_______________General Description
The MAX4178/MAX4278 are ±5V, wide-bandwidth, fastsettling, closed-loop buffers featuring high slew rate, high
precision, high output current, low noise, and low differential gain and phase errors. The MAX4178, with a -3dB
bandwidth of 330MHz, is preset for unity voltage gain
(0dB). The MAX4278 is preset for a voltage gain of +2
(6dB) and has a 310MHz -3dB bandwidth.
The MAX4178/MAX4278 feature the high slew rate and
low power that are characteristic of current-mode feedback amplifiers. However, unlike conventional currentmode feedback amplifiers, these devices have a
unique input stage that combines the benefits of current-feedback topology with those of the traditional voltage-feedback topology. This combination results in low
input offset voltage and bias current, low noise, and
high gain precision and power-supply rejection.
The MAX4178/MAX4278 are ideally suited for driving
50Ω or 75Ω loads. They are the perfect choice for highspeed cable-driving applications, such as video routing.
The MAX4178/MAX4278 are available in DIP, SO, and
space-saving µMAX and SOT23 packages.
________________________Applications
Broadcast and High-Definition TV Systems
Video Switching and Routing
High-Speed Cable Drivers
Communications
Medical Imaging
Precision High-Speed DAC/ADC Buffers
____________________________Features
♦ High Speed:
330MHz -3dB Bandwidth (MAX4178)
310MHz -3dB Bandwidth (MAX4278)
250MHz Full-Power Bandwidth (V
OUT
= 2Vp-p)
150MHz 0.1dB Flatness Bandwidth
1300V/µs Slew Rate (MAX4178)
1600V/µs Slew Rate (MAX4278)
♦ Low Differential Phase/Gain Error: 0.01°/0.04%
♦ 8mA Supply Current
♦ 1µA Input Bias Current
♦ 0.5mV Input Offset Voltage
♦ 5nV/
√
HHzz
Input-Referred Voltage Noise
♦ 2pA/
√
HHzz
Input-Referred Current Noise
♦ 1.0% Max Gain Error with 100Ω Load
♦ Short-Circuit Protected
♦ 8000V ESD Protection
♦ Available in Space-Saving SOT23 Package
MAX4178/MAX4278
330MHz, Gain of +1/Gain of +2
Closed-Loop Buffers
________________________________________________________________
Maxim Integrated Products
1
19-0468; Rev 1; 5/97
PART
MAX4178EPA
MAX4178ESA
MAX4178EUA -40°C to +85°C
-40°C to +85°C
-40°C to +85°C
TEMP. RANGE
PINPACKAGE
8 Plastic DIP
8 SO
8 µMAX
EVALUATION KIT MANUAL
FOLLOWS DATA SHEET
______________Ordering Information
Ordering Information continued at end of data sheet.
DIP/SO/µMAX
TOP VIEW
OUT
IN
N.C.
V
EE
1
2
8
7
N.C.
V
CC
GND
N.C.
MAX4178
MAX4278
3
4
6
5
V
EE
GNDIN
15V
CC
OUT
SOT23-5
2
34
MAX4178
MAX4278
MAX4278
V
IN
75Ω
75Ω
V
OUT
75Ω
VIDEO/RF CABLE DRIVER
_________________Pin Configurations
__________Typical Operating Circuit
MAX4178MJA -55°C to +125°C 8 CERDIP
MAX4178EUK-T -40°C to +85°C 5 SOT23
SOT
TOP MARK
–
–
–
–
ABYX
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.
MAX4178/MAX4278
330MHz, Gain of +1/Gain of +2
Closed-Loop Buffers
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
DC ELECTRICAL CHARACTERISTICS
(VCC= +5V, VEE= -5V, V
OUT
= 0V, RL= ∞, TA= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at TA= +25°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.
Supply Voltage (VCCto VEE)..................................................12V
Input Voltage....................................(V
CC
+ 0.3V) to (VEE- 0.3V)
Output Short-Circuit Duration (to GND) .....................Continuous
Continuous Power Dissipation (T
A
= +70°C)
Plastic DIP (derate 9.09mW/°C above +70°C) ...........727mW
SO (derate 5.88mW/°C above +70°C)........................471mW
µMAX (derate 4.10mW/°C above +70°C) ...................330mW
CERDIP (derate 8.00mW/°C above +70°C)................640mW
SOT23 (derate 7.10mW/°C above +70°C)..................571mW
Operating Temperature Ranges (Note 1)
MAX4178E_A/MAX4278E_A...........................-40°C to +85°C
MAX4178EUK/MAX4278EUK .........................-40°C to +85°C
MAX4178MJA/MAX4278MJA .......................-55°C to +125°C
Storage Temperature Range.............................-65°C to +160°C
Lead Temperature (soldering, 10sec).............................+300°C
CONDITIONS
UNITSMIN TYP MAXSYMBOLPARAMETER
MAX4178 ±2.5 ±3.0
MAX4278
V
±1.25 ±1.5
V
IN
Input Voltage Range
0.5 2.0
µV/°C2TCV
OS
Input Offset Voltage Drift
1 3
µAI
B
Input Bias Current
MΩ1R
IN
Input Resistance
VS= ±4.5V to ±5.5V dB70 90PSRR
Power-Supply Rejection
Ratio
0.990 1.000
MAX4178 (Note 2)
0.985 1.000
1.98 2.01
MAX4278 (Note 3)
V/V
1.97 2.01
A
V
Voltage Gain
V
OUT
= ±1mV to ±2V %0.01A
V(LIN)
Gain Linearity
f = DC Ω0.1R
OUT
Output Resistance
Short to GND mA150I
SC
Short-Circuit Output Current
RL= 100Ω ±2.5 ±3.0
TA = +25°C
RL= 100Ω
RL= 50Ω
RL= 100Ω
RL= 50Ω
RL= 50Ω
V
±2.0 ±2.5
V
OUT
Output Voltage Swing
TA= +25°C 8 10
12
mA
14
TA = T
MIN
to T
MAX
I
SY
Quiescent Supply Current
MAX4_78E_ _
MAX4_78MJA
TA = -40°C to +85°C mA70 100I
OUT
Minimum Output Current
3.0
TA = T
MIN
to T
MAX
5
Note 2: Voltage Gain = (V
OUT
- VOS) / VINmeasured at VIN= ±2.5V.
Note 3: Voltage Gain = (V
OUT
- VOS) / VINmeasured at VIN= ±1.25V.
TA = +25°C
0.5 3.0
TA =
T
MIN
to T
MAX
5.0
mVV
OS
Input Offset Voltage
MAX4_78ESA/EPA/EUA/MJA
MAX4_78EUK
MAX4_78ESA/EPA/EUA/MJA
MAX4_78EUK
Note 1: Specifications for the MAX4_78EUK(SOT23 packages) are 100% tested at TA= +25°C, and guaranteed by design over
temperature.
MHz
MAX4178/MAX4278
330MHz, Gain of +1/Gain of +2
Closed-Loop Buffers
_______________________________________________________________________________________ 3
AC ELECTRICAL CHARACTERISTICS
(VCC= +5V, VEE= -5V, RL= 100Ω, TA= +25°C, unless otherwise noted.)
Note 4: Minimum AC specifications are guaranteed by sample test on the MAX4_78ESA only.
Note 5: Tested with a 3.58MHz video test signal with an amplitude of 40IRE superimposed on a linear ramp (0 to 100IRE). An IRE is
a unit of video signal amplitude developed by the Institute of Radio Engineers. 140IRE = 1V in color systems.
240 330
230 310
CONDITIONS
V
OUT
= 2V step ns2tR, t
F
Rise/Fall Times
f = 10MHz nV/√Hz5e
n
Input Voltage Noise Density
f = 10MHz pA/√Hz2i
n
Input Current Noise Density
0.04
f = 3.58MHz %
0.04
DG
Differential Gain
(Note 5)
f = 5MHz, V
OUT
= 2Vp-p dBC
-81
SFDRSpurious-Free Dynamic Range
36
fC= 10MHz,
V
OUT
= 2Vp-p
dBm
31
IP3Third-Order Intercept
UNITSMIN TYP MAXPARAMETER
MAX4278
30 150MAX4178
MAX4278
250
V
OUT
= 2Vp-p MHz
250
FPBWFull-Power Bandwidth
MAX4178
to 0.01%
10
V
OUT
= 2V step ns
12
t
S
Settling Time
to 0.1%
MAX4178
MAX4278
0.01
MAX4278
MAX4178
f = 3.58MHz degrees
0.01
DP
Differential Phase
(Note 5)
-58
MAX4278
MAX4178
fC= 10MHz,
V
OUT
= 2Vp-p
dB
-59
THDTotal Harmonic Distortion
MAX4178
MAX4278
pF1C
IN
Input Capacitance
MAX4178
MAX4278 -74
MAX4178
MAX4278
30 150
SYMBOL
800 1300MAX4178
900 1600MAX4278
V/µsV
OUT
= ±2Vp-pSR
Slew Rate
(Note 4)
MHz
V
OUT
≤
0.1Vp-p
BW
Small-Signal, -3dB Bandwidth
(Note 4)
MHz
V
OUT
≤
0.1Vp-p
BW
(0.1dB)
Small-Signal, ±0.1dB Bandwidth
(Note 4)
MAX4178/MAX4278
330MHz, Gain of +1/Gain of +2
Closed-Loop Buffers
4 _______________________________________________________________________________________
__________________________________________Typical Operating Characteristics
(VCC= +5V, VEE= -5V, RL= 100Ω, CL= 0pF, TA = +25°C, unless otherwise noted.)
2
-8
1M
10M
100M
1G
MAX4178
SMALL-SIGNAL GAIN vs. FREQUENCY
-5
-6
-7
0
-1
-2
-3
-4
1
MAX4178/4278-01
FREQUENCY (Hz)
GAIN (dB)
-0.7
1M
10M
100M
1G
MAX4178
GAIN FLATNESS vs. FREQUENCY
-0.4
-0.5
-0.6
-0.8
0.1
0
-0.1
-0.2
-0.3
0.2
MAX4178/4278-02
FREQUENCY (Hz)
GAIN (dB)
-6
1M
10M
100M
1G
MAX4178
LARGE-SIGNAL GAIN vs. FREQUENCY
-3
-4
-5
-7
2
1
0
-1
-2
3
MAX4178/4278-03
FREQUENCY (Hz)
GAIN (dB)
VO = 2Vp-p
-1
1M
10M
100M
1G
MAX4278
SMALL-SIGNAL GAIN vs. FREQUENCY
2
1
0
-2
7
6
5
4
3
8
MAX4178/4278-04
FREQUENCY (Hz)
GAIN (dB)
5.3
1M
10M
100M
1G
MAX4278
GAIN FLATNESS vs. FREQUENCY
5.6
5.5
5.4
5.2
6.1
6.0
5.9
5.8
5.7
6.2
MAX4178/4278-05
FREQUENCY (Hz)
GAIN (dB)
-6
1M
10M
100M
1G
MAX4278
LARGE-SIGNAL GAIN vs. FREQUENCY
0
-2
-4
-8
10
8
6
4
2
12
MAX4178/4278-06
FREQUENCY (Hz)
GAIN (dB)
VO = 2Vp-p
MAX4178 LARGE-SIGNAL
PULSE RESPONSE (C
L
= 0pF)
MAX4178/4278-08
TIME (10ns/div)
VOLTAGE (2V/div)
IN
OUT
GND
GND
MAX4278 SMALL-SIGNAL
PULSE RESPONSE (C
L
= 0pF)
MAX4178/4278-09
TIME (10ns/div)
VOLTAGE
IN
(50mV/
div)
OUT
(100mV/
div)
GND
GND
MAX4178 SMALL-SIGNAL
PULSE RESPONSE (C
L
= 0pF)
MAX4178/4278-07
TIME (10ns/div)
VOLTAGE (100mV/div)
IN
OUT
GND
GND
MAX4178/MAX4278
330MHz, Gain of +1/Gain of +2
Closed-Loop Buffers
_______________________________________________________________________________________
5
MAX4278 LARGE-SIGNAL
PULSE RESPONSE (C
L
= 0pF)
MAX4178/4278-10
TIME (10ns/div)
VOLTAGE
IN
(1V/div)
OUT
(2V/div)
GND
GND
MAX4178 SMALL-SIGNAL
PULSE RESPONSE (C
L
= 50pF)
MAX4178/4278-11
TIME (20ns/div)
VOLTAGE (100mV/div)
IN
OUT
GND
GND
MAX4178 LARGE-SIGNAL
PULSE RESPONSE (C
L
= 50pF)
MAX4178/4278-12
TIME (20ns/div)
VOLTAGE (2V/div)
IN
OUT
GND
GND
MAX4178 SMALL-SIGNAL
PULSE RESPONSE (C
L
= 100pF)
MAX4178/4278-13
TIME (20ns/div)
VOLTAGE (100mV/div)
IN
OUT
GND
GND
MAX4178 LARGE-SIGNAL
PULSE RESPONSE (C
L
= 100pF)
MAX4178/4278-14
TIME (20ns/div)
VOLTAGE (2V/div)
IN
OUT
GND
GND
MAX4278 SMALL-SIGNAL
PULSE RESPONSE (C
L
= 50pF)
MAX4178/4278-15
TIME (20ns/div)
VOLTAGE
IN
(50mV/
div)
OUT
(100mV/
div)
GND
GND
____________________________Typical Operating Characteristics (continued)
(VCC= +5V, VEE= -5V, RL= 100Ω, CL= 0pF, TA = +25°C, unless otherwise noted.)
MAX4278 LARGE-SIGNAL
PULSE RESPONSE (C
L
= 50pF)
MAX4178/4278-16
TIME (20ns/div)
VOLTAGE
IN
(1V/div)
OUT
(2V/div)
GND
GND
MAX4278 SMALL-SIGNAL
PULSE RESPONSE (C
L
= 100pF)
MAX4178/4278-17
TIME (20ns/div)
VOLTAGE
IN
(50mV/
div)
OUT
(100mV/
div)
GND
GND
MAX4278 LARGE-SIGNAL
PULSE RESPONSE (C
L
= 100pF)
MAX4178/4278-18
TIME (20ns/div)
VOLTAGE
IN
(1V/div)
OUT
(2V/div)
GND
GND
MAX4178/MAX4278
330MHz, Gain of +1/Gain of +2
Closed-Loop Buffers
6 _______________________________________________________________________________________
____________________________Typical Operating Characteristics (continued)
(VCC= +5V, VEE= -5V, RL= 100Ω, CL= 0pF, TA = +25°C, unless otherwise noted.)
0.00
-0.02
0.02
-0.010
0 100
100
MAX4178
DIFFERENTIAL PHASE/GAIN
-0.006
-0.008
-0.04
-0.06
IRE
IRE
DIFF PHASE (deg)
DIFF GAIN (%)
0.002
0.000
-0.004
-0.002
MAX4178/4278-19
0
R
L
= 150Ω
RL = 150Ω
0.00
0.01
-0.02
-0.03
-0.01
0.02
-0.006
0 100
100
MAX4278
DIFFERENTIAL PHASE/GAIN
-0.004
-0.04
-0.05
-0.06
IRE
IRE
DIFF PHASE (deg)
DIFF GAIN (%)
0.002
-0.002
0.000
MAX4178/4278-20
0
R
L
= 150Ω
RL = 150Ω
-20
-100
1k 10k 1M 10M100k 100M
MAX4178 HARMONIC DISTORTION
vs. FREQUENCY
-80
MAX4178/4278-21
FREQUENCY (Hz)
DISTORTION (dB)
-60
-40
TOTAL HARMONIC DISTORTION
SECOND HARMONIC
THIRD HARMONIC
-40
-100
10k 1M 10M100k 100M
MAX4278 HARMONIC DISTORTION
vs. FREQUENCY
-90
MAX4178/4278-22
FREQUENCY (Hz)
DISTORTION (dB)
-80
-70
-60
-50
2nd HARMONIC
TOTAL HARMONIC DISTORTION
3rd HARMONIC
-50
INPUT OFFSET VOLTAGE (VOS)
vs. TEMPERATURE
MAX4178/4278-25
TEMPERATURE (˚C)
INPUT OFFSET VOLTAGE (µV)
-200
-300
-100
0
100
200
300
400
-25 0 25 50 75 125100
VIN = 0V
-30
-20
-110
-50
-70
-90
30k 100k 1M 10M 100M
POWER-SUPPLY REJECTION
vs. FREQUENCY
-100
MAX4178/4278-23
FREQUENCY (Hz)
POWER-SUPPLY REJECTION (dB)
-80
-60
-40
MAX4278
MAX4178
1k
0.1
100k 1M 10M 100M 500M
OUTPUT IMPEDANCE
vs. FREQUENCY
1
MAX4178/4278-24
FREQUENCY (Hz)
OUTPUT IMPEDANCE (Ω)
10
100
MAX4278
MAX4178
-50
QUIESCENT SUPPLY CURRENT (ISY)
vs. TEMPERATURE
MAX4178/4278-26
TEMPERATURE (˚C)
QUIESCENT SUPPLY CURRENT (mA)
2
0
4
6
8
10
12
14
-25 0 25 50 75 125100
-50
INPUT BIAS CURRENT (IB)
vs. TEMPERATURE
MAX4178/4278-27
TEMPERATURE (˚C)
INPUT BIAS CURRENT (µA)
0.5
0
1.0
1.5
2.0
2.5
3.0
3.5
-25 0 25 50 75 125100
V
IN
= 0V
_______________Detailed Description
The MAX4178/MAX4278 are ±5V, wide-bandwidth,
fast-settling, closed-loop buffers featuring high slew
rate, high precision, high output current, low noise, and
low differential gain and phase errors. The MAX4178,
with a -3dB bandwidth of 330MHz, is preset for unity voltage gain (0dB). The MAX4278 is preset for a voltage gain
of +2 (6dB) and has a 310MHz -3dB bandwidth.
These devices have a unique input stage that combines the benefits of a current-mode-feedback topology (high slew rate and low power) with those of a
traditional voltage-feedback topology. This combination
of architectures results in low input offset voltage and
bias current, and high gain precision and power-supply
rejection.
Under short-circuit conditions, the output current is typically limited to 150mA. This is low enough that a short
to ground of any duration will not cause permanent
damage to the chip. However, a short to either supply
will create double the allowable power dissipation and
may cause permanent damage if allowed to exist for
longer than approximately 10 seconds. The high output-current capability is an advantage in systems that
transmit a signal to several loads. See
High-
Performance Video Distribution Amplifier
in the
Applications Information
section.
MAX4178/MAX4278
330MHz, Gain of +1/Gain of +2
Closed-Loop Buffers
_______________________________________________________________________________________ 7
-50
OUTPUT VOLTAGE SWING
vs. TEMPERATURE
MAX4178/4278-28
TEMPERATURE (˚C)
OUTPUT VOLTAGE SWING (±V)
3.0
2.5
3.5
4.0
-25 0 25 50 75 125100
RL =
RL = 100Ω
RL = 50Ω
8
-50
INPUT VOLTAGE RANGE
vs. TEMPERATURE
MAX4178/4278-29
TEMPERATURE (˚C)
INPUT VOLTAGE RANGE (±V)
2.0
3.5
3.0
2.5
1.5
1.0
4.0
4.5
MAX4178
MAX4278
-25 0 25 50 75 125100
____________________________Typical Operating Characteristics (continued)
(VCC= +5V, VEE= -5V, RL= 100Ω, CL= 0pF, TA = +25°C, unless otherwise noted.)
_____________________Pin Description
1
5
2
3
4
—
Output6
Positive Power Supply.
Connect to +5V.
7
Negative Power Supply.
Connect to -5V.
4
Input3
Ground2
No Connection1, 5, 8
PIN
OUT
V
CC
V
EE
IN
GND
N.C.
NAME
SOT23SO/µMAX/DIP
FUNCTION
__________Applications Information
Grounding, Bypassing,
and PC Board Layout
In order to obtain the MAX4178/MAX4278’s full 330MHz/
310MHz bandwidths, Micro-Strip and Stripline techniques are recommended in most cases. To ensure
that the PC board does not degrade the amplifier’s performance, it’s a good idea to design the board for a frequency greater than 1GHz. Even with very short traces,
it’s good practice to use these techniques at critical
points, such as inputs and outputs. Whether you use a
constant-impedance board or not, observe the following guidelines when designing the board:
• Do not use wire-wrap boards. They are too inductive.
• Do not use IC sockets. They increase parasitic
capacitance and inductance.
• In general, surface-mount components have shorter
leads and lower parasitic reactance, giving better
high-frequency performance than through-hole components.
• The PC board should have at least two layers, with
one side a signal layer and the other a ground plane.
• Keep signal lines as short and straight as possible.
Do not make 90° turns; round all corners.
• The ground plane should be as free from voids as
possible.
On Maxim’s evaluation kit, the ground plane has been
removed from areas where keeping the trace capacitance to a minimum is more important than maintaining
ground continuity.
Driving Capacitive Loads
The MAX4178/MAX4278 provide maximum AC performance with no output load capacitance. This is the
case when the MAX4178/MAX4278 are driving a correctly terminated transmission line (e.g., a back-terminated 75Ω cable). However, the MAX4178/MAX4278
are capable of driving capacitive loads up to 100pF
without oscillations, but with reduced AC performance
Driving large capacitive loads increases the chance of
oscillations in most amplifier circuits. This is especially
true for circuits with high loop gains, such as voltage
followers. The amplifier’s output resistance and the load
capacitor combine to add a pole and excess phase to
the loop response. If the frequency of this pole is low
enough and if phase margin is degraded sufficiently,
oscillations may occur.
A second problem when driving capacitive loads
results from the amplifier’s output impedance, which
looks inductive at high frequency. This inductance
forms an L-C resonant circuit with the capacitive load,
which causes peaking in the frequency response and
degrades the amplifier’s gain margin.
The MAX4178/MAX4278 drive capacitive loads up to
100pF without oscillation. However, some peaking (in
the frequency domain) or ringing (in the time domain)
may occur. This is shown in Figures 2a and 2b and the
in the Small- and Large-Signal Pulse Response graphs
in the
Typical Operating Characteristics
.
To drive larger-capacitance loads or to reduce ringing,
add an isolation resistor between the amplifier’s output
and the load, as shown in Figure 1.
The value of R
ISO
depends on the circuit’s gain and the
capacitive load. Figures 3a and 3b show the Bode
plots that result when a 20Ω isolation resistor is used
with a voltage follower driving a range of capacitive
loads. At the higher capacitor values, the bandwidth is
dominated by the RC network, formed by R
ISO
and CL;
the bandwidth of the amplifier itself is much higher.
Note that adding an isolation resistor degrades gain
accuracy. The load and isolation resistor form a divider
that decreases the voltage delivered to the load.
MAX4178/MAX4278
330MHz, Gain of +1/Gain of +2
Closed-Loop Buffers
8 _______________________________________________________________________________________
MAX4178
MAX4278
V
IN
R
ISO
V
OUT
C
L
R
L
Figure 1. Capacitive-Load Driving Circuit
MAX4178/MAX4278
330MHz, Gain of +1/Gain of +2
Closed-Loop Buffers
_______________________________________________________________________________________ 9
8
7
6
-2
1M 100M 1G
AND ISOLATION RESISTOR
1
0
-1
5
4
3
2
MAX4178/4278-3b
FREQUENCY (Hz)
GAIN (dB)
10M
R
ISO
= 20Ω
CL = 100pF
CL = 47pF
CL = 22pF
CL = 0pF
Figure 3b. MAX4278 Small-Signal Gain vs. Frequency with
Capacitive Load and Isolation Resistor (R
ISO
)
20
15
10
-30
1M 100M 1G
FREQUENCY WITH CAPACITIVE LOAD
-15
-20
-25
5
0
-5
-10
MAX4178/4278-2a
FREQUENCY (Hz)
GAIN (dB)
10M
R
ISO
= 0Ω CL = 100pF
CL = 47pF
CL = 22pF
CL = 0pF
Figure 2a. MAX4178 Small-Signal Gain vs. Frequency with
Capacitive Load
26
21
16
-24
1M 100M 1G
MAX4278 SMALL SIGNAL GAIN vs.
FREQUENCY WITH CAPACITIVE LOAD
-9
-14
-19
11
6
1
-4
MAX4178/4278-2b
FREQUENCY (Hz)
GAIN (dB)
10M
R
ISO
= 0Ω CL = 100pF
CL = 47pF
CL = 22pF
CL = 0pF
Figure 2b. MAX4278 Small-Signal Gain vs. Frequency with
Capacitive Load
2
1
0
-8
1M 100M 1G
AND ISOLATION RESISTOR
-5
-6
-7
-1
-2
-3
-4
MAX4178/4278-3a
FREQUENCY (Hz)
GAIN (dB)
10M
R
ISO
= 20Ω
CL = 100pF
CL = 47pF
CL = 22pF
CL = 0pF
Figure 3a. MAX4178 Small-Signal Gain vs. Frequency with
Capacitive Load and Isolation Resistor (R
ISO
)
MAX4178/MAX4278
Flash ADC Preamp
The MAX4178/MAX4278’s high current-drive capability
makes them well suited for buffering the low-impedance input of a high-speed flash ADC. With their low
output impedance, these buffers can drive the inputs of
the ADC with no loss of accuracy. Figure 4 shows a
preamp for digitizing video, using the 250Msps
MAX100 and the 500Msps MAX101 flash ADCs. Both of
these ADCs have a 50Ω input resistance and a 1.2GHz
input bandwidth.
High-Performance
Video Distribution Amplifier
The MAX4278 (AV= +2) makes an excellent driver for
multiple back-terminated 75Ω video coaxial cables
(Figure 5). The high current-output capability allows the
attachment of up to six ±2Vp-p, 150Ω loads to the
MAX4278 at +25°C. With the output limited to ±1Vp-p,
the number of loads may double. For multiple gain-of-2
video line drivers in a single package, see the
MAX496/MAX497data sheet.
330MHz, Gain of +1/Gain of +2
Closed-Loop Buffers
10 ______________________________________________________________________________________
MAX4178
MAX4278
VIDEO IN
FLASH ADC
(MAX100/MAX101)
Figure 4. Preamp for Video Digitizer
MAX4278
VIDEO IN
75Ω
75Ω
75Ω
75Ω
75Ω
75Ω
75Ω
75Ω
75Ω
OUT1
OUT2
OUTN
Figure 5. High-Performance Video Distribution Amplifier
___________________Chip Information
TRANSISTOR COUNT: 175
SUBSTRATE CONNECTED TO V
EE
_Ordering Information (continued)
PART
MAX4278EPA
MAX4278ESA
MAX4278EUA -40°C to +85°C
-40°C to +85°C
-40°C to +85°C
TEMP. RANGE
PINPACKAGE
8 Plastic DIP
8 SO
8 µMAX
MAX4278MJA -55°C to +125°C 8 CERDIP
MAX4278EUK-T -40°C to +85°C 5 SOT23
SOT
TOP MARK
–
–
–
–
ABYY
MAX4178/MAX4278
330MHz, Gain of +1/Gain of +2
Closed-Loop Buffers
______________________________________________________________________________________ 11
________________________________________________________Package Information
PDIPN.EPS
SOICN.EPS
MAX4178/MAX4278
330MHz, Gain of +1/Gain of +2
Closed-Loop Buffers
12 ______________________________________________________________________________________
___________________________________________Package Information (continued)
8LUMAXD.EPS
SOT5L.EPS
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