2276

Response for Various RF and RG, and F requency Response

for Various CIN-.

Feedback Resistor Values

The EL2176/EL 2276 have been designed and specified at

gains of +1 and +2 with RF = 1.0kΩ. This value of feedback

resistor gives 70MHz of -3dB bandwidth at AV = +1 with

about 1.5dB of peaking, and 60MHz of -3dB bandwidth at A V

= +2 with about 0.5dB of peaking. Since the EL2176/EL2276

are current-f eedbac k amplifiers, it is also possible to change

the value of RF to get more bandwidth. As seen in the curve

of Frequency Response For Various RF and RG, bandwidth

and peaking can be easily modified by varying the value of

the feedback resistor.

Because the EL2176 is a current-feedback amplifier, the

gain-bandwidth product is not a constant for different closed-

loop gains. This feature actually allows the EL217 6/EL2276

to maintain about the same -3dB bandwidth, regardless of

closed-loop gain. Howe ver, as closed-loop gain is increased,

bandwidth decreases slightly while stability increases.

Since the loop stability is improving with higher clo se d-loop

gains, it becomes possible to reduce the value of RF belo w

the specified 1.0kΩ and still retain stability, resulting in only a

slight loss of bandwidth with increased close d-loop gain.

Supply Voltage Range and Single-Supply

Operation

The EL2176/EL 2276 have been designed to operate with

supply voltages having a span of greater than 3V, and less

than 12V. In practical terms, this means that the

EL2176/EL2276 will operate on dual supplies ranging from

±1.5V to ±6V. With a single-supply, the EL2176 will operate

from +3V to +12V.

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

EL2176/EL2276 have an input v oltage range that ex tends to

within 1V of either supply. So , for example, on a single +5V

supply, the EL2176/EL2276 have an input range which

spans from 1V to 4V. The output range of the

EL2176/EL2276 is also quite large, e xtending to within 1V of

the supply rail. On a ±5V supply, the output is therefore

capable of swinging from -4V to +4V. Single-supply ou tput

range is even larger because of the increased negative

swing due to the external pull-down resistor to ground. On a

single +5V supply, output voltage range is about 0.3V to 4V.

Video Performance

For good video performance, an amplifier is required to

maintain the same output impedance and the same

frequency response as DC le v els are changed at the output.

This is especially difficult when driving a standard video load

of 150Ω, because of the change in output current with DC

level. Until the EL2176/EL2276, good Diff erential Gain could

only be achiev ed by running high idle currents through the

output transistors (to reduce variations in output impedance).

These currents were typically in excess of the entire 1mA

supply current of each EL2176/EL2276 amplifier! Special

circuitr y has been incorporated in the EL2176/EL2276 to

reduce the variation of output impedance with current output.

This results in dG and dP specifications of 0.15% and 0.15°

while driving 150Ω at a gain of +2.

Video Performance has also been measured with a 500Ω

load at a gain of +1. Under these conditions, the

EL2176/EL2276 have dG and dP specifications of 0.01%

and 0.02° respectively while driving 500 Ω at AV = +1.

Output Drive Capability

In spite of its low 1mA of supply current, the EL2176 is

capable of providing a minimum of ±80mA of output current.

Similarly, each amplifier of the EL2276 is capable of

providing a minimum of ±50mA. These output drive levels

are unprecedented in amplifiers running at these supply

currents. With a minimum ±80mA of output drive, the

EL2176 is capable of driving 50Ω loads to ±4V, making it an

excellent choice for driving isolation transforme rs in

telecommunications applications. Similarly, the ±50mA

minimum output drive of each EL2276 amplifier allows

swings of ±2.5V into 50Ω loads.

Driving Cables and Capacit ive Loads

When used as a cable driver, double termination is always

recommended for reflection-free perf ormance. For those

applications, the back-termination series resistor will

decouple the EL2176/EL2276 from the cable and allow

extensive capacitive drive. However, other applications may

have high capacitive loads without a back-termination

resistor . In these applications, a small series resistor (usually

between 5Ω and 50Ω) can be placed in series with the

output to eliminate most peaking. The gain resistor (RG) can

then be chosen to make up for any gain loss which may be

created by this additional resistor at the output. In many

cases it is also possible to simply increase the value of the

feedback resistor (RF) to reduce the peaking.

Current Limiting

The EL2176/EL2276 have no internal current-limiting

circuitr y. If any output is shorted, it is possible to exceed the

Absolute Maximum Ratings for output current or power

dissipation, potenti ally resulting in the destruction of the

device.

Power Dissipation

With the high output drive capability of the EL2176/EL2276,

it is possible to exceed the 150°C Absolute Maximum

junction temperature under certain very high load current

conditions. Generally speaking, when RL falls below about

25Ω, it is important to calculate the maximum junction

temperatu re (TJmax) for the application to determine if

power-supply voltages, load conditions, or package type

need to be modified for the EL2176/EL2276 to remain in the

EL2176, EL2276

safe operating area. These parameters are calculated as

follows:

TJMAX = TMAX + (θJA * n * PDMAX) [1]

where:

TMAX=Maximum Ambient Temperature

θJA =Thermal Resistance of the Package

n=Number of Amplifiers in the Package

PDMAX=Maximum Power Dissipation of each Amplifier in

the Package

PDMAX for each amplifier can be calculated as follows:

PDMAX = (2 * VS * ISMAX) + (VS - VOUTMAX) *

(VOUTMAX/RL)) [2]

where:

VS=Supply Voltage

ISMAX=Maximum Supply Current of 1 Amplifier

VOUTMAX=Max. Output Voltage of the Application

RL=Load Resistance

Typical Application Circuits

LOW POWER MULTIPLEXER WITH SINGLE-ENDED TTL INPUT

EL2176, EL2276

Typical Application Circuits (Continued)

INVERTING 200mA OUTPUT CURRENT DISTRIBUTION

AMPLIFIER FAST-SETTLING PRECISION AMPLIFIER

DIFFERENTIAL LINE-DRIVER/RECEIVER

EL2176, EL2276

EL2176/EL2276 Macromodel

* Revision A, March 1995

* AC characteristics used Rf=Rg=1KΩ,RL=150Ω

* Connections: +input

* | -input

* | | +Vsupply

* | | | -Vsupply

* | | | | output

* | | | | |

.subckt EL2176/el 3 2 7 4 6

* Input Stage

e1 10 0 3 0 1.0

vis 10 9 0V

h2 9 12 vxx 1.0

r1 2 11 165

l1 11 12 25nH

iinp 3 0 0.5uA

iinm 2 0 4uA

r12 3 0 4Meg

* Slew Rate Limiting

h1 13 0 vis 600

r2 13 14 1K

d1 14 0 dclamp

d2 0 14 dclamp

* High Frequency Pole

e2 30 0 14 0 0.00166666666

l3 30 17 0.5uH

c5 17 0 0.69pF

r5 17 0 300

* Transimpedan ce Stage

g1 0 18 17 0 1.0

rol 18 0 400K

cdp 18 0 1.9pF

* Output Stage

q1 4 18 19 qp

q2 7 18 20 qn

q3 7 19 21 qn

q4 4 20 22 qp

r7 21 6 4

r8 22 6 4

ios1 7 19 0.4mA

ios2 20 4 0.4mA

* Supply Current

ips 7 4 1nA

* Error Terms

ivos 0 23 2mA

EL2176, EL2276

vxx 23 0 0V

e4 24 0 3 0 1.0

e5 25 0 7 0 1.0

e6 26 0 4 0 -1.0

r9 24 23 0.316K

r10 25 23 3.2K

r11 26 23 3.2K

* Models

.model qn npn(is=5e-15 bf=200 tf=0.01nS)

.model qp pnp(is=5e-15 bf=200 tf=0.01nS)

.model dclamp d(is=1e- 30 ibv=0.266

+ bv=1.3v n=4)

.ends

EL2176/EL2276 Macromodel (Continued)

EL2176, EL2276

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