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19-0016; Rev 1; 1/95
140MHz, 2-Channel
Video Multiplexer/Amplifier
_______________General Description
The MAX442 combines a 140MHz video amplifier with a
high-speed, 2-channel multiplexer in an 8-pin package.
With its 36ns switching time and low differential gain
(0.07%) and phase (0.09°) errors, it is ideal for broad-
cast-quality video applications. The device is designed
to drive both 50Ω and 75Ω cables, and can directly
drive a 75Ω load to ±3V.
The MAX442 video amplifier is compensated for unity-
gain stability, and features a 140MHz bandwidth and a
250V/µs slew rate. The multiplexer’s low input capaci-
tance (4pF with the channel on or off) maximizes high-
speed performance, and a ground pin separating the
two input channels minimizes crosstalk and simplifies
board layout.
The MAX442 operates from ±5V supplies and typically
consumes 300mW. For applications that require more
input channels, see the data sheets for the MAX440 8-
channel mux/amp and the MAX441 4-channel mux/amp.
____________________________Features
o
140MHz Unity-Gain Bandwidth
o
250V/µs Slew Rate
o
0.07%/0.09° Differential Gain/Phase Error
o
36ns Channel Switch Time
o
No External Compensation Components
o
8-Pin DIP and SO Packages
o
Directly Drives 50Ω and 75Ω Cables
MAX442
______________Ordering Information
PART
MAX442CPA
MAX442CSA
MAX442C/D
MAX442EPA
MAX442ESA
TEMP. RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
8 Plastic DIP
8 SO
Dice*
8 Plastic DIP
8 SO
________________________Applications
Broadcast-Quality Video-Signal Multiplexing
Coaxial-Cable Drivers
Video Editing
Video Security Systems
Medical Imaging
High-Speed Signal Processing
*Dice are specified at T
A
= +25°C, DC parameters only.
__________Typical Operating Circuit
+5V
__________________Pin Configuration
TOP VIEW
0.1µF
V+
MAX442
V
OUT
VIDEO
SIGNALS
IN
IN0
270Ω
IN-
270Ω
75Ω
75Ω
75Ω
CABLE
VIDEO
OUTPUT
IN0 1
GND 2
IN1 3
V- 4
8
7
A0
V+
V
OUT
IN-
IN1
A0
GND
V-
0.1µF
MAX442
6
5
DIP/SO
CHANNEL
SELECT
-5V
________________________________________________________________
Maxim Integrated Products
1
Call toll free 1-800-998-8800 for free samples or literature.
140MHz, 2-Channel
Video Multiplexer/Amplifier
MAX442
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (V+ to V-).......................................................12V
Analog Input Voltage ............................(V+ + 0.3V) to (V- - 0.3V)
Digital Input Voltage .....................................-0.3V to (V+ + 0.3V)
Short-Circuit Current Duration ........................................1 minute
Input Current to Any Pin, Power On or Off........................±50mA
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
Operating Temperature Ranges
MAX442C_A........................................................0°C to +70°C
MAX442E_A .....................................................-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.
ELECTRICAL CHARACTERISTICS
(V+ = 5V, V- = -5V, R
L
= 150Ω, T
A
= T
MIN
to T
MAX
, unless otherwise noted.)
PARAMETER
DC PERFORMANCE
Input Voltage Range
Input Offset Voltage
(All Channels)
Offset Matching
(V
OS0
–V
OS1
)
Input Bias Current
(Channel On)
Input Leakage Current
(Channel Off)
Input Resistance
(Channel On) (Note 1)
Input Capacitance
DC Output Resistance
Open-Loop Voltage Gain
Common-Mode Rejection Ratio
Power-Supply Rejection Ratio
Output Voltage Swing
I
B
I
LKG
R
IN
C
IN
R
OUT
A
VOL
CMRR
PSRR
V
OUT
V
IN
T
A
= +25°C
V
OS
MAX442C
MAX442E
T
A
= +25°C
T
A
= T
MIN
to T
MAX
V
IN
= 0V
V
IN
= 0V
-2V
≤
V
CM
≤
2V
Channel on or off
A
V
= 0dB
A
V
= 6dB
R
L
= 75Ω,
-2V
≤
V
OUT
≤
+2V
-2V
≤
V
IN
≤
+2V
±4.75V to ±5.25V
R
L
= 75Ω
T
A
= +25°C
T
A
= T
MIN
to T
MAX
T
A
= +25°C
T
A
= T
MIN
to T
MAX
T
A
= +25°C
T
A
= T
MIN
to T
MAX
T
A
= +25°C
T
A
= T
MIN
to T
MAX
50
46
46
46
54
54
±2.5
±2.0
±3.0
80
50
T
A
= +25°C
T
A
= T
MIN
to T
MAX
T
A
= +25°C
T
A
= T
MIN
to T
MAX
T
A
= +25°C
T
A
= T
MIN
to T
MAX
0.5
0.2
4
25
50
60
2.0
±0.5
±0.6
±1
-2
±1.5
2
±7.0
±10
±12
±2.5
±5.0
±2
±5
±50
±1
mV
µA
nA
µA
MΩ
pF
mΩ
dB
dB
dB
V
mV
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
2
_______________________________________________________________________________________
140MHz, 2-Channel
Video Multiplexer/Amplifier
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 5V, V- = -5V, R
L
= 150Ω, T
A
= T
MIN
to T
MAX
, unless otherwise noted.)
PARAMETER
DYNAMIC PERFORMANCE
-3dB Bandwidth
Slew Rate
Differential Phase Error
Differential Gain Error
Settling Time
Crosstalk
Input Noise-Voltage Density
POWER REQUIREMENTS
Operating Supply-Voltage Range
Positive Supply Current
V
S
T
A
= +25°C
I
CC
V
IN
= 0V
MAX442C
MAX442E
T
A
= +25°C
Negative Supply Current
SWITCHING CHARACTERISTICS
Logic Low Voltage
Logic High Voltage
Address Propagation Delay
Channel Switching Time
V
IL
V
IH
t
APD
t
SW
Figure 7
Figure 7 (Note 2)
2.4
24
36
0.8
V
V
ns
ns
I
EE
V
IN
= 0V
MAX442C
MAX442E
±4.75
25
22
19
23
20
17
28
30
±5.25
35
38
41
35
38
41
mA
mA
V
BW
SR1
DP
DG
t
s
X
TALK
e
n
Figure 1
Figure 1
To 0.1% of final value,
A
V
= 0dB, R
L
= 150Ω, 2V step input
f = 10MHz, R
S
= 75Ω, A
V
= 0dB, Figure 6
f = 10kHz
A
V
= 0dB, R
L
= 100Ω
140
250
0.09
0.07
50
76
12
MHz
V/µs
degrees
%
ns
dB
nV/
√
Hz
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX442
Note 1:
Incremental resistance for a common-mode voltage between ±2V.
Note 2:
Channel Switching Time specified between two grounded input channels; does not include signal rise/fall times for switch-
ing between channels with different input voltages.
__________________________________________Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
OPEN-LOOP GAIN AND PHASE
vs. FREQUENCY
80
70
OPEN-LOOP GAIN (dB)
60
50
40
30
20
10
0
-10
-20
0.001
0.1
10
PHASE
GAIN
135
90
CLOSED-LOOP GAIN (dB)
PHASE SHIFT (Degrees)
45
0
-45
-90
-135
-180
-225
-270
-315
1000
30
25
20
15
10
5
0
-5
-10
-15
-20
0.1
1
10
100
1000
FREQUENCY (MHz)
0.01
10k
100k
1M
FREQUENCY (Hz)
10M
100M
A
VCL
= 20dB
A
VCL
= 6dB
A
VCL
= 0dB
CLOSED-LOOP GAIN
vs. FREQUENCY
MAX442-02
UNITY-GAIN OUTPUT IMPEDANCE
vs. FREQUENCY
MAX442-03
100
OUTPUT IMPEDANCE (Ω)
10
1
0.1
FREQUENCY (MHz)
_______________________________________________________________________________________
3
140MHz, 2-Channel
Video Multiplexer/Amplifier
MAX442
____________________________Typical Operating Characteristics (continued)
(T
A
= +25°C, unless otherwise noted.)
VOLTAGE-NOISE DENSITY
vs. FREQUENCY
MAX442-04
CROSSTALK
vs. FREQUENCY
MAX442-05
OUTPUT VOLTAGE SWING
vs. LOAD RESISTANCE
4
3
OUTPUT VOLTAGE (V)
2
1
0
-1
-2
-3
-4
MAX442-06
1000
VOLTAGE-NOISE DENSITY (nV/√Hz)
0
-20
CROSSTALK (dB)
5
100
-40
-60
-80
-100
10
1
1
10
100
1k
10k
100k
FREQUENCY (Hz)
-120
1
10
100
1000
FREQUENCY (MHz)
-5
10
100
1k
10k
LOAD RESISTANCE (Ω)
SUPPLY CURRENT
vs. TEMPERATURE
MAX442-07
INPUT OFFSET VOLTAGE
vs. TEMPERATURE
MAX442-08
INPUT BIAS CURRENT
vs. TEMPERATURE
0.9
INPUT BIAS CURRENT (µA)
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
V
CM
= 0V
MAX442-09
40
30
SUPPLY CURRENT (mA)
20
10
0
-10
-20
-30
-40
-40 -20
0
20
40
60
80
I
EE
I
CC
5
4
INPUT OFFSET VOLTAGE (mV)
3
2
1
0
-1
-2
-3
-4
-5
1.0
100
-40 -20
0
20
40
60
80
100
-40 -20
0
20
40
60
80
100
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
OPEN-LOOP VOLTAGE GAIN
vs. TEMPERATURE
MAX442-10
COMMON-MODE REJECTION RATIO
vs. TEMPERATURE
DIFFERENTIAL INPUT OFFSET VOLTAGE (mV)
COMMON-MODE REJECTION RATIO (dB)
70
60
50
40
30
20
10
0
-40 -20
0
20
40
60
80
100
MAX442-11
DIFFERENTIAL INPUT OFFSET VOLTAGE
vs. TEMPERATURE
MAX442-12
80
OPEN-LOOP VOLTAGE GAIN (dB)
70
60
50
40
30
20
10
0
-40 -20
0
20
40
60
80
80
3
2
1
0
-1
-2
-3
-40 -20
0
20
40
60
80
100
100
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
4
_______________________________________________________________________________________
140MHz, 2-Channel
Video Multiplexer/Amplifier
_____________________Pin Description
PIN
1
2
3
4
5
6
7
8
NAME
IN0
GND
IN1
V-
IN-
V
OUT
V+
A0
FUNCTION
Analog Input, channel 0
Ground
Analog Input, channel 1
Negative Power Supply, -5V
Amplifier Inverting Input
Amplifier Output
Positive Power Supply, +5V
Channel Address Input:
A0 = logic 0 selects channel 0,
A0 = logic 1 selects channel 1
__________Applications Information
The MAX442’s bipolar construction results in a typical
channel input capacitance of only 4pF, whether the
channel is on or off. As with all ICs, the mux’s input
capacitance forms a single-pole RC lowpass filter with
the signal source’s output impedance. This filter can
limit the system’s signal bandwidth if the RC product
becomes too large. However, the MAX442’s low chan-
nel input capacitance allows full AC performance of the
amplifier, even with source impedances as great as
250Ω—a significant improvement over common mux or
switch alternatives.
Feedback resistors should be limited to no more than
500Ω to ensure that the RC time constant formed by the
resistors, the circuit board’s capacitance, and the
capacitance of the amplifier input pins does not limit
the system’s high-speed performance.
To prevent oscillation and unwanted signal coupling,
minimize trace area at the circuit’s critical high-imped-
ance nodes, especially the amplifier summing junction
(the amplifier’s inverting input). Surround these critical
nodes with a ground trace, and include ground traces
between all signal traces to minimize parasitic coupling
that can degrade crosstalk and/or amplifier stability.
Keep signal paths as short as possible to minimize
inductance, and keep all input channel traces at equal
lengths to maintain the phase relationship between the
input channels.
Bypass all power-supply pins directly to the ground
plane with 0.1µF ceramic capacitors, placed as close
to the supply pins as possible. For high-current loads,
it may be necessary to include 1µF tantalum or alu-
minum-electrolytic capacitors in parallel with the 0.1µF
ceramic bypass capacitors. Keep capacitor lead
lengths as short as possible to minimize series induc-
tance; surface-mount (chip) capacitors are ideal for this
application.
MAX442
Differential Gain and Phase Errors
In color video applications, lowest differential gain and
phase errors are critical for an IC, because they cause
changes in contrast and color of the displayed picture.
Typically, the MAX442’s multiplexer/amplifier combina-
tion has a differential gain and phase error of only
0.07% and 0.09°, respectively. This low differential
gain and phase error makes the MAX442 ideal for use
in broadcast-quality color video systems.
Coaxial-Cable Drivers
High-speed performance and excellent output current
capability make the MAX442 ideal for driving 50Ω or
75Ω coaxial cables. The MAX442 will drive 50Ω and
75Ω coaxial cables to ±3V.
75Ω
CABLE
75Ω
75Ω
75Ω
CABLE
Power-Supply Bypassing
and Board Layout
Realizing the full AC performance of high-speed ampli-
fiers requires careful attention to power-supply bypass-
ing and board layout. Use a low-impedance ground
plane with the MAX442. With multilayer boards, the
ground plane should be located on the PC board’s
component side to minimize impedance between the
components and the ground plane. For single-layer
boards, components should be mounted on the board’s
copper side and the ground plane should include the
entire portion of the board that is not dedicated to a
specific signal trace.
MAX442
75Ω
470Ω
SOURCE:
TEKTRONIX
1910 DIGITAL GENERATOR
470Ω
75Ω
CABLE
75Ω
MEASUREMENT:
TEKTRONIX
VM700 VIDEO
MEASUREMENT SET
Figure 1. Differential Gain and Phase Error Test Circuit
_______________________________________________________________________________________
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