EL2140C2141C
October
1995
Rev
A
EL2140C 2141C
150 MHz Differential Twisted Pair Driver
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
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 or
a
6V 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
Ordering Information
Part No
Temp Range
Package
Outline
EL2140CN
b
40 C to
a
85 C 8-pin PDIP MDP0031
EL2140CS
b
40 C to
a
85 C 8-pin SOIC
MDP0027
EL2141CN
b
40 C to
a
85 C 8-pin PDIP MDP0031
EL2141CS
b
40 C to
a
85 C 8-pin SOIC
MDP0027
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 applica-
tion 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
REF
) which has a
b
3 dB bandwidth of over 100 MHz Gen-
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 de-
pend upon input and output signal amplitude as well as the
output load impedance (See distortion data inside )
Both outputs (V
OUT
V
OUTB
) are short circuit protected to
withstand temporary overload condition
Connection Diagrams
EL2140C
EL2141C
2140-1
2140-2
EL2140C 2141C
150 MHz Differential Twisted Pair Driver
Absolute Maximum Ratings
Supply Voltage (V
CC
V
EE
)
0V 12 6V
Maximum Output Current
g
60 mA
Storage Temperature Range
b
65 C to
a
150 C
Operating Junction Temperaure
a
150 C
Recommended Operating Temperature
b
40 C to 85 C
V
IN
V
INB
V
REF
V
EE
a
0 8V (MIN) to V
CC
b
0 8V (MAX)
V
IN
V
INB
g
5V
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
J
e
T
C
e
T
A
Test Level
Test Procedure
I
100% production tested and QA sample tested per QA test plan QCX0002
II
100% production tested at T
A
e
25 C and QA sample tested at T
A
e
25 C
T
MAX
and T
MIN
per QA test plan QCX0002
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
A
e
25 C for information purposes only
DC Electrical Characteristics
V
CC
e a
5V V
EE
e b
5V T
A
e
25 C V
IN
e
0V R
L
e
200 unless otherwise specified
Parameter
Description
Min
Typ
Max
Test
Units
Level
V
supply
Supply Operating Range (V
CC
V
EE
)
g
3 0
g
5 0
g
6 3
I
V
I
S
Power Supply Current (No Load)
11
14
I
mA
V
OS
Input Referred Offset Voltage
b
25
10
40
I
mV
I
IN
Input Bias Current (V
IN
V
INB
V
REF
)
b
20
6
20
I
mA
Z
IN
Differential Input Impedance
400
V
k
X
V
DIFF
Differential Input Range
g
2 0
g
2 3
I
V
A
V
Voltage Gain (EL2140C) V
IN
e
2V
pk-pk
1 95
1 985
2 02
I
V V
A
VOL
Open Loop Voltage Gain (EL2141C)
75
V
dB
V
CM
Input Common Mode Voltage Range (EL2140C)
b
2 6
a
4 0
I
V
V
OUT
(200)
Output Voltage Swing (200
X load V
OUT
to V
OUTB
) (EL2141C)
g
3 4
g
3 6
I
V
V
OUT
(100)
Output Voltage Swing (100
X Load V
OUT
to V
OUTB
) (EL2141C)
g
2 9
g
3 1
I
V
V
N
Input Referred Voltage Noise
36
V
nV
S
Hz
V
REF
Output Voltage Control Range (EL2140C)
b
2 5
a
3 3
I
V
V
REFOS
Output Offset Relative to V
REF
b
60
b
25
a
60
I
mV
PSRR
Power Supply Rejection Ratio
60
70
I
dB
I
OUT
(min)
Minimum Output Current
50
60
I
mA
CMRR
Input Common Mode Rejection Ratio (EL2140C) V
CM
e
g
2V
60
70
I
dB
R
OUT
(V
OUT
e
V
OUTB
e
0V) Output Impedence
0 1
V
X
2
TD
is
03in
TD
is
37in
EL2140C 2141C
150 MHz Differential Twisted Pair Driver
AC Electrical Characteristics
V
CC
e a
5V V
EE
e b
5V T
A
e
25 C V
IN
e
0V R
LOAD
e
200 unless otherwise specified
Parameter
Description
Min
Typ
Max
Test
Units
Level
BW(
b
3 dB)
b
3 dB Bandwidth (EL2140C and EL2141C
gain of 2)
150
V
MHz
SR
Differential Slewrate
800
V
V
ms
Tstl
Settling Time to 1%
15
V
ns
GBW
Gain Bandwidth Product
400
V
MHz
V
REFBW
(
b
3 dB)
V
REF
b
3 dB Bandwidth
130
V
MHz
V
REFSR
V
REF
Slewrate
100
V
V
ms
THDf1
Distortion at 100 kHz (Note 1)
b
75
V
dB
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
OUT
V
OUTB
e
12V pk-pk R
LOAD
e
200
X Vgain
e
8
Pin Description
Pin No
Pin Name
Function
EL2140C
EL2141C
1
2
V
IN
Non-inverting Input
3
V
INB
Inverting Input (EL2140C only)
1
FBP
Non-inverting Feedback Input Resistor R1 must be Connected from this Pin to V
OUT
(EL2141C only)
4
FBN
Inverting Feedback Input Resistor R3 must be Connected from this pin to V
OUTB
(EL2141C only)
4
3
V
REF
Output Common-mode Control The Common-mode Voltage of V
OUT
and V
OUTB
will
Follow the Voltage on this Pin Note that on the EL2141 this pin is also the V
INB
pin
5
5
V
OUTB
Inverting Output
6
6
V
CC
Positive Supply
7
7
V
EE
Negative Supply
8
8
V
OUT
Non-inverting Output
3
TD
is
20in
EL2140C 2141C
150 MHz Differential Twisted Pair Driver
Typical Performance Curves
I
S
vs Supply Voltage
2140-3
EL2140 Frequency Response
2140-4
Resistor R2 (GAIN e 2)
EL2141 Frequency Response vs
2140-5
vs Temperature
Frequency Response
2140-6
Resistor R2 (GAIN e 8)
EL2141 Frequency Response vs
2140-7
V
IN
e
2V pk pk
(GAIN e 6 R
LOAD
e
200X)
EL2141 Distortion vs Frequency
2140-8
4
EL2140C 2141C
150 MHz Differential Twisted Pair Driver
Typical Performance Curves
Contd
EL2140 CMRR vs Frequency
2140-9
Mode Signal vs Frequency
EL2141 Output Signal and Common
2140-10
EL2140 V
REF
Frequency Response
2140-11
2140-12
EL2140 Small Signal Response (Note 1)
Note 1 Photo shows voltages on a 100
X transmission line terminated at both ends so voltages at V
OUT
V
OUTB
are twice the
values shown
5
EL2140C 2141C
150 MHz Differential Twisted Pair Driver
Applications Information
EL2141C
2140-13
GAIN
e
R1
a
R2
a
R3
R2
EL2140C
2140-14
GAIN e 2
V
OUT
a
V
OUTB
2
e
V
REF
(common mode)
Choice of feedback resistor
There is little to be gained from choosing resistor
R2 values below 400
X and in fact it would only
result in increased power dissipation and signal
distortion Above 400
X 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 k
X
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 distor-
tion for further suggestions)
Capacitance considerations
As with many high bandwidth amplifiers the
EL2140C 2141C prefer not to drive highly capac-
itive loads It is best if the capacitance on V
OUT
and V
OUTB
is kept below 10 pF if the user does
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
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 poten-
tially produce are the 2nd 3rd 5th and 6th
Their amplitude is application dependent
All
other harmonics should be negligible by compari-
son Each should be considered separately
H2 The second harmonic arises from the input
stage and the lower the applied differential sig-
nal 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 Refer-
ring 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
IN
node respectively This would the-
oretically require that R1
a
R2
e
R3 although
the lowest distortion is found at about R3
e
R1
a
(0 7 R2) With this arrangement the second
harmonic should be suppressed well below the
value of the third harmonic
6
EL2140C 2141C
150 MHz Differential Twisted Pair Driver
Applications Information
Contd
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 dis-
tortion 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
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 re-
ducing the third harmonic
H6 The sixth harmonic should not be a problem
and is the result of poor power supply decou-
pling While 100 nF chip capacitors may be suffi-
cient for some applications it would be insuffi-
cient 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
Typical Applications Circuits
2140-15
Figure 1 Typical Twisted Pair Application
7
EL2140C 2141C
150 MHz Differential Twisted Pair Driver
Typical Applications Circuits
Contd
2140-16
Figure 2 Dual Coaxial Cable Driver
2140-17
Figure 3 Single Supply Twisted Pair Driver
8
EL2140C 2141C
150 MHz Differential Twisted Pair Driver
Typical Applications Circuits
Contd
2140-18
Figure 4 Differential Line Driver with Equalization
DC Gain
e
R1
a
R2
a
R3
R2
(See Figure 5)
HF Gain
e
R1
a
(R2
R4)
a
R3
(R2
R4)
(See Figure 5)
2140-19
Figure 5
where f
o
e
1
2
q
C
1
R
2
and f
p
e
1
2
q
C
1
R
4
9
EL2140C 2141C
150 MHz Differential Twisted Pair Driver
Typical Applications Circuits
Contd
2140-20
Figure 6 Dual Signal Transmission Circuit
10
BLANK
11
EL2140C2141C
October
1995
Rev
A
EL2140C 2141C
150 MHz Differential Twisted Pair Driver
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
Elantec Inc
1996 Tarob Court
Milpitas CA 95035
Telephone (408) 945-1323
(800) 333-6314
Fax (408) 945-9305
European Office 44-71-482-4596
WARNING
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-
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
death Users contemplating application of Elantec Inc products
in Life Support Systems are requested to contact Elantec Inc
factory headquarters to establish suitable terms
conditions for
these applications Elantec Inc 's warranty is limited to replace-
ment of defective components and does not cover injury to per-
sons or property or other consequential damages
Printed in U S A
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