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19-0373; Rev 1; 12/98
ANUAL N KIT M LUATIO ATA SHEET EVA WS D FOLLO
375MHz Quad Closed-Loop Video Buffers, AV = +1 and +2
____________________________Features
o MAX496 Fixed Gain: +1V/V MAX497 Fixed Gain: +2V/V o High Speed: Small-Signal -3dB Bandwidth: 375MHz (MAX496) 275MHz (MAX497) Full-Power -3dB Bandwidth: 230MHz (MAX496) 215MHz (MAX497) o 0.1dB Gain Flatness: 65MHz (MAX496) 120MHz (MAX497) o 1600V/s Slew Rate (MAX496) 1500V/s Slew Rate (MAX497) o Fast Settling Time: 12ns to 0.1% o Lowest Differential Phase/Gain Error: 0.01/0.01% o 2pF Input Capacitance o 5.6nV/Hz Input-Referred Voltage Noise o Low Distortion: 64dBc (f = 10MHz) o Directly Drives 50 or 75 Back-Terminated Cables o High ESD Protection: 5000V o Output Short-Circuit Protected
________________General Description
The MAX496 and MAX497 are quad, closed-loop, 5V video buffers that feature extremely high bandwidth and slew rate for both component video (RGB or YUV) and composite video (NTSC, PAL, SECAM). The MAX496 is a unity-gain (0dB) buffer with a 375MHz -3dB bandwidth and a 1600V/s slew rate. The MAX497 gain of +2 (6dB) buffer, optimized for driving back-terminated coaxial cable, features a 275MHz -3dB bandwidth and a 1500V/s slew rate. The MAX496/MAX497 are not slewrate limited, thus providing a high full-power bandwidth of 230MHz and 215MHz, respectively. The MAX496/MAX497 incorporate a unique two-stage architecture that combines the low offset and noise benefits of voltage feedback with the high bandwidth and slew-rate advantages of current-mode-feedback.
MAX496/MAX497
________________________Applications
Computer Workstations Surveillance Video Broadcast and High-Definition TV Systems Multimedia Products Medical Imaging High-Speed Signal Processing Video Switching and Routing
_______________Ordering Information
PART MAX496CPE TEMP. RANGE 0C to +70C PIN-PACKAGE 16 Plastic DIP
_______________Frequency Response
MAX497 SMALL-SIGNAL GAIN vs. FREQUENCY
8 7 6 GAIN (dB) 5 4 3 2 1 0 -1 1M 10M 100M 1G FREQUENCY (Hz)
MAX496/97-A
MAX496CSE 0C to +70C 16 Narrow SO MAX496C/D 0C to +70C Dice* MAX497CPE 0C to +70C 16 Plastic DIP MAX497CSE 0C to +70C 16 Narrow SO MAX497C/D 0C to +70C Dice* * Dice are specified at TA = +25C, DC parameters only.
___________________Pin Configuration
TOP VIEW
GND 1 IN0 2 GND 3 IN1 4 GND 5 IN2 6 GND 7 IN3 8 16 OUT0 15 VCC 14 OUT1
9
MAX496 MAX497
13 VEE 12 OUT2 11 VEE 10 OUT3 9 VCC
DIP/SO 1
________________________________________________________________ Maxim Integrated Products
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 1-800-835-8769.
375MHz Quad Closed-Loop Video Buffers, AV = +1 and +2 MAX496/MAX497
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (VCC to VEE) ................................................. 12V Voltage on Any Input Pin to GND ....(VCC + 0.3V) to (VEE - 0.3V) Output Short-Circuit Current Duration ...............................60sec Continuous Power Dissipation (TA = +70C) Plastic DIP (derate 10.53mW/C above +70C) ..........842mW Narrow SO (derate 8.70mW/C above +70C) ............696mW Operating Temperature Range...............................0C to +70C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10sec) .............................+300C
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, VIN = 0V, RL = 150, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER Input Voltage Range Input Offset Voltage Input Offset Voltage Drift Input Bias Current Input Resistance Input Capacitance SYMBOL VIN VOS TCVOS IB RIN CIN MAX496 (Note 1) Voltage Gain AV MAX497 (Note 2) Positive Power-Supply Rejection Ratio (Change in VOS) Negative Power-Supply Rejection Ratio (Change in VOS) Gain Linearity Positive Quiescent Supply Current (Total) Negative Quiescent Supply Current (Total) Operating Supply Voltage Range Output Voltage Swing Output Resistance Output Impedance Short-Circuit Output Current PSRR+ PSRRAVLIN ISY+ ISYVS VOUT ROUT ZOUT ISC RL = 150 RL = 50 DC f = 10MHz Short to ground or either supply voltage RL = 150 RL = 50 RL = 150 RL = 50 0.988 0.983 1.975 1.965 55 60 74 78 0.01 31 32 4.50 2.8 2.5 3.7 3.3 0.1 1.5 170 36 45 37 45 5.50 MAX496 MAX497 VOUT = 0V VOUT = 0V VOUT = 0V MAX496: -2V VIN +2V, MAX497: -1V VIN +1V 0.5 CONDITIONS MIN 2.8 1.4 TYP 3.2 1.6 1 -10 1 1.2 2 1.00 1.00 2.01 2.01 dB dB % mA mA V V mA V/V 5 3 MAX UNITS V mV V/C A M pF
VCC = 4.5V to 5.5V, VEE = -5.0V VEE = 4.5V to 5.5V, VCC = 5.0V AVCL = +2, VOUT = 1mV to 2V TA = +25C TA = TMIN to TMAX TA = +25C TA = TMIN to TMAX
2
_______________________________________________________________________________________
375MHz Quad Closed-Loop Video Buffers, AV = +1 and +2
AC ELECTRICAL CHARACTERISTICS
(VCC = +5V, VEE = -5V, VIN = 0V, RL = 100, TA = +25C.) PARAMETER Small-Signal -3dB Bandwidth Small-Signal -3dB Bandwidth BW-3dB SYMBOL MAX496CSE MAX496CPE MAX497CSE MAX497CPE Full-Power Bandwidth Slew Rate Settling Time Differential Gain Error Differential Phase Error Input Noise Voltage Density Input Noise Current Density FPBW SR ts DG DP VOUT = 2V MAX496 MAX497 CONDITIONS MIN TYP 375 375 275 275 230 215 1600 1500 12 0.01 0.01 5.6 2 MAX496CPE Gain Flatness 0.1dB MAX496CSE MAX497CPE MAX497CSE Adjacent Channel Crosstalk All-Hostile Crosstalk Total Harmonic Distortion Spurious-Free Dynamic Range THD SFDR (Note 4) (Note 4) fC = 10MHz, VOUT = 2Vp-p fC = 5MHz MAX496 MAX497 MAX496 MAX497 MAX496 MAX497 MAX496 MAX497 80 80 100 120 78 72 72 65 -64 -58 58 60 dB dB dBc dBc MHz MHz V/s ns % degrees nVHz pAHz MHz MAX UNITS
MAX496/MAX497
VOUT = 4V step, MAX496 VOUT = 4V step, MAX497 0.1% (VOUT = 2V step) f = 3.58MHz (Note 3) f = 3.58MHz (Note 3) f = 10MHz f = 10MHz
Note 1: Voltage Gain = (VOUT - VOS) / VIN, measured at VIN = 1V. Note 2: Voltage Gain = (VOUT - VOS) / VIN, measured at VIN = 2V. Note 3: Input test signal is a 3.58MHz sine wave of amplitude 40 IRE superimposed on a linear ramp (0 IRE to 100 IRE). RL = 150, see Figure 2. Note 4: Input of channel under test grounded through 75. Adjacent channel driven at f = 10MHz (Figure 4a). For All-Hostile Crosstalk, all inputs are driven except the channel under test (Figure 4b).
_______________________________________________________________________________________
3
375MHz Quad Closed-Loop Video Buffers, AV = +1 and +2 MAX496/MAX497
__________________________________________Typical Operating Characteristics
(VCC = +5V, VEE = -5V, RL = 100, TA = +25C, unless otherwise noted.)
MAX496 SMALL-SIGNAL GAIN vs. FREQUENCY
MAX496/97-01
MAX496 GAIN FLATNESS vs. FREQUENCY
MAX496/97-02
MAX496 LARGE-SIGNAL GAIN vs. FREQUENCY
1 0 -1 GAIN (dB) -2 -3 -4 -5 -6 -7 -8
MAX496/97-03
2 1 0 -1 GAIN (dB) -2 -3 -4 -5 -6 -7 -8 1M 10M 100M
0.2 0.1 0 -0.1 GAIN (dB) -0.2 -0.3 -0.4 -0.5 -0.6 -0.7 -0.8
2
1G
1M
10M
100M
1G
1M
10M
100M
1G
FREQUENCY (Hz)
FREQUENCY (Hz)
FREQUENCY (Hz)
MAX497 SMALL-SIGNAL GAIN vs. FREQUENCY
MAX496/97-04
MAX497 GAIN FLATNESS vs. FREQUENCY
6.1 6.0 5.9 GAIN (dB) GAIN (dB) 5.8 5.7 5.6 5.5 5.4 5.3 5.2 DIP SO
MAX496/97-05
MAX497 LARGE-SIGNAL GAIN vs. FREQUENCY
7 6 5 4 3 2 1 0 -1 -2
MAX496/97-06
9 8 7 6 GAIN (dB) 5 4 3 2 1 0 -1 1M 10M 100M
6.2
8
1G
1M
10M
100M
1G
1M
10M
100M
1G
FREQUENCY (Hz)
FREQUENCY (Hz)
FREQUENCY (Hz)
MAX496 SMALL-SIGNAL GAIN vs. FREQUENCY DRIVING A 50 LOAD
MAX496/97-07
MAX497 SMALL-SIGNAL GAIN vs. FREQUENCY DRIVING A 50 LOAD
MAX496/97-08
TOTAL HARMONIC DISTORTION (THD) vs. FREQUENCY
-10 -20 DISTORTION (dB) -30 MAX497 -40 -50 -60 -70 -80 -90 MAX496 VOUT = 2Vp-p
MAX496/97-09
2 1 0 -1 GAIN (dB) -2 -3 -4 -5 -6 -7 -8 1M 10M 100M
8 7 6 5 GAIN (dB) 4 3 2 1 0 -1 -2
0
1G
1M
10M
100M
1G
10k
100k
1M
10M
100M
FREQUENCY (Hz)
FREQUENCY (Hz)
FREQUENCY (Hz)
4
_______________________________________________________________________________________
375MHz Quad Closed-Loop Video Buffers, AV = +1 and +2
_____________________________Typical Operating Characteristics (continued)
(VCC = +5V, VEE = -5V, RL = 100, TA = +25C, unless otherwise noted.)
MAX496/MAX497
MAX496 CROSSTALK vs. FREQUENCY
MAX496/97-10
MAX497 CROSSTALK vs. FREQUENCY
MAX496/97-11
POWER-SUPPLY REJECTION (PSR) vs. FREQUENCY
POWER-SUPPLY REJECTION (dB) -20 -30 MAX497 -40 -50 -60 -70 -80 -90 -100 20k 100k MAX496 1M 10M 100M
MAX496/97-12
-10 -20 -30 CROSSTALK (dB) ALL-HOSTILE
0 -10 -20 CROSSTALK (dB) -30 -40 -50 -60 -70 -80 -90 -100 ALL-HOSTILE ADJACENT CHANNEL
-10
-40 -50 -60 -70 -80 -90 -100 -110 1 10 FREQUENCY (MHz) 100 200 ADJACENT CHANNEL
1M
10M
100M
1G
FREQUENCY (Hz)
FREQUENCY (Hz)
MAX496 GAIN MATCH vs. FREQUENCY
MAX496/97-13a
MAX497 GAIN MATCH vs. FREQUENCY
0.4 0.3 GAIN MATCH (dB) 0.2 0.1 0 -0.1 -0.2 -0.3 -0.4 -0.5 CH 3-CH 0 CH 3-CH 2 CH 2-CH 1 1M 10M 100M 1G CH 2-CH 0 CH 1-CH 0 GAIN (V/V) CH 3-CH 1
MAX496/97-13b
MAX496 GAIN vs. TEMPERATURE
0.999 0.998 0.997 0.996 0.995 0.994 0.993 0.992 0.991 0.990 -40 -20 0 20 40 60 80 100 VIN = -1.0V VIN = -1.0V
MAX496/97-14
0.3 0.2 0.1 GAIN MATCH (dB) 0.0 -0.1 -0.2 -0.3 -0.4 -0.5 -0.6 -0.7 1M 10M 100M CH 3-CH 2 CH 1-CH 0 CH 3-CH 0 CH 2-CH 0 CH 3-CH 1 CH 2-CH 1
0.5
1.000
1G
FREQUENCY (Hz)
FREQUENCY (Hz)
TEMPERATURE (C)
MAX497 GAIN vs. TEMPERATURE
MAX496/97-15
INPUT OFFSET VOLTAGE vs. TEMPERATURE
MAX496/97-16
SUPPLY CURRENT vs. TEMPERATURE
38 SUPPLY CURRENT (mA) 36 34 32 30 28 26 24 22 20 ICC IEE RL = NO LOAD
MAX496/97-17
2.05 2.04 2.03 2.02 GAIN (V/V) 2.01 2.00 1.99 1.98 1.97 1.96 1.95 -40 -20 0 20 40 60 80 VIN = -1.0V VIN = +1.0V
0.30 0.20 OFFSET VOLTAGE (mV) 0.10 0 -0.10 -0.20 -0.30
40
100
-40
-20
0
20
40
60
80
100
-10
0
10
20
30
40
50
60 70 80
TEMPERATURE (C)
TEMPERATURE (C)
TEMPERATURE (C)
_______________________________________________________________________________________
5
375MHz Quad Closed-Loop Video Buffers, AV = +1 and +2 MAX496/MAX497
_____________________________Typical Operating Characteristics (continued)
(VCC = +5V, VEE = -5V, RL = 100, TA = +25C, unless otherwise noted.)
MAX496 SMALL-SIGNAL PULSE RESPONSE
MAX496/97-18
MAX497 SMALL-SIGNAL PULSE RESPONSE
MAX496/97-19
0.05 IN VOLTAGE (V) -0.05
to 0.50 VOLTAGE (V) TIME (10ns/div) IN -0.50 to 0.10 OUT -0.10
0.05 OUT -0.05
TIME (10ns/div)
MAX496 LARGE-SIGNAL PULSE RESPONSE
MAX496/97-20
MAX497 LARGE-SIGNAL PULSE RESPONSE
1.0 IN VOLTAGE (V) -1.0 2.0 OUT -2.0
MAX496/97-21
1.0 IN VOLTAGE (V) -1.0
1.0 OUT -1.0 TIME (10ns/div)
TIME (10ns/div)
6
_______________________________________________________________________________________
375MHz Quad Closed-Loop Video Buffers, AV = +1 and +2
_____________________________Typical Operating Characteristics (continued)
(VCC = +5V, VEE = -5V, RL = 100, TA = +25C, unless otherwise noted.)
MAX496/MAX497
MAX496 SMALL-SIGNAL PULSE RESPONSE (CL = 47pF
MAX496/97-22
MAX497 SMALL-SIGNAL PULSE RESPONSE (CL = 47pF)
0.50 IN VOLTAGE (V) -0.50 0.10 OUT -0.10
MAX496/97-23
0.05 IN VOLTAGE (V) -0.05
0.05 OUT -0.05
10ns/div
10ns/div
MAX496 LARGE-SIGNAL PULSE RESPONSE (CL = 47pF)
1.0 IN VOLTAGE (V) -1.0 VOLTAGE (V)
MAX496/97-24
MAX497 LARGE-SIGNAL PULSE RESPONSE (CL = 47pF)
1.0 IN -1.0 2.0 OUT -2.0
MAX496/97-25
1.0 OUT -1.0
10ns/div
10ns/div
_______________________________________________________________________________________
7
375MHz Quad Closed-Loop Video Buffers, AV = +1 and +2 MAX496/MAX497
_____________________Pin Description
PIN 1, 3, 5, 7 2 4 6 8 9, 15 10 11, 13 12 14 16 NAME GND IN0 IN1 IN2 IN3 VCC OUT3 VEE OUT2 OUT1 OUT0 FUNCTION Ground. All ground pins are internally connected. Connect all ground pins externally to minimize the ground impedance. Channel 0 Input Channel 1 Input Channel 2 Input Channel 3 Input Positive Power Supply. Connect to +5V. VCC pins are internally connected. Connect both pins to +5V externally to minimize the supply impedance. Channel 3 Output Negative power supply. Connect to -5V. VEE pins are internally connected. Connect both pins to -5V externally to minimize the supply impedance. Channel 2 Output Channel 1 Output Channel 0 Output
_______________Detailed Description
The MAX496/MAX497 are quad, high-speed, closed-loop voltage-feedback video amplifiers with fixed gain settings of +1 and +2, respectively (Figure 1). These amplifiers use a unique two-stage voltage-feedback architecture that combines the benefits of conventional voltage-feedback and current-mode-feedback topologies. They achieve wide bandwidths and high slew rates while maintaining precision. A resistively loaded first stage provides low input-referred noise even with low supply currents of 8mA per amplifier. The above features, along with the ability to drive 50 or 75 back-terminated cables to 2.8V and low differential phase and gain errors, make these amplifiers ideal for the most demanding component and composite video applications.
__________Applications Information
The feedback elements of the MAX496/MAX497 are included internally in the device to set the closed-loop gain to AV = +1 and AV = +2, respectively. Closing the loop internally on the chip minimizes problems associated with the board and package parasitics influencing the amplifier's frequency response.
VCC +5V 10F
0.10F 0.10F 9 15 11 13 0.10F
0.10F 10F
VEE
-5V
75 RED
75 CABLE
2 75
IN0
OUT0
16
75
75 CABLE
75
MAX496* MAX497*
75 GREEN 75 75 CABLE 4 IN1 AV = * OUT1 14 75 75 CABLE
75
75 BLUE
75 CABLE
6 75
IN2
AV = *
OUT2
12
75
75 CABLE
75
75 SYNC
75 CABLE
8 75
IN3
AV = *
OUT3
10
75
75 CABLE
75 GND
*AV = +1 (MAX496) *AV = +2 (MAX497)
3
5
7
Figure 1. Typical Operating Circuit
8
_______________________________________________________________________________________
375MHz Quad Closed-Loop Video Buffers, AV = +1 and +2 MAX496/MAX497
a)
75 CABLE
75 75 CABLE DUT SOURCE: TEKTRONIX 1910 DIGITAL GENERATOR 75 75 MEASUREMENT: TEKTRONIX VM700 VIDEO MEASUREMENT SET
MAX497
75
75 CABLE
b)
75 75 CABLE DUT 75 150
MAX496
Figure 2. Differential Phase and Gain Error Test Circuits: a) MAX497, Gain of +2 Amplifier; b) MAX496 Unity-Gain Amplifier
Power Dissipation
The maximum output current of the MAX496/MAX497 is limited by the packages maximum allowable power dissipation. The maximum junction temperature should not exceed +150C. The power dissipation increases with load, and this increase can be approximated by the following: For VOUT > 0V: |VCC - VOUT| ILOAD OR For VOUT < 0V: |VEE - VOUT| ILOAD. These devices can drive 100 loads connected to each of the outputs over the entire rated output swing and temperature range. When driving 50 loads with each of the four outputs simultaneously, the output swing must be limited to 1.25V at TA = +70C. While the output is short-circuit protected to 170mA, this does not necessarily guarantee that, under all conditions, the maximum junction temperature will not be exceeded. Do not exceed the derating values given in the absolute maximum ratings.
MAX496/MAX497
IN0
75 75 75 75 75 75 75 75
OUT1
75
OUT2
OUT3
OUT4
Figure 3. One-to-Four Distribution Amplifier
_______________________________________________________________________________________ 9
375MHz Quad Closed-Loop Video Buffers, AV = +1 and +2 MAX496/MAX497
MAX496/MAX497 MAX496/MAX497
50
100
50
100
VIN = 4Vp-p, f = 10MHz, RS = 75
50
100
50
100
50
100
50
100
50
100
VIN = 4Vp-p, f = 10MHz, RS = 75
50
100
a) ADJACENT CHANNEL
Figure 4. Crosstalk: a) Adjacent Channel; b) All-Hostile
b) ALL-HOSTILE
Total Noise
The MAX496/MAX497's low input current noise of 2pA/Hz and voltage noise of 5.6nV/Hz provide for lower total noise compared to typical current-modefeedback amplifiers, which usually have significantly higher input current noise. The input current noise multiplied by the feedback resistor is the dominant noise source of current-mode-feedback amplifiers.
Coaxial Cable Drivers
High-speed performance, excellent output current capability, and an internally fixed gain of +2 make the MAX497 ideal for driving back-terminated 50 or 75 coaxial cables to 2.8V. In a typical application, the MAX497 drives a back-terminated 75 video cable (Figure 1). The back-termination resistor (at the MAX497's output) matches the impedance of the cable's driven end to the cable's impedance, to eliminate signal reflections. This, along with the load-termination resistor, forms a voltage divider with the load impedance, which attenuates the signal at the cable output by one-half. The MAX497 operates with an internal +2V/V closed-loop gain to provide unity gain at the cable's output.
Differential Gain and Phase Errors
Differential gain and phase errors are critical specifications for a buffer in composite (NTSC, PAL, SECAM) video applications, because these errors correspond directly to color changes in the displayed picture of composite video systems. The MAX496/MAX497's ultra-low differential gain and phase errors (0.01%/ 0.01) make them ideal in broadcast-quality composite video applications.
Capacitive Load Driving
In most amplifier circuits, driving large capacitive loads increases the likelihood of oscillation. This is especially true for circuits with high loop gains, such as voltage followers. The amplifier's output resistance and the capacitive load form an RC filter that adds a pole to the loop response. If the pole frequency is low enough (as when driving a large capacitive load), the circuit phase margin is degraded and oscillation may occur.
Distribution Amplifier
The circuit in Figure 3 is a one-to-four distribution amplifier using a single MAX496 or MAX497 IC. A one-to-eight distribution amplifier can be implemented with a MAX496 or MAX497 by driving an additional cable from each of the four outputs. When driving more than four outputs from a single device, see the Continuous Power Dissipation specifications in the Absolute Maximum Ratings.
10
______________________________________________________________________________________
375MHz Quad Closed-Loop Video Buffers, AV = +1 and +2 MAX496/MAX497
6 4 2 GAIN (dB)* GAIN (dB) 0 -2 -4 -6 -8 -10 -12 1M 10M 100M 1G FREQUENCY (Hz)
* -3dB ATTENUATION DUE TO RISO NOT SHOWN
RL = 50 RISO = 0
CL = 60pF CL = 22pF
CL = 47pF CL = 10pF
MAX496/97-5a
4 3 2 1 0 -1 -2 -3 -4 -5 1M
RL = 50 RISO = 20 CL = 22pF CL = 10pF CL = 47pF CL = 60pF
CL = 0pF
10M
100M
1G
FREQUENCY (Hz)
Figure 5a. MAX496 Small-Signal Gain vs. Frequency and Load Capacitor (RL = 50, RISO = 0)
Figure 5b. MAX496 Small-Signal Gain vs. Frequency and Load Capacitor (RL = 50, RISO = 20)
MAX496/97-5c
15 10 5 GAIN (dB) 0 -5 -10 -15 -20 -25 -30 1M
RL = RISO = 0 8
CL = 68pF CL = 20pF
CL = 47pF
15 10 5 GAIN (dB) 0 -5 -10 -15 -20 -25 -30
RL = RISO = 20 8
CL = 47pF
CL = 10pF CL = 0pF
CL = 68pF CL = 22pF
CL = 10pF
10M
100M
1G
1M
10M
100M
1G
FREQUENCY (Hz)
FREQUENCY (Hz)
Figure 5c. MAX496 Small-Signal Gain vs. Frequency and Load Capacitor (RL = , RISO = 0)
Figure 5d. MAX496 Small-Signal Gain vs. Frequency and Load Capacitor (RL = , RISO = 20)
The MAX496/MAX497 drive capacitive loads up to 75pF without sustained oscillation, although some peaking may occur. When driving larger capacitive loads, or to reduce peaking, add an isolation resistor (RISO) between the output and the capacitive load (Figures 5a-5d).
Grounding and Layout
The MAX496/MAX497 bandwidths are in the RF frequency range. Depending on the size of the PC board used and the frequency of operation, it may be necessary to use Micro-strip or Stripline techniques. To realize the full AC performance of these high-speed buffers, pay careful attention to power-supply bypassing and board layout. The PC board should have at least two layers (wire-wrap boards are too inductive, bread boards are too capacitive), with one side a signal layer and the other a large, low-impedance ground plane. With multilayer boards, locate the ground plane on the layer that is not dedicated to a specific signal trace. The ground plane should be as free from voids as possible. Connect all ground pins to the ground plane.
Connect both positive power-supply pins together and bypass with a 0.10F ceramic capacitor at each power supply pin, as close to the device as possible. Repeat the same for the negative power-supply pins. The capacitor lead lengths should be as short as possible to minimize lead inductance; surface-mount chip capacitors are ideal. A large-value (4.7F or greater) tantalum or electrolytic bypass capacitor on each supply may be required for high-current loads. The location of this capacitor is not critical. The MAX496/MAX497's analog input pins are isolated with ground pins to minimize parasitic coupling, which can degrade crosstalk and/or amplifier stability. Keep signal paths as short as possible to minimize inductance. Ensure that all input channel traces are the same length to maintain the phase relationship between the four channels. To further reduce crosstalk, connect the coaxial-cable shield to the ground side of the 75 terminating resistor at the ground plane, and terminate all unused inputs ground and outputs with a 100 or 150 resistor to ground.
11
______________________________________________________________________________________
MAX496/97-5d
20
20
MAX496/97-5b
8
5
375MHz Quad Closed-Loop Video Buffers, AV = +1 and +2 MAX496/MAX497
___________________Chip Topography
GND IN0 OUT0 VCC
GND IN1 OUT1 VEE 0.101" (2.56mm)
OUT2 GND IN2 VEE
GND
IN3
VCC
OUT3
0.076" (1.930mm)
TRANSISTOR COUNT: 544 SUBSTRATE CONNECTED TO VEE
________________________________________________________Package Information
SOICN.EPS
12
______________________________________________________________________________________

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