Maxim MAX4178 330mhz, gain of 1/gain of @ closed-loop buffer Datasheet

19-0468; Rev 1; 5/97
NUAL
KIT MA
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FO
330MHz, Gain of +1/Gain of +2
Closed-Loop Buffers
____________________________Features
♦ High Speed:
330MHz -3dB Bandwidth (MAX4178)
310MHz -3dB Bandwidth (MAX4278)
250MHz Full-Power Bandwidth (VOUT = 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/√Hz Input-Referred Voltage Noise
♦ 2pA/√Hz Input-Referred Current Noise
♦ 1.0% Max Gain Error with 100Ω Load
♦ Short-Circuit Protected
♦ 8000V ESD Protection
♦ Available in Space-Saving SOT23 Package
________________________Applications
______________Ordering Information
Broadcast and High-Definition TV Systems
Video Switching and Routing
TEMP. RANGE
PINPACKAGE
MAX4178EPA
-40°C to +85°C
8 Plastic DIP
MAX4178ESA
MAX4178EUA
MAX4178EUK-T
MAX4178MJA
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
8 SO
8 µMAX
5 SOT23
8 CERDIP
PART
High-Speed Cable Drivers
Communications
Medical Imaging
Precision High-Speed DAC/ADC Buffers
SOT
TOP MARK
–
–
–
ABYX
–
Ordering Information continued at end of data sheet.
__________Typical Operating Circuit
_________________Pin Configurations
TOP VIEW
75Ω
VIN
VOUT
OUT 1
MAX4278
VEE 2
75Ω
5
VCC
GND 2
MAX4178
MAX4278
IN 3
75Ω
IN 3
VIDEO/RF CABLE DRIVER
4
SOT23-5
N.C. 1
GND
MAX4178
MAX4278
VEE 4
8
N.C.
7
VCC
6
OUT
5
N.C.
DIP/SO/µMAX
________________________________________________________________ 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.
MAX4178/MAX4278
_______________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.
MAX4178/MAX4278
330MHz, Gain of +1/Gain of +2
Closed-Loop Buffers
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (VCC to VEE) ..................................................12V
Input Voltage....................................(VCC + 0.3V) to (VEE - 0.3V)
Output Short-Circuit Duration (to GND) .....................Continuous
Continuous Power Dissipation (TA = +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
Note 1: Specifications for the MAX4_78EUK(SOT23 packages) are 100% tested at TA = +25°C, and guaranteed by design over
temperature.
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, VOUT = 0V, RL = ∞, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
Input Voltage Range
SYMBOL
VIN
MIN
TYP
MAX4178
±2.5
±3.0
MAX4278
±1.25
±1.5
CONDITIONS
TA = +25°C
Input Offset Voltage
Input Offset Voltage Drift
Input Bias Current
Input Resistance
Power-Supply Rejection
Ratio
VOS
TA =
TMIN to TMAX
0.5
2.0
MAX4_78EUK
0.5
3.0
MAX4_78ESA/EPA/EUA/MJA
TA = +25°C
TA = TMIN to TMAX
AV
AV(LIN)
Quiescent Supply Current
ISY
MΩ
90
dB
0.990
0.985
1.98
1.97
1.000
1.000
2.01
2.01
0.01
%
Ω
mA
150
mA
RL = 100Ω
±2.5
±3.0
RL = 50Ω
TA = +25°C
±2.0
±2.5
8
Short to GND
TA = TMIN to TMAX
MAX4_78E_ _
MAX4_78MJA
Note 2: Voltage Gain = (VOUT - VOS) / VIN measured at VIN = ±2.5V.
Note 3: Voltage Gain = (VOUT - VOS) / VIN measured at VIN = ±1.25V.
2
V/V
0.1
TA = -40°C to +85°C
VOUT
1
100
f = DC
IOUT
Output Voltage Swing
RL = 100Ω
RL = 50Ω
RL = 100Ω
RL = 50Ω
µA
70
ROUT
Minimum Output Current
ISC
70
VOUT = ±1mV to ±2V
Output Resistance
Short-Circuit Output Current
µV/°C
3
5
VS = ±4.5V to ±5.5V
MAX4278 (Note 3)
Gain Linearity
1
RIN
PSRR
mV
5.0
2
MAX4178 (Note 2)
Voltage Gain
3.0
MAX4_78EUK
UNITS
V
MAX4_78ESA/EPA/EUA/MJA
TCVOS
IB
MAX
_______________________________________________________________________________________
V
10
12
14
mA
330MHz, Gain of +1/Gain of +2
Closed-Loop Buffers
(VCC = +5V, VEE = -5V, RL = 100Ω, TA = +25°C, unless otherwise noted.)
PARAMETER
Small-Signal, -3dB Bandwidth
(Note 4)
Small-Signal, ±0.1dB Bandwidth
(Note 4)
Full-Power Bandwidth
SYMBOL
BW
VOUT ≤
0.1Vp-p
BW(0.1dB)
VOUT ≤
0.1Vp-p
FPBW
CONDITIONS
MIN
TYP
MAX4178
MAX4278
MAX4178
MAX4278
240
230
30
30
MAX4178
330
310
150
150
250
MAX4278
250
VOUT = 2Vp-p
MAX4178
800
1300
MAX4278
900
1600
MAX
UNITS
MHz
MHz
MHz
MHz
Slew Rate
(Note 4)
SR
VOUT = ±2Vp-p
Settling Time
tS
VOUT = 2V step
Rise/Fall Times
tR, tF
VOUT = 2V step
Input Capacitance
CIN
Input Voltage Noise Density
en
f = 10MHz
5
nV/√Hz
Input Current Noise Density
in
f = 10MHz
2
pA/√Hz
Differential Gain
(Note 5)
DG
f = 3.58MHz
Differential Phase
(Note 5)
DP
f = 3.58MHz
Total Harmonic Distortion
THD
fC = 10MHz,
VOUT = 2Vp-p
Spurious-Free Dynamic Range
SFDR
f = 5MHz, VOUT = 2Vp-p
Third-Order Intercept
IP3
fC = 10MHz,
VOUT = 2Vp-p
to 0.1%
10
to 0.01%
12
V/µs
ns
2
ns
1
pF
MAX4178
0.04
MAX4278
0.04
MAX4178
0.01
MAX4278
0.01
MAX4178
-58
MAX4278
-59
MAX4178
-81
MAX4278
-74
MAX4178
36
MAX4278
31
%
degrees
dB
dBC
dBm
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.
_______________________________________________________________________________________
3
MAX4178/MAX4278
AC ELECTRICAL CHARACTERISTICS
__________________________________________Typical Operating Characteristics
(VCC = +5V, VEE = -5V, RL = 100Ω, CL = 0pF, TA = +25°C, unless otherwise noted.)
1
0
0.1
0
-3
-4
0
-0.2
-0.3
-0.4
-1
-2
-3
-5
-0.5
-4
-6
-0.6
-5
-7
-0.7
-6
-8
-0.8
-7
1M
10M
100M
1G
1M
10M
100M
1M
1G
10M
100M
1G
FREQUENCY (Hz)
FREQUENCY (Hz)
FREQUENCY (Hz)
MAX4278
SMALL-SIGNAL GAIN vs. FREQUENCY
MAX4278
GAIN FLATNESS vs. FREQUENCY
MAX4278
LARGE-SIGNAL GAIN vs. FREQUENCY
6.0
5
12
8
2
6
GAIN (dB)
GAIN (dB)
3
5.8
5.7
5.6
4
2
0
1
5.5
-2
-4
0
5.4
-1
5.3
-6
-2
5.2
-8
1M
10M
100M
1G
1M
FREQUENCY (Hz)
10M
100M
1G
1M
FREQUENCY (Hz)
OUT
GND
100M
1G
MAX4278 SMALL-SIGNAL
PULSE RESPONSE (CL = 0pF)
MAX4178/4278-08
IN
GND
IN
(50mV/
div)
GND
OUT
GND
OUT
(100mV/
div)
GND
VOLTAGE
GND
VOLTAGE (2V/div)
MAX4178/4278-07
IN
10M
FREQUENCY (Hz)
MAX4178 LARGE-SIGNAL
PULSE RESPONSE (CL = 0pF)
MAX4178 SMALL-SIGNAL
PULSE RESPONSE (CL = 0pF)
TIME (10ns/div)
VO = 2Vp-p
10
5.9
4
MAX4178/4278-06
6
6.1
MAX4178/4278-09
7
MAX4178/4278-05
6.2
MAX4178/4278-04
8
GAIN (dB)
1
GAIN (dB)
GAIN (dB)
GAIN (dB)
-2
VO = 2Vp-p
2
-0.1
-1
4
3
MAX4178/4278-02
0.2
MAX4178/4278-01
2
MAX4178
LARGE-SIGNAL GAIN vs. FREQUENCY
MAX4178
GAIN FLATNESS vs. FREQUENCY
MAX4178/4278-03
MAX4178
SMALL-SIGNAL GAIN vs. FREQUENCY
VOLTAGE (100mV/div)
MAX4178/MAX4278
330MHz, Gain of +1/Gain of +2
Closed-Loop Buffers
TIME (10ns/div)
TIME (10ns/div)
_______________________________________________________________________________________
330MHz, Gain of +1/Gain of +2
Closed-Loop Buffers
MAX4178 SMALL-SIGNAL
PULSE RESPONSE (CL = 50pF)
GND
OUT
GND
TIME (10ns/div)
GND
OUT
MAX4178/4278-12
OUT
GND
TIME (20ns/div)
MAX4178 LARGE-SIGNAL
PULSE RESPONSE (CL = 100pF)
MAX4278 SMALL-SIGNAL
PULSE RESPONSE (CL = 50pF)
MAX4178/4278-14
IN
GND
IN
(50mV/
div)
GND
OUT
GND
OUT
(100mV/
div)
GND
VOLTAGE
GND
VOLTAGE (2V/div)
VOLTAGE (100mV/div)
IN
GND
TIME (20ns/div)
MAX4178/4278-13
MAX4178 SMALL-SIGNAL
PULSE RESPONSE (CL = 100pF)
IN
MAX4178/4278-15
GND
IN
VOLTAGE (2V/div)
VOLTAGE
GND
OUT
(2V/div)
MAX4178 LARGE-SIGNAL
PULSE RESPONSE (CL = 50pF)
MAX4178/4278-11
IN
(1V/div)
VOLTAGE (100mV/div)
MAX4178/4278-10
MAX4278 LARGE-SIGNAL
PULSE RESPONSE (CL = 0pF)
TIME (20ns/div)
TIME (20ns/div)
MAX4278 SMALL-SIGNAL
PULSE RESPONSE (CL = 100pF)
MAX4278 LARGE-SIGNAL
PULSE RESPONSE (CL = 100pF)
IN
(1V/div)
IN
(50mV/
div)
GND
OUT
(100mV/
div)
GND
OUT
(2V/div)
GND
IN
(1V/div)
GND
VOLTAGE
VOLTAGE
VOLTAGE
GND
MAX4178/4278-18
MAX4178/4278-16
MAX4278 LARGE-SIGNAL
PULSE RESPONSE (CL = 50pF)
MAX4178/4278-17
TIME (20ns/div)
TIME (20ns/div)
OUT
(2V/div)
GND
TIME (20ns/div)
TIME (20ns/div)
_______________________________________________________________________________________
5
MAX4178/MAX4278
____________________________Typical Operating Characteristics (continued)
(VCC = +5V, VEE = -5V, RL = 100Ω, CL = 0pF, TA = +25°C, unless otherwise noted.)
____________________________Typical Operating Characteristics (continued)
(VCC = +5V, VEE = -5V, RL = 100Ω, CL = 0pF, TA = +25°C, unless otherwise noted.)
MAX4278
DIFFERENTIAL PHASE/GAIN
-0.04
RL = 150Ω
-0.06
IRE
0.002
0.000
-0.002
-0.004
-0.006
-0.008 RL = 150Ω
-0.010
0
100
DIFF PHASE (deg)
DIFF PHASE (deg)
0
-40
IRE
100
0.002
0.000
-0.004
TOTAL HARMONIC DISTORTION
-60
SECOND HARMONIC
THIRD HARMONIC
-80
-0.002
RL = 150Ω
-100
-0.006
100
IRE
-20
MAX4178/4278-21
-0.02
0.02
0.01
0.00
-0.01
-0.02
-0.03
-0.04
-0.05 RL = 150Ω
-0.06
0
MAX4178/4278-20
0.00
DIFF GAIN (%)
MAX4178/4278-19
DIFF GAIN (%)
0.02
MAX4178 HARMONIC DISTORTION
vs. FREQUENCY
DISTORTION (dB)
MAX4178
DIFFERENTIAL PHASE/GAIN
0
1k
100
IRE
10k
100k
1M
10M
100M
FREQUENCY (Hz)
MAX4278 HARMONIC DISTORTION
vs. FREQUENCY
3rd HARMONIC
-80
-90
-60
-70
-80
MAX4278
-90
100k
1M
10M
MAX4178
30k
100k
1M
10M
100M
100k
1M
10M
100M
500M
FREQUENCY (Hz)
FREQUENCY (Hz)
FREQUENCY (Hz)
INPUT OFFSET VOLTAGE (VOS)
vs. TEMPERATURE
QUIESCENT SUPPLY CURRENT (ISY)
vs. TEMPERATURE
INPUT BIAS CURRENT (IB)
vs. TEMPERATURE
200
100
0
-100
-200
-300
12
10
8
6
4
2
0
25
50
75
TEMPERATURE (˚C)
100
125
VIN = 0V
3.0
2.5
2.0
1.5
1.0
0.5
0
-25
3.5
MAX4178/4278-27
MAX4178/4278-26
300
14
QUIESCENT SUPPLY CURRENT (mA)
MAX4178/4278-25
VIN = 0V
6
1
0.1
100M
400
-50
10
MAX4278
-110
10k
100
MAX4178
-100
-100
MAX4178/4278-24
-40
-50
1k
OUTPUT IMPEDANCE (Ω)
-70
-30
INPUT BIAS CURRENT (µA)
DISTORTION (dB)
TOTAL HARMONIC DISTORTION
-60
MAX4178/4278-23
-50
OUTPUT IMPEDANCE
vs. FREQUENCY
-20
POWER-SUPPLY REJECTION (dB)
2nd HARMONIC
POWER-SUPPLY REJECTION
vs. FREQUENCY
MAX4178/4278-22
-40
INPUT OFFSET VOLTAGE (µV)
MAX4178/MAX4278
330MHz, Gain of +1/Gain of +2
Closed-Loop Buffers
-50
-25
0
25
50
75
TEMPERATURE (˚C)
100
125
0
-50
-25
0
25
50
75
TEMPERATURE (˚C)
_______________________________________________________________________________________
100
125
330MHz, Gain of +1/Gain of +2
Closed-Loop Buffers
3.5
RL = 100Ω
RL = 50Ω
3.0
MAX4178/4278-29
4.5
4.0
INPUT VOLTAGE RANGE (±V)
4.0
MAX4178/4278-28
RL =
INPUT VOLTAGE RANGE
vs. TEMPERATURE
8
OUTPUT VOLTAGE SWING (±V)
OUTPUT VOLTAGE SWING
vs. TEMPERATURE
3.5
MAX4178
3.0
2.5
2.0
MAX4278
1.5
2.5
-50
1.0
-25
0
25
50
75
100
125
TEMPERATURE (˚C)
NAME
-25
0
25
50
75
100
125
TEMPERATURE (˚C)
_____________________Pin Description
PIN
-50
FUNCTION
SO/µMAX/DIP
SOT23
1, 5, 8
—
N.C.
No Connection
2
4
GND
Ground
3
3
IN
4
2
VEE
6
1
OUT
7
5
VCC
Input
Negative Power Supply.
Connect to -5V.
Output
Positive Power Supply.
Connect to +5V.
_______________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 HighPerformance Video Distribution Amplifier in the
Applications Information section.
_______________________________________________________________________________________
7
MAX4178/MAX4278
____________________________Typical Operating Characteristics (continued)
(VCC = +5V, VEE = -5V, RL = 100Ω, CL = 0pF, TA = +25°C, unless otherwise noted.)
MAX4178/MAX4278
330MHz, Gain of +1/Gain of +2
Closed-Loop Buffers
__________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.
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 RISO 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 RISO 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.
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
RISO
VIN
MAX4178
MAX4278
VOUT
CL
Figure 1. Capacitive-Load Driving Circuit
8
_______________________________________________________________________________________
RL
330MHz, Gain of +1/Gain of +2
Closed-Loop Buffers
CL = 100pF
CL = 47pF
CL = 22pF
10
26
21
CL = 100pF
CL = 47pF
CL = 22pF
16
5
11
GAIN (dB)
GAIN (dB)
RISO = 0Ω
0
-5
-10
-15
6
1
-4
-9
CL = 0pF
-20
CL = 0pF
-14
-25
-19
-30
-24
1M
10M
100M
1G
1M
10M
FREQUENCY (Hz)
AND ISOLATION RESISTOR
CL = 0pF
0
8
MAX4178/4278-3a
CL = 22pF
RISO = 20Ω
7
CL = 22pF
RISO = 20Ω
CL = 0pF
6
-1
5
CL = 47pF
-2
GAIN (dB)
GAIN (dB)
1G
Figure 2b. MAX4278 Small-Signal Gain vs. Frequency with
Capacitive Load
AND ISOLATION RESISTOR
2
100M
FREQUENCY (Hz)
Figure 2a. MAX4178 Small-Signal Gain vs. Frequency with
Capacitive Load
1
MAX4178/4278-2b
RISO = 0Ω
MAX4178/4278-3b
15
MAX4178/4278-2a
20
MAX4178/MAX4278
MAX4278 SMALL SIGNAL GAIN vs.
FREQUENCY WITH CAPACITIVE LOAD
FREQUENCY WITH CAPACITIVE LOAD
CL = 100pF
-3
-4
-5
CL = 47pF
4
CL = 100pF
3
2
1
-6
0
-7
-1
-8
-2
1M
10M
100M
1G
FREQUENCY (Hz)
Figure 3a. MAX4178 Small-Signal Gain vs. Frequency with
Capacitive Load and Isolation Resistor (RISO)
1M
10M
100M
1G
FREQUENCY (Hz)
Figure 3b. MAX4278 Small-Signal Gain vs. Frequency with
Capacitive Load and Isolation Resistor (RISO)
_______________________________________________________________________________________
9
MAX4178/MAX4278
330MHz, Gain of +1/Gain of +2
Closed-Loop Buffers
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.
_Ordering Information (continued)
TEMP. RANGE
PINPACKAGE
MAX4278EPA
-40°C to +85°C
8 Plastic DIP
MAX4278ESA
MAX4278EUA
MAX4278EUK-T
MAX4278MJA
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
8 SO
8 µMAX
5 SOT23
8 CERDIP
PART
VIDEO IN
MAX4178
MAX4278
FLASH ADC
(MAX100/MAX101)
TRANSISTOR COUNT: 175
SUBSTRATE CONNECTED TO VEE
75Ω
75Ω
OUT1
MAX4278
75Ω
75Ω
75Ω
OUT2
75Ω
75Ω
75Ω
OUTN
75Ω
Figure 5. High-Performance Video Distribution Amplifier
10
–
–
–
ABYY
–
___________________Chip Information
Figure 4. Preamp for Video Digitizer
VIDEO IN
SOT
TOP MARK
______________________________________________________________________________________
330MHz, Gain of +1/Gain of +2
Closed-Loop Buffers
PDIPN.EPS
SOICN.EPS
______________________________________________________________________________________
11
MAX4178/MAX4278
________________________________________________________Package Information
8LUMAXD.EPS
___________________________________________Package Information (continued)
SOT5L.EPS
MAX4178/MAX4278
330MHz, Gain of +1/Gain of +2
Closed-Loop Buffers
12
______________________________________________________________________________________