Elantec EL2140CS 150 mhz differential twisted pair driver Datasheet

150 MHz Differential Twisted Pair Driver
Features
General Description
# 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
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.
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
EL2140C/2141C
EL2140C/2141C
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
(VREF), which has a b 3 dB bandwidth of over 100 MHz. Generally, 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 (VOUT, VOUTB) are short circuit protected to
withstand temporary overload condition.
Connection Diagrams
EL2140C
EL2141C
Ordering Information
Part No.
Temp. Range
Package
Outline Ý
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
2140-1
2140-2
October 1995, Rev A
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.
EL2140C/2141C
Absolute Maximum Ratings
Supply Voltage (VCC – VEE)
Maximum Output Current
Storage Temperature Range
Operating Junction Temperaure
b 40§ C to 85§ C
Recommended Operating Temperature
VIN, VINB, VREF
VEE a 0.8V (MIN) to VCCb0.8V (MAX)
g 5V
VIN –VINB
0V – 12.6V
g 60 mA
b 65§ C to a 150§ C
a 150§ C
TD is 0.3in
150 MHz Differential Twisted Pair Driver
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 TJ e TC e TA.
Test Level
I
II
III
IV
V
Test Procedure
100% production tested and QA sample tested per QA test plan QCX0002.
100% production tested at TA e 25§ C and QA sample tested at TA e 25§ C ,
TMAX and TMIN per QA test plan QCX0002.
QA sample tested per QA test plan QCX0002.
Parameter is guaranteed (but not tested) by Design and Characterization Data.
Parameter is typical value at TA e 25§ C for information purposes only.
DC Electrical Characteristics
VCC e a 5V, VEE e b5V, TA e 25§ C, VIN e 0V, RL e 200, unless otherwise specified
Description
Min
Typ
Max
Test
Level
g 3.0
g 5.0
g 6.3
I
V
11
14
I
mA
10
40
I
mV
6
20
I
mA
V
kX
Vsupply
Supply Operating Range (VCC – VEE)
IS
Power Supply Current (No Load)
VOS
Input Referred Offset Voltage
b 25
IIN
Input Bias Current (VIN, VINB, VREF)
b 20
ZIN
Differential Input Impedance
VDIFF
Differential Input Range
g 2.0
g 2.3
AV
Voltage Gain (EL2140C) VIN e 2V pk-pk
1.95
1.985
AVOL
Open Loop Voltage Gain (EL2141C)
400
2.02
75
a 4.0
Units
I
V
I
V/V
V
dB
VCM
Input Common Mode Voltage Range (EL2140C)
b 2.6
I
V
VOUT(200)
Output Voltage Swing (200X load, VOUT to VOUTB) (EL2141C)
g 3.4
g 3.6
I
V
VOUT(100)
Output Voltage Swing (100X Load, VOUT to VOUTB) (EL2141C)
g 2.9
g 3.1
I
V
VN
Input Referred Voltage Noise
V
nV/ SHz
VREF
Output Voltage Control Range (EL2140C)
b 2.5
VREFOS
Output Offset Relative to VREF
b 60
PSRR
Power Supply Rejection Ratio
60
70
I
dB
IOUT(min)
Minimum Output Current
50
60
I
mA
CMRR
Input Common Mode Rejection Ratio (EL2140C) VCM e g 2V
60
70
I
dB
ROUT
(VOUT e VOUTB e 0V) Output Impedence
0.1
V
X
36
2
b 25
a 3.3
I
V
a 60
I
mV
TD is 3.7in
Parameter
EL2140C/2141C
150 MHz Differential Twisted Pair Driver
AC Electrical Characteristics
Parameter
Description
Min
@
gain of 2)
Test
Level
Units
150
V
MHz
800
V
V/ms
Typ
Max
BW(b3 dB)
b 3 dB Bandwidth (EL2140C and EL2141C
SR
Differential Slewrate
Tstl
Settling Time to 1%
15
V
ns
GBW
Gain Bandwidth Product
400
V
MHz
VREFBW(b3 dB)
VREF b3 dB Bandwidth
130
V
MHz
VREFSR
VREF Slewrate
100
V
V/ms
THDf1
Distortion at 100 kHz (Note 1)
b 75
V
dB
dP
Differential Phase
0.16
V
§
dG
Differential Gain
0.24
V
%
@
@
3.58 MHz
3.58 MHz
Note 1: Distortion measurement quoted for VOUT –VOUTB e 12V pk-pk, RLOAD e 200X, Vgain e 8.
Pin Description
Pin No.
EL2140C EL2141C
1
2
3
Pin Name
Function
VIN
Non-inverting Input
VINB
Inverting Input (EL2140C only)
1
FBP
Non-inverting Feedback Input. Resistor R1 must be Connected from this Pin to VOUT.
(EL2141C only)
4
FBN
Inverting Feedback Input. Resistor R3 must be Connected from this pin to VOUTB.
(EL2141C only)
4
3
VREF
Output Common-mode Control. The Common-mode Voltage of VOUT and VOUTB will
Follow the Voltage on this Pin. Note that on the EL2141, this pin is also the VINB pin.
5
5
VOUTB
Inverting Output
6
6
VCC
Positive Supply
7
7
VEE
Negative Supply
8
8
VOUT
Non-inverting Output
3
TD is 2.0in
VCC e a 5V, VEE e b5V, TA e 25§ C, VIN e 0V, RLOAD e 200, unless otherwise specified
EL2140C/2141C
150 MHz Differential Twisted Pair Driver
Typical Performance Curves
IS vs Supply Voltage
EL2140 Frequency Response
2140-3
2140-4
EL2141 Frequency Response vs
Resistor R2 (GAIN e 2)
Frequency Response
vs Temperature
2140-5
2140-6
EL2141 Distortion vs Frequency
(GAIN e 6, RLOAD e 200X)
VIN e 2V pk/pk
EL2141 Frequency Response vs
Resistor R2 (GAIN e 8)
2140-7
2140-8
4
EL2140C/2141C
150 MHz Differential Twisted Pair Driver
Typical Performance Curves Ð Contd.
EL2141 Output Signal and Common
Mode Signal vs Frequency
EL2140 CMRR vs Frequency
2140-9
2140-10
EL2140 VREF Frequency Response
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 VOUT, VOUTB are twice the
values shown.
5
EL2140C/2141C
150 MHz Differential Twisted Pair Driver
Applications Information
EL2141C
EL2140C
2140-14
GAIN e 2
VOUT a VOUTB
e VREF
2
(common mode)
2140-13
GAIN e
R1 a R2 a R3
R2
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.
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).
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 VREF node,
and the voltage at the positive feedback node
tracks the VIN node respectively. This would theoretically 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.
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 VOUT
and VOUTB 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.
6
EL2140C/2141C
150 MHz Differential Twisted Pair Driver
Applications Information Ð Contd.
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.
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.
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.
Typical Applications Circuits
2140-15
Figure 1. Typical Twisted Pair Application
7
EL2140C/2141C
150 MHz Differential Twisted Pair Driver
Typical Applications Circuits Ð 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 Ð Contd.
2140-18
Figure 4. Differential Line Driver with Equalization
DC Gain e
R1 a R2 a R3
(See Figure 5)
R2
HF Gain e
R1 a (R2//R4) a R3
(See Figure 5)
(R2//R4)
2140-19
Figure 5
where fo e
and fp e
1
2 q C 1 R2
1
2 q C 1 R4
9
EL2140C/2141C
150 MHz Differential Twisted Pair Driver
Typical Applications Circuits Ð Contd.
2140-20
Figure 6. Dual Signal Transmission Circuit
10
11
BLANK
EL2140C/2141C
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.
October 1995, Rev A
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Elantec, Inc. products are not authorized for and should not be
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consent of Elantec, Inc. Life Support systems are equipment intended 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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1996 Tarob Court
Milpitas, CA 95035
Telephone: (408) 945-1323
(800) 333-6314
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12
Printed in U.S.A.
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