Datasheet EL2141CS, EL2141CN, EL2140CS, EL2140CN Datasheet (ELANT)

EL2140C/2141C

150 MHz Differential Twisted Pair Driver

EL2140C/2141C October 1995, Rev A

Features

# Fully differential inputs, outputs,

and feedback

# Differential input range

g

2.3V

# 150 MHz 3 dB bandwidth
# 800 V/ms slew rate

b

#

55 dB distortion at 3 MHz

b

#

75 dB distortion at 100 kHz

g

#

5V supplies ora6V single

supply

# 50 mA minimum output current
# Output swing (200X load) to

within 1.5V of supplies
(14V pk-pk differential)

# Low power-11 mA typical supply

current

Applications

# Twisted pair driver
# Differential line driver
# VGA over twisted pair
# ADSL/HDSL driver
# Single ended to differential

amplification

# Transmission of analog signals in

a noisy environment

General Description

The EL2140C/2141C is a very high bandwidth amplifier whose
output is in differential form, and is thus primarily targeted for
applications such as driving twisted pair lines, or any applica­tion where common mode injection is likely to occur. The input
signal can be in either single-ended or differential form, but the
output is always in differential form.

On the EL2141C, two feedback inputs provide the user with the
ability to set the device gain, (stable at minimum gain of two),
whereas the EL2140C comes with a fixed gain of two.

The output common mode level is set by the reference pin
(V

), which has ab3 dB bandwidth of over 100 MHz. Gen-

REF

erally, this pin is grounded, but it can be tied to any voltage
reference.

The transmission of ADSL/HDSL signals requires very low
distortion amplification, so this amplifier was designed with
this as a primary goal. The actual signal distortion levels de­pend upon input and output signal amplitude, as well as the
output load impedance. (See distortion data inside.)

Both outputs (V

OUT,VOUTB

) are short circuit protected to

withstand temporary overload condition.

Connection Diagrams

EL2140C EL2141C

Ordering Information

Part No. Temp. Range Package Outline

EL2140CNb40§Ctoa85§C 8-pin PDIP MDP0031

EL2140CSb40§Ctoa85§C 8-pin SOIC MDP0027

EL2141CNb40§Ctoa85§C 8-pin PDIP MDP0031

EL2141CSb40§Ctoa85§C 8-pin SOIC MDP0027

Note: All information contained in this data sheet has been carefully checked and is believed to be accurate as of the date of publication; however, this data sheet cannot be a ‘‘controlled document’’. Current revisions, if any, to these
specifications are maintained at the factory and are available upon your request. We recommend checking the revision level before finalization of your design documentation.

©

1995 Elantec, Inc.

Ý

2140-1 2140-2

EL2140C/2141C

150 MHz Differential Twisted Pair Driver

Absolute Maximum Ratings

e

J

Test

Level

b
b

CC

e

T

C

40§Cto85§C

0.8V (MAX)

g

TA.

Units

5V

Supply Voltage (VCC–VEE) 0V–12.6V
Maximum Output Current
Storage Temperature Range
Operating Junction Temperaure

Important Note:
All parameters having Min/Max specifications are guaranteed. The Test Level column indicates the specific device testing actually
performed during production and Quality inspection. Elantec performs most electrical tests using modern high-speed automatic test
equipment, specifically the LTX77 Series system. Unless otherwise noted, all tests are pulsed tests, therefore T

Test Level Test Procedure

I 100% production tested and QA sample tested per QA test plan QCX0002.

II 100% production tested at T

III QA sample tested per QA test plan QCX0002.
IV Parameter is guaranteed (but not tested) by Design and Characterization Data.

V Parameter is typical value at T

DC Electrical Characteristics

ea

V

CC

5V, V

EE

T

eb

MAX

5V, T

and T

A

per QA test plan QCX0002.

MIN

e

25§C, V

IN

g

b

A

e

60 mA

65§Ctoa150§C

a

150§C

e

25§C and QA sample tested at T

e

25§C for information purposes only.

A

e

0V, R

L

Recommended Operating Temperature
V

IN,VINB,VREF

V

IN–VINB

e

25§C,

A

200, unless otherwise specified

a

V

0.8V (MIN) to V

EE

Parameter Description Min Typ Max

V

supply

I

S

V

OS

I

IN

Z

IN

V

DIFF

A

V

A

VOL

V

CM

V

(200) Output Voltage Swing (200X load, V

OUT

V

(100) Output Voltage Swing (100X Load, V

OUT

V

N

V

REF

V

REFOS

Supply Operating Range (VCC–VEE)

Power Supply Current (No Load) 11 14 I mA

Input Referred Offset Voltage

Input Bias Current (VIN,V

Differential Input Impedance 400 V kX

Differential Input Range

Voltage Gain (EL2140C) V

Open Loop Voltage Gain (EL2141C) 75 V dB

Input Common Mode Voltage Range (EL2140C)

Input Referred Voltage Noise 36 V nV/SHz

Output Voltage Control Range (EL2140C)

Output Offset Relative to V

INB,VREF

e

2V

IN

REF

)

pk-pk

OUT

OUT

to V

to V

) (EL2141C)

OUTB

) (EL2141C)g2.9g3.1 I V

OUTB

g

3.0g5.0g6.3 I V

b

25 10 40 I mV

b

20 6 20 I mA

g

2.0g2.3 I V

1.95 1.985 2.02 I V/V

b

2.6

g

3.4g3.6 I V

b

2.5

b60b

a

4.0 I V

a

3.3 I V

a

25

60 I mV

PSRR Power Supply Rejection Ratio 60 70 I dB

I

(min) Minimum Output Current 50 60 I mA

OUT

e

CMRR Input Common Mode Rejection Ratio (EL2140C) V

R

OUT

e

(V

OUT

V

OUTB

e

0V) Output Impedence 0.1 V X

g

2V 60 70 I dB

CM

TDis0.3inTDis3.7in

2

EL2140C/2141C

150 MHz Differential Twisted Pair Driver

AC Electrical Characteristics

ea

V

CC

Parameter Description Min Typ Max

BW(b3 dB)

SR Differential Slewrate 800 V V/ms

Tstl Settling Time to 1% 15 V ns

GBW Gain Bandwidth Product 400 V MHz

V

REFBW

V

REFSR

THDf1 Distortion at 100 kHz (Note 1)

dP Differential Phase@3.58 MHz 0.16 V

dG Differential Gain@3.58 MHz 0.24 V %

Note 1: Distortion measurement quoted for V

Pin Description

Pin No.

EL2140C EL2141C

12VINNon-inverting Input

3V

43V

55V

66VCCPositive Supply

77VEENegative Supply

88V

eb

5V, V

EE

(b3 dB) V

1 FBP Non-inverting Feedback Input. Resistor R1 must be Connected from this Pin to V

4 FBN Inverting Feedback Input. Resistor R3 must be Connected from this pin to V

e

5V, T

b

REF

V

REF

25§C, V

A

3 dB Bandwidth (EL2140C and EL2141C@gain of 2) 150 V MHz

b

3 dB Bandwidth 130 V MHz

Slewrate 100 V V/ms

Pin Name Function

INB

REF

OUTB

OUT

e

0V, R

IN

OUT–VOUTB

Inverting Input (EL2140C only)

(EL2141C only)

(EL2141C only)

Output Common-mode Control. The Common-mode Voltage of V
Follow the Voltage on this Pin. Note that on the EL2141, this pin is also the V

Inverting Output

Non-inverting Output

LOAD

e

200, unless otherwise specified

e

12V pk-pk, R

LOAD

e

b

75 V dB

200X, Vgaine8.

OUT

Test

Level

and V

OUTB

OUTB

INB

OUT

.

will
pin.

Units

§

TDis2.0in

.

3

EL2140C/2141C

150 MHz Differential Twisted Pair Driver

Typical Performance Curves

ISvs Supply Voltage

EL2141 Frequency Response vs
Resistor R2 (GAINe2)

2140-3

EL2140 Frequency Response

Frequency Response
vs Temperature

2140-4

EL2141 Frequency Response vs
Resistor R2 (GAINe8)

2140-5

2140-7

2140-6

EL2141 Distortion vs Frequency
(GAIN
V

IN

e

e

2V pk/pk

6, R

LOAD

e

200X)

2140-8

4

EL2140C/2141C

150 MHz Differential Twisted Pair Driver

Typical Performance Curves

EL2140 CMRR vs Frequency

Ð Contd.

2140-9

EL2140 V

Frequency Response

REF

EL2141 Output Signal and Common
Mode Signal vs Frequency

2140-10

2140-11

2140-12

EL2140 Small Signal Response (Note 1)

Note 1: Photo shows voltages on a 100X transmission line terminated at both ends, so voltages at V

values shown.

5

OUT,VOUTB

are twice the

EL2140C/2141C

150 MHz Differential Twisted Pair Driver

Applications Information

EL2141C

2140-13

R1aR2aR3

e

GAIN

R2

Choice of feedback resistor

There is little to be gained from choosing resistor
R2 values below 400X and, in fact, it would only
result in increased power dissipation and signal
distortion. Above 400X, the bandwidth response
will develop some peaking (for a gain of two), but
substantially higher resistor R2 values may be
used for higher voltage gains, such as up to 2 kX
at a gain of eight before peaking will develop. R1
and R3 are selected as needed to set the voltage
gain, and while R1

e

R3 is suggested, the gain
equation above holds for any values (see distor­tion for further suggestions).

Capacitance considerations

As with many high bandwidth amplifiers, the
EL2140C/2141C prefer not to drive highly capac­itive loads. It is best if the capacitance on V
and V

is kept below 10 pF if the user does

OUTB

OUT

not want gain peaking to develop.

In addition, on the EL2141C, the two feedback
nodes FBP and FBN should be laid out so as to
minimize stray capacitance, else an additional
pole will potentially develop in the response with
possible gain peaking.

EL2140C

2140-14

V

OUT

GAINe2

a

V

OUTB

2

e

V

REF

(common mode)

The amount of capacitance tolerated on any of
these nodes in an actual application will also be
dependent on the gain setting and the resistor
values in the feedback network.

Distortion considerations

The harmonics that these amplifiers will poten­tially produce are the 2nd, 3rd, 5th, and 6th.
Their amplitude is application dependent. All
other harmonics should be negligible by compari­son. Each should be considered separately:

H2 The second harmonic arises from the input
stage, and the lower the applied differential sig­nal amplitude, the lower the magnitude of the
second harmonic. For practical considerations of
required output signal and input noise levels, the
user will end up choosing a circuit gain. Refer­ring to Figure 1, it is best if the voltage at the
negative feedback node tracks the V

REF

node,
and the voltage at the positive feedback node
tracks the V
oretically require that R1
the lowest distortion is found at about R3

a

(0.7*R2). With this arrangement, the second

node respectively. This would the-

IN

aR2e

R3, although

e

R1

harmonic should be suppressed well below the
value of the third harmonic.

6

EL2140C/2141C

150 MHz Differential Twisted Pair Driver

Applications Information

H3 The third harmonic should be the dominant

harmonic and is primarily affected by output
load current which, of course, is unavoidable.
However, this should encourage the user not to
waste current in the gain setting resistors, and to
use values that consume only a small proportion
of the load current, so long as peaking does not
occur. The more load current, the worse the dis­tortion, but depending on the frequency, it may
be possible to reduce the amplifier gain so that
there is more internal gain left to cancel out any
distortion.

Ð Contd.

Typical Applications Circuits

H5 The fifth harmonic should always be below

the third, and will not become significant until
heavy load currents are drawn. Generally, it
should respond to the same efforts applied to re­ducing the third harmonic.

H6 The sixth harmonic should not be a problem
and is the result of poor power supply decou­pling. While 100 nF chip capacitors may be suffi­cient for some applications, it would be insuffi­cient for driving full signal swings into a twisted
pair line at 100 kHz. Under these conditions, the
addition of 4.7 mF tantalum capacitors would
cure the problem.

Figure 1. Typical Twisted Pair Application

7

2140-15

EL2140C/2141C

150 MHz Differential Twisted Pair Driver

Typical Applications Circuits

Figure 2. Dual Coaxial Cable Driver

Figure 3. Single Supply Twisted Pair Driver

Ð Contd.

2140-16

2140-17

8

EL2140C/2141C

150 MHz Differential Twisted Pair Driver

Typical Applications Circuits

Figure 4. Differential Line Driver with Equalization

R1aR2aR3

DC Gain

HF Gain

e

e

R2

R1a(R2//R4)aR3

(R2//R4)

(See Figure 5)

(See Figure 5)

Ð Contd.

2140-18

where f

and f

p

e

o

e

2 q C1R

1

2 q C1R

1

4

Figure 5

2140-19

2

9

EL2140C/2141C

150 MHz Differential Twisted Pair Driver

Typical Applications Circuits

Figure 6. Dual Signal Transmission Circuit

Ð Contd.

2140-20

10

BLANK

11

EL2140C/2141C

150 MHz Differential Twisted Pair Driver

EL2140C/2141COctober 1995, Rev A

General Disclaimer

Specifications contained in this data sheet are in effect as of the publication date shown. Elantec, Inc. reserves the right to make changes
in the circuitry or specifications contained herein at any time without notice. Elantec, Inc. assumes no responsibility for the use of any
circuits described herein and makes no representations that they are free from patent infringement.

WARNING Ð Life Support Policy

Elantec, Inc. products are not authorized for and should not be
used within Life Support Systems without the specific written
consent of Elantec, Inc. Life Support systems are equipment in-

Elantec, Inc.

1996 Tarob Court
Milpitas, CA 95035
Telephone: [phone]

[phone]

Fax: [phone]

European Office: 44-71-482-4596

tended to support or sustain life and whose failure to perform
when properly used in accordance with instructions provided can
be reasonably expected to result in significant personal injury or
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in Life Support Systems are requested to contact Elantec, Inc.
factory headquarters to establish suitable terms & conditions for
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Printed in U.S.A.12