MAXIM MAX4142ESD

19-4763; Rev 0; 7/98
KIT
ATION
EVALU
E
L
B
A
AVAIL
250MHz, Low-Power,
High-Output-Current, Differential Line Driver
____________________________Features
♦ 250MHz -3dB Bandwidth (AV = +2V/V)
♦ 1400V/µs Slew Rate
♦ 67dB at 10MHz CMR
♦ 0.01%/0.01° Differential Gain/Phase
♦ ±6V Differentially into 100Ω Output Drive
♦ 1mA Shutdown Capability
♦ 12.5mA Quiescent Supply Current
♦ Available in 14-Pin Narrow SO Package
Ordering Information
PART
MAX4142ESD
TEMP. RANGE
-40°C to +85°C
PIN-PACKAGE
14 SO
Pin Configuration
TOP VIEW
VEE 1
14 VCC
IN+ 2
________________________Applications
MAX4142
N.C. 3
Video Twisted-Pair Driver
12 SENSE+
11 GND
SHDN 4
Differential Pulse Amplifier
13 OUT+
10 SENSE-
N.C. 5
High-Speed Instrumentation Amplifier
IN- 6
9
OUT-
Low-Noise Differential Receivers
VEE 7
8
VCC
Differential ADC Driver
SO
N.C. = NOT INTERNALLY CONNECTED
Typical Application Circuit
IN+
Rt
Rt
SENSE+
SENSE
IN75Ω
OUT+
MAX4142
GND
OUT-
IN+
MAX4144
IN-
75Ω
COAX
VOUT
OUT
75Ω
SENSE-
Rt
Rt
REF
TWISTED-PAIR TO COAX-CABLE CONVERTER
________________________________________________________________ Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 408-737-7600 ext. 3468.
MAX4142
General Description
The MAX4142 differential line driver combines highspeed performance with fully symmetrical differential
inputs and outputs. With an internally set +2V/V closedloop gain, the MAX4142 is ideal for driving backterminated cables and transmission lines.
This device utilizes laser-trimmed thin-film resistors and
common-mode cancellation circuitry to deliver an outstanding 67dB at 10MHz common-mode rejection
(CMR). Using current-feedback techniques, the
MAX4142 achieves a 250MHz -3dB (AV = +2V/V) bandwidth, a 70MHz 0.1dB bandwidth, and a 1400V/µs slew
rate. Excellent differential gain/phase error and noise
specifications make this amplifier an excellent choice
for a wide variety of video and RF signal-processing
applications.
The MAX4142 operates from ±5V power supplies and
requires only 12.5mA of quiescent current. The output
stage is capable of driving a 100Ω load to ±6V (differentially) or to ±3V (single-ended). The MAX4142 is
available in a space-saving 14-pin SO package. For a
pin-compatible, higher speed differential line driver,
see the MAX4147 data sheet.
MAX4142
250MHz, Low-Power, High-Output-Current,
Differential Line Driver
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (VCC to VEE)................................................+12V
Voltage on Any Pin to Ground..........(VEE - 0.3V) to (VCC + 0.3V)
Input Current (IN_)............................................................±10mA
Short-Circuit Duration (VOUT to GND) ................................10sec
Continuous Power Dissipation (TA = +70°C)
Plastic SO (derate 8.3mW/°C above +70°C) ................667mW
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10sec) .............................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
DC ELECTRICAL CHARACTERISTICS
(VCC = +5V, VEE = -5V, SHDN = 0, RL = ∞, TA = TMIN to TMAX, unless otherwise noted. Typical values specified at TA = +25°C.)
PARAMETER
SYMBOL
Operating Supply Voltage
Input Offset Voltage
CONDITIONS
Guaranteed by PSR test
MIN
TYP
±4.5
UNITS
±5.5
V
8
mV
VOS
VIN = 0
TCVOS
VIN = 0
3
IB
VIN = 0
10
25
µA
Input Offset Current
IOS
VIN = 0
0.2
2.5
µA
Input Capacitance
CIN
1
pF
Differential Input Resistance
RIN
1
MΩ
Input Offset Voltage Drift
Input Bias Current
Differential Input Voltage Range
Common-Mode Input Voltage Range
Gain
VCM
AV
Gain Error
Gain Drift
0.4
MAX
Guaranteed by output voltage swing test
-3.0
Guaranteed by CMR test
-1.7
3.0
1.7
-1V ≤ VOUT ≤ 1V, RL = 53Ω
2
-1V ≤ VOUT ≤ 1V, RL = 53Ω
0.3
RL = 53Ω
µV/°C
V
V
V/V
2
%
20
ppm/°C
Common-Mode Rejection
CMR
VCM = ±1.7V
55
80
dB
Power-Supply Rejection
PSR
VS = ±4.5V to ±5.5V
65
95
Quiescent Supply Current
ICC, IEE
Shutdown Supply Current
ICC, SHDN
Output Voltage Swing
 VOUT
Output Current Drive
IOUT
Output Resistance
ROUT
SHDN Logic-High Threshold
VIH
SHDN Logic-Low Threshold
VIL
VIN = 0
VSHDN ≥ 2V, VIN = 0
18
mA
1.0
2.0
mA
Single-ended, RL = ∞
3.0
3.4
Differential, RL = ∞
6.0
6.8
Single-ended, RL = 26.5Ω
2.0
2.4
Differential, RL = 53Ω
4.0
4.8
RL = 20Ω
120
75
Ω
0.8
tON
500
3.5
VSHDN = 0
V
V
tOFF
2
mA
2.0
Disable Time to Shutdown
ISHDN
V
0.1
Enable Time from Shutdown
SHDN Input Current
dB
12.5
66
_______________________________________________________________________________________
ns
µs
150
µA
250MHz, Low-Power, High-Output-Current,
Differential Line Driver
(VCC = +5V,
VEE = -5V, SHDN =
0V, RL = 150Ω differential, CONDITIONS
TA = TMIN to TMAX, unless otherwiseMIN
noted. Typical
PARAMETER
SYMBOL
TYP values
MAX specified
UNITSat
T-3dB
A = +25°C.)
Bandwidth
BW(-3dB) VOUT ≤ 0.1VRMS
250
MHz
Full-Power Bandwidth
FPBW
VOUT = 2Vp-p
180
MHz
0.1dB Bandwidth
BW(0.1dB)
Common-Mode Rejection
CMR
Slew Rate
70
MHz
f = 10MHz, VCM = ±2V
67
dB
1400
V/µs
Differential, -2V ≤ VOUT ≤ +2V
SR
Settling Time
VOUT ≤ 0.1VRMS
-1V ≤ VOUT ≤ +1V
tS
to 0.1%
25
to 0.01%
45
ns
Differential Gain
DG
f = 3.58MHz
0.01
%
Differential Phase
DP
f = 3.58MHz
Input Voltage Noise
en
Input Current Noise
in
Spurious-Free Dynamic
Range
SFDR
0.01
degrees
f = 10kHz
8
nV/√Hz
f = 1MHz to 100MHz
80
µVRMS
f = 10kHz
2
pA√Hz
f = 1MHz to 100MHz
20
nARMS
fC = 500kHz, VOUT = 1Vp-p, RS = 50Ω, Figure1
-84
fC = 10MHz, VOUT = 1Vp-p, RS = 50Ω, Figure1
-76
dBc
__________________________________________Typical Operating Characteristics
(VCC = +5V, VEE = -5V, SHDN = 0, RL = 150Ω differential, TA = +25°C, unless otherwise noted.)
8
6.1
7
6
6.0
6
4
GAIN (dB)
6.2
7
5
5.9
5.8
5
4
3
5.7
3
2
5.6
2
1
5.5
1
0
5.4
0.1
1
10
FREQUENCY (MHz)
100
1000
VOUT = 2Vp-p
9
8
GAIN (dB)
GAIN (dB)
VOUT = 100mVp-p
6.3
10
MAX4142-02
VOUT = 100mVp-p
9
6.4
MAX4142-01
10
LARGE-SIGNAL GAIN
vs. FREQUENCY
GAIN FLATNESS vs. FREQUENCY
MAX4142-03
SMALL-SIGNAL GAIN
vs. FREQUENCY
0
0.1
1
10
FREQUENCY (MHz)
100
1000
0.1
1
10
100
1000
FREQUENCY (MHz)
_______________________________________________________________________________________
3
MAX4142
AC ELECTRICAL CHARACTERISTICS
_____________________________Typical Operating Characteristics (continued)
(VCC = +5V, VEE = -5V, SHDN = 0, RL = 150Ω differential, TA = +25°C, unless otherwise noted.)
COMMON-MODE REJECTION
vs. FREQUENCY
20
50
30
CMR (dB)
10
40
60
70
40
50
80
60
90
70
100
80
0.1
1
10
10
1
0.01
0.1
100
100
0.1
90
110
1
10
100
1000
0.1
1
10
100
FREQUENCY (MHz)
FREQUENCY (MHz)
FREQUENCY (MHz)
VOLTAGE-NOISE DENSITY
vs. FREQUENCY
CURRENT-NOISE DENSITY
vs. FREQUENCY
HARMONIC DISTORTION
vs. FREQUENCY
MAX4142-09
MAX4142-08
0
RL = 150Ω
VOUT = 1Vp-p
-10
-20
DISTORTION (dBc)
10
100
CURRENT-NOISE DENSITY (pA/√Hz)
MAX4142-07
100
VOLTAGE-NOISE DENSITY (nV/√Hz)
MAX4142-05
0
30
OUTPUT IMPEDANCE vs. FREQUENCY
1000
OUTPUT IMPEDANCE (Ω)
20
PSR (dB)
-10
MAX4142-04
10
MAX4142-06
POWER-SUPPLY REJECTION
vs. FREQUENCY
10
-30
2nd
HARMONIC
-40
-50
-60
-70
3rd
HARMONIC
-80
1k
10k
100k
10
100
1k
10k
100k
FREQUENCY (Hz)
FREQUENCY (Hz)
DISTORTION vs. LOAD
HARMONIC DISTORTION
vs. OUTPUT VOLTAGE SWING
-40
-70
2nd ORDER
HARMONIC
-80
3rd ORDER
HARMONIC
-50
-100
-100
0
200
400
600
800
RESISTIVE LOAD (Ω)
1000
1200
0.010
0.005
0.000
0
2nd
HARMONIC
-80
-90
100
-0.005
-70
-90
0.015
3rd
HARMONIC
-60
DIFF. PHASE (deg)
DISTORTION (dBc)
-60
10
DIFFERENTIAL GAIN AND PHASE
-40
-50
1
FREQUENCY (MHz)
f = 5MHz
RL = 150Ω
-30
0.1
1M
MAX4142-11
-20
MAX4142-10
fO = 5MHz,
VOUT = 1Vp-p
-30
1M
DIFF. GAIN (%)
100
-20
4
-90
1
10
MAX4142-12
1
DISTORTION (dBc)
MAX4142
250MHz, Low-Power, High-Output-Current,
Differential Line Driver
100
0.010
0.005
0.000
-0.005
0
2
4
6
8
10
12
0
OUTPUT VOLTAGE SWING (Vp-p)
_______________________________________________________________________________________
100
IRE
250MHz, Low-Power, High-Output-Current,
Differential Line Driver
(VCC = +5V, VEE = -5V, SHDN = 0, RL = 150Ω differential, TA = +25°C, unless otherwise noted.)
DIFFERENTIAL OUTPUT VOLTAGE
SWING vs. TEMPERATURE
12
10
8
6
4
2
17
16
15
14
13
12
100
200
300
400
0.7
0.6
0.5
0.4
0.3
0.2
0
-45 -30 -15
500
0
15
30
45
60
75
-45 -30 -15
90
0
15
30
45
60
LOAD RESISTANCE (Ω)
TEMPERATURE (°C)
TEMPERATURE (°C)
INPUT BIAS CURRENT
vs. TEMPERATURE
INPUT OFFSET CURRENT
vs. TEMPERATURE
POWER-SUPPLY CURRENT
vs. TEMPERATURE
17
15
13
11
9
0.7
0.6
0.5
0.4
0.3
0.2
7
0.1
5
0
-45 -30 -15
0
15
30
45
60
75
SMALL-SIGNAL PULSE RESPONSE
90
14.0
13.5
13.0
12.5
12.0
11.5
11.0
10.0
0
15
30
45
60
75
90
-45 -30 -15
TEMPERATURE (°C)
TEMPERATURE (°C)
75
14.5
10.5
-45 -30 -15
90
90
MAX4142-18
0.8
75
15.0
POWER-SUPPLY CURRENT (mA)
0.9
INPUT OFFSET CURRENT (µA)
19
MAX4142-17
1.0
MAX4142-16
0
0.8
0.1
0
0
15
30
45
60
TEMPERATURE (°C)
LARGE-SIGNAL PULSE RESPONSE
MAX4142-19
ENABLE RESPONSE TIME
MAX4142-20
MAX4142-21
5V
GND
VOLTAGE (500mV/div)
IN
VOLTAGE (25mV/div)
INPUT BIAS CURRENT (µA)
0.9
INPUT OFFSET VOLTAGE (mV))
14
OUTPUT SWING (Vp-p)
RL = 1MΩ DIFFERENTIAL
DIFFERENTIAL OUTPUT VOLTAGE SWING (V)
16
1
MAX4142-14
18
MAX4142-13
18
INPUT OFFSET VOLTAGE
vs. TEMPERATURE
MAX4142-15
DIFFERENTIAL OUTPUT SWING
vs. LOAD RESISTANCE
GND
OUT
GND
IN
SHDN
0V
2V
GND
OUT
VOUT
0V
TIME (10ns/div)
TIME (10ns/div)
TIME (2µs/div)
_______________________________________________________________________________________
5
MAX4142
_____________________________Typical Operating Characteristics (continued)
MAX4142
250MHz, Low-Power, High-Output-Current,
Differential Line Driver
_____________________Pin Description
PIN
NAME
FUNCTION
1, 7
VEE
Negative Power Supply. Connect VEE
to -5V.
2
IN+
Noninverting Input
3, 5
N.C.
No Connect. Not internally connected.
4
SHDN
Logic Input for Shutdown Circuitry. A
logic low enables the amplifier. A logic
high disables the amplifier.
6
IN-
Inverting Input
8, 14
VCC
Positive Power Supply. Connect VCC
to +5V.
9
OUT-
Inverting Output
10
SENSE-
11
GND
12
SENSE+
13
OUT+
IN+
RF
Ground
OUT+
SENSE+
RG
VIN
A3
GND
( )
R
VOUT = 1 + F VIN
RG
RG
SENSERF
Inverting Output Sense. Connect to OUTclose to the pin for normal operation.
A2
OUT-
IN-
Noninverting Output Sense. Connect
to OUT+ close to the pin for normal
operation.
Noninverting Output
Detailed Description
The MAX4142 differential line driver features 250MHz
bandwidth and 67dB common-mode rejection (CMR) at
10MHz. This part achieves a 1400V/µs slew rate, and
power dissipation is only 125mW. The MAX4142 has an
internally set +2V/V closed-loop gain, making it ideal as
a back-terminated line driver. The output stage can
drive ±6V into a 100Ω load.
The MAX4142 utilizes a three-amplifier topology to provide differential inputs/outputs and common-mode
feedback (Figure 1), making it ideal for applications
with high common-mode noise, such as for driving T1
or xDSL transmissions over a twisted-pair cable. The
MAX4142’s differential noninverting structure uses two
noninverting amplifiers (A1 and A2) to provide a single
device with differential inputs and outputs. The use of
two amplifiers effectively doubles the output voltage
swing and bandwidth, and improves slew rate when
compared to the single op-amp differential amplifier.
Excellent gain and phase, along with low noise, also
make the MAX4142 suitable for video applications and
RF-signal processing.
For a complete differential transmission link, use the
MAX4142 line driver with the MAX4144/MAX4146 line
receivers, as shown in the Typical Application Circuit.
6
MAX4142
A1
Figure 1. MAX4142 Functional Diagram
Applications Information
Balanced Transmission Lines
Differential (balanced) transmission lines use two conductors to transmit high-speed signals over low-cost
cable or twisted-pair wire with minimal signal degradation. The transmit side of the balanced transmission line
is driven by an amplifier with differential outputs, while
the signal is received by an amplifier with differential
inputs. In an ideal balanced system, each conductor
has the same impedance from input to output and from
the conductor to the system ground. Since the impedance from each conductor to ground is equivalent, any
noise or other interference coupled into the transmission line will be equal in magnitude in each conductor,
appearing as a common-mode signal to the amplifier at
the receiving end of the transmission line. Since the
receiving amplifier subtracts the signals on each side
of the transmission line to obtain the desired information, common-mode signals are effectively canceled
out by the receiving amplifier.
Common-Mode Feedback
In nonideal balanced systems, impedance mismatches
between the conductors of a transmission line can
degrade system common-mode rejection (CMR) by
converting a portion of any common-mode signal to a
_______________________________________________________________________________________
250MHz, Low-Power, High-Output-Current,
Differential Line Driver
IN+
MAX4142
A1
RF
RF
• High-frequency design techniques must be followed
when designing the PC board for the MAX4142.
• Use surface-mount power-supply bypass capacitors
instead of through-hole capacitors. Their shorter lead
lengths reduce parasitic inductance, leading to
superior high-frequency performance.
• Keep signal lines as short and as straight as possible. Do not make 90° turns; round all corners.
• The ground plane should be as free from voids as
possible.
A differential input voltage as high as 10V will cause
only 2.1mA to flow—much less than the 10mA absolute
maximum rating.
OUT-
A2
IN-
Figure 2. MAX4142 Input Protection Circuit
IN-
MAX4142
OUT700Ω
Input Stage Circuitry
The MAX4142 includes internal protection circuitry that
prevents damage to the precision input stage from
large differential input voltages. This protection circuitry
consists of five back-to-back Schottky protection
diodes between IN+ and R G, and IN- and RG (Figure 2). The diodes limit the differential voltage applied
to the amplifiers’ internal circuitry to no more than 10VF,
where VF is the diode’s forward voltage drop (about
0.4V at +25°C).
For a large differential input voltage (exceeding 4V), the
MAX4142 input bias current (at IN+ and IN-) increases
according to the following equation:
Input current = [(VIN+ - VIN-) - 10VF] / 1.4kΩ
SENSE+
SENSE-
Observe the following guidelines when designing your
PC board:
• Do not use wire-wrap boards; they are too inductive.
• Do not use IC sockets; they increase parasitic
capacitance and inductance.
OUT+
2RG
Grounding, Bypassing,
and PC Board Layout
• The printed circuit board should have at least two
layers: the signal layer and the ground plane.
MAX4142
differential signal that is amplified by the receiver. The
unique topology of the MAX4142 (Figure 1) utilizes two
amplifiers (A1 and A2) to provide differential inputs and
outputs, and a third amplifier (A3) to provide commonmode feedback. The common-mode feedback amplifier senses common-mode voltage at the MAX4142
output and forces this voltage to zero, effectively
removing common-mode voltages from the transmission line. This technique improves CMR for systems
with imperfectly balanced transmission-line impedances.
1.4k
OUT+
700Ω
IN+
Figure 3. MAX4142 Shutdown Equivalent Circuit
Shutdown Mode
The MAX4142 can be put into low-power shutdown
mode by driving SHDN high. The amplifier output is
high impedance in this mode; thus the impedance at
OUT is that of the feedback resistors (2.8kΩ) (Figure 3).
_______________________________________________________________________________________
7
MAX4142
250MHz, Low-Power, High-Output-Current,
Differential Line Driver
5
IN+
MAX4142
A1
4
OUT+
3
GAIN (dB)
2
RF
SENSE+
RG
RL
CL = 5pF
CL = 10pF
-3
-4
RG
-5
SENSE-
100k
RF
1M
10M
100M
1G
FREQUENCY (Hz)
OUT-
A2
Figure 5. MAX4142 Small-Signal Response with Capacitive
Load
IN-
Figure 4. Connection of SENSE+ and SENSE- to a Remote
Load
Using SENSE+ and SENSEThe MAX4142 has two output voltage-sense pins,
SENSE+ and SENSE-. These pins are normally connected to the MAX4142’S OUT+ and OUT- pins. In
some long-line applications, it may be desirable to connect SENSE+ to OUT+ and SENSE- to OUT- at the
load, instead of the typical connection at the part
(Figure 4). This compensates for the long line’s resistance, which otherwise leads to an IR voltage error.
When using this technique, keep the sense lines’
impedance low to minimize gain errors. Also, keep
capacitance low to maximize frequency response. The
gain of the MAX4142 is approximated by the following
equation:
(
) (
 RF + ∆RSENSE + + ∆RSENSE −
AV = 1 + 
RG

) 

where ∆RSENSE+ and ∆RSENSE- are the SENSE+ and
SENSE- trace impedances, respectively. For the
MAX4142, RF is 700Ω and RG is 700Ω.
Additionally, mismatches in the SENSE+ and SENSEtraces lead to common-mode gain errors. However,
these errors are effectively eliminated by the
MAX4142’s common-mode feedback (see the
Common-Mode Feedback section).
8
0
-1
-2
GND
A3
CL = 15pF
1
Driving Capacitive Loads
The MAX4142 provides maximum AC performance
when driving no output load capacitance. This is the
case when driving a correctly terminated transmission
line (i.e., a back-terminated cable).
In most amplifier circuits, driving large-load capacitance increases the chance of oscillations. The amplifier’s output impedance and the load capacitor combine
to add a pole and excess phase to the loop response.
If the pole’s frequency is low enough and phase margin
is degraded sufficiently, oscillations may occur. A second concern when driving capacitive loads results from
the amplifier’s output impedance, which looks inductive
at high frequencies. The inductance forms an L-C resonant circuit with the capacitive load. This causes peaking in the frequency response and degrades the
amplifier’s phase margin.
The MAX4142 drives capacitive loads up to 25pF without oscillation. However, some peaking may occur in
the frequency domain (Figure 5).
To drive larger-capacitance loads or to reduce ringing,
add isolation resistors between the amplifier’s outputs
and the load (Figure 6).
The value of R ISO depends on the capacitive load
(Figure 7). With higher capacitive values, bandwidth is
dominated by the RC network formed by RISO and CL;
the bandwidth of the amplifier itself is much higher.
Also note that the isolation resistor forms a divider that
decreases the voltage delivered to the load.
_______________________________________________________________________________________
250MHz, Low-Power, High-Output-Current,
Differential Line Driver
MAX4142
25
MAX4142
A1
RL = 150Ω
OUT+
RISO
CLOAD
RF
RLOAD
SENSE+
RG
A3
GND
ISOLATION RESISTANCE (Ω)
IN+
20
15
10
5
RG
0
SENSE-
0
RF
A2
IN-
50 100 150 200 250 300 350 400 450 500
CAPACITIVE LOAD (pF)
OUTRISO
Figure 7. Isolation Resistance vs. Capacitive Load
CLOAD
RLOAD
Figure 6. Addition of RISO to Amplifier Output
___________________Chip Information
TRANSISTOR COUNT: 243
SUBSTRATE CONNECTED TO VEE
_______________________________________________________________________________________
9
________________________________________________________Package Information
SOICN.EPS
MAX4142
250MHz, Low-Power, High-Output-Current,
Differential Line Driver
10
______________________________________________________________________________________
250MHz, Low-Power, High-Output-Current,
Differential Line Driver
______________________________________________________________________________________
MAX4142
NOTES
11
MAX4142
250MHz, Low-Power, High-Output-Current,
Differential Line Driver
NOTES
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 1998 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.