Page 1
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_______________General Description
The MAX4108/MAX4109/MAX4308/MAX4309 op amps
combine ultra-high-speed performance with ultra-lowdistortion operation. The MAX4108 is compensated for
unity-gain stability; the MAX4109, MAX4308, and
MAX4309 are compensated for minimum closed-loop
gains (A
VCL
) of 2V/V, 5V/V, and 10V/V, respectively.
The MAX4108 delivers a 400MHz unity-gain bandwidth
with a 1200V/µs slew rate. An ultra-low-distortion design
provides an unprecedented spurious-free dynamic
range of -93dBc (MAX4108) at 5MHz (V
OUT
= 2Vp-p, R
L
= 100Ω), making these amplifiers ideal for high-performance RF signal processing.
These high-speed op amps feature a wide output voltage swing and a high-current output-drive capability of
90mA.
________________________Applications
High-Speed ADC/DAC Preamp
RGB and Composite Video
High-Performance Receivers
Pulse/RF Amplifier
Active Filters
Ultrasound
Broadcast and High-Definition TV
____________________________Features
♦ High Speed:
400MHz Unity-Gain Bandwidth (MAX4108)
225MHz -3dB Bandwidth (A
VCL
= +2, MAX4109)
220MHz -3dB Bandwidth (A
VCL
= +5, MAX4308)
200MHz -3dB Bandwidth (A
VCL
= +10, MAX4309)
♦ 1200V/µs Slew Rate
♦ Excellent Spurious-Free Dynamic Range:
-93dBc at fC= 5MHz (MAX4108)
-90dBc at fC= 5MHz (MAX4109)
♦ 100MHz 0.1dB Gain Flatness (MAX4108)
♦ High Full-Power Bandwidth: 300MHz
(MAX4108, VO= 2Vp-p)
♦ High Output Drive: 90mA
♦ Output Short-Circuit Protected
♦ Low Differential Gain/Phase: 0.004%/0.008°
MAX4108/MAX4109/MAX4308/MAX4309
400MHz, Ultra-Low-Distortion Op Amps
________________________________________________________________
Maxim Integrated Products
1
19-0461; Rev 2; 4/97
PART
MAX4108ESA
MAX4109ESA
-40°C to +85°C
-40°C to +85°C
TEMP. RANGE PIN-PACKAGE
8 SO
8 SO
______________Ordering Information
OUT
IN+
V
EE
V
EE
1
2
8
7
V
CC
V
CC
IN-
N.C.
MAX4108
MAX4109
MAX4308
MAX4309
SO
TOP VIEW
3
4
6
5
__________________Pin Configuration
300Ω
300Ω
300Ω
300Ω
53.6Ω*
60Ω*
DIFFERENCE AMPLIFIER/ADC PREAMPLIFIER
10Ω
MAX4109
12-BIT ADC
* USED TO MATCH A 50Ω
SOURCE IMPEDANCE
________Typical Application Circuit
EVALUATION KIT
AVAILABLE
MAX4308ESA
MAX4309ESA
-40°C to +85°C
-40°C to +85°C 8 SO
8 SO
Page 2
MAX4108/MAX4109/MAX4308/MAX4309
400MHz, Ultra-Low-Distortion Op Amps
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VCC= +5V, VEE= -5V, TA= T
MIN
to T
MAX
, typical values are at TA= +25°C, unless otherwise noted.)
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
Voltage on Any Pin to Ground or
Any Other Pin..............................(V
EE
- 0.3V) to (VCC+ 0.3V)
Short-Circuit Duration (OUT to GND).........................Continuous
Continuous Power Dissipation (T
A
= +70°C)
SO (derate 5.88mW/°C above +70°C)........................471mW
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range.............................-65°C to +150°C
Junction Temperature......................................................+150°C
Lead Temperature (soldering, 10sec).............................+300°C
V
OUT
= 0V
Short to ground
V
OUT
= 0V
RL= 33Ω, TA= 0°C to +85°C
VIN= 0V
V
OUT
= 0V, VIN= -V
OS
V
OUT
= 0V, VIN= -V
OS
Either input
VCM= ±2.5V
Either input
f = 10kHz
CONDITIONS
mA100I
SC
Short-Circuit Output Current
mA65 90I
OUT
Output Current Drive
mA20 27I
S
Quiescent Supply Current
dB70 100CMRCommon-Mode Rejection
pA/√Hz2i
n
Input Current Noise
µV/°C13TCV
OS
Input Offset Voltage Drift
mV1 8V
OS
Input Offset Voltage
6
µA12 34I
B
Input Bias Current
µA0.05 2.5I
OS
Input Offset Current
MΩ1.5R
INCM
Common-Mode Input
Resistance
pF1C
INCM
Common-Mode Input
Capacitance
UNITSMIN TYP MAXSYMBOLPARAMETER
VS= ±4.5V to ±5.5V dB70 90PSRPower-Supply Rejection
RL= 100Ω
RL= ∞
V
2.5 to 2.7 to
-3.1 -3.7
V
OUT
Output Voltage Swing
2.5 to 2.9 to
-3.1 -3.8
V
OUT
= ±2.0V, VCM= 0V, RL= 100Ω dBA
OL
Open-Loop Voltage Gain 70 100
V-2.5 2.5V
CM
Common-Mode Input Voltage
µV
RMS
75
fB= 1MHz to 100MHz nA
RMS
25I
n
Integrated Current Noise
nV/√Hzf = 10kHze
n
Input Voltage Noise
fB= 1MHz to 100MHzE
nRMS
Integrated Voltage Noise
225MAX4109
MHz
220
200
MAX4308
BW
-3dB
-3dB Bandwidth V
OUT
≤ 0.1V
RMS
MAX4309
400MAX4108
DC SPECIFICATIONS (RL= ∞)
AC SPECIFICATIONS (RL= 100Ω)
Page 3
MAX4108/MAX4109/MAX4308/MAX4309
400MHz, Ultra-Low-Distortion Op Amps
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VCC= +5V, VEE= -5V, TA= T
MIN
to T
MAX
, typical values are at TA= +25°C, unless otherwise noted.)
-50mV ≤ V
OUT
≤ 50mV
-2V ≤ V
OUT
≤ 2V
To 0.01%
To 0.1%
MAX4109, A
VCL
= +2
MAX4108, A
VCL
= +1
MAX4309
MAX4308
MAX4108
MAX4309, A
VCL
= +10
MAX4109
MAX4308, A
VCL
= +5
CONDITIONS
%0.004DGDifferential Gain
nsRise/Fall Times
2
f = 3.58MHz, RL= 150Ω degrees
3
tR, t
F
0.008
ns
12
t
S
Settling Time
DP
8
Differential Phase
V/µs1200
pF2C
IN
Input Capacitance
f = 10MHz Ω1R
OUT
MHz
30
BW
0.1dB
0.1dB Gain Flatness
Output Resistance
100
25
100
MHz
130
FPBWFull-Power Bandwidth
190
300
200
UNITSMIN TYP MAXSYMBOLPARAMETER
f = 3.58MHz, RL= 150Ω
10% to 90%
-1V ≤ V
OUT
≤ 1V
-2V ≤ V
OUT
≤ 2V
V
OUT
= 2Vp-p
SRSlew Rate
fC= 20MHz,
RL= 100Ω
fC= 5MHz,
RL= 100Ω
-81
-93
MAX4108,
V
OUT
= 2Vp-p, A
VCL
= +1
fC= 20MHz,
RL= 100Ω
fC= 5MHz,
RL= 100Ω
-80
-90
MAX4109,
V
OUT
= 2Vp-p, A
VCL
= +2
fC= 20MHz,
RL= 100Ω
fC= 5MHz,
R
L
= 100Ω
fC= 20MHz,
RL= 100Ω
fC= 5MHz,
RL= 100Ω
dBcSpurious-Free Dynamic Range
-80
-80
-83
-83
SFDR
MAX4309,
V
OUT
= 2Vp-p, A
VCL
= +10
MAX4308,
V
OUT
= 2Vp-p, A
VCL
= +5
MAX4308
MAX4108
dBmThird-Order Intercept
46
39
IP3 fC= 10MHz
36
43
MAX4109
MAX4309
AC SPECIFICATIONS (RL= 100Ω) (continued)
Page 4
MAX4108/MAX4109/MAX4308/MAX4309
400MHz, Ultra-Low-Distortion Op Amps
4 _______________________________________________________________________________________
__________________________________________Typical Operating Characteristics
(VCC= +5V, VEE= -5V, RL= 100Ω, TA= +25°C, unless otherwise noted.)
2
1
-8
0.1 1 10 100 1000
MAX4108
SMALL-SIGNAL GAIN vs. FREQUENCY
-6
-7
MAX4108/9-A
FREQUENCY (MHz)
NORMALIZED GAIN (dB)
-4
-5
-2
-3
0
-1
V
OUT
≤ 100mVp-p
A
VCL
= +1
A
VCL
= +2
2
1
0
-8
0.1 1 100 1000
MAX4109
SMALL-SIGNAL GAIN vs. FREQUENCY
-4
-5
-6
-7
-1
-2
-3
MAX4108/9-C
FREQUENCY (MHz)
NORMALIZED GAIN (dB)
10
A
VCL
= +5
A
VCL
= +2
V
OUT
≤ 100mVp-p
2
1
0
-8
1 100 1000
MAX4109
LARGE-SIGNAL GAIN vs. FREQUENCY
-4
-5
-6
-7
-1
-2
-3
MAX4108/9-D
FREQUENCY (MHz)
NORMALIZED GAIN (dB)
10
V
OUT
= 2Vp-p
A
VCL
= +2
4
-6
0.1 10 1001 1000
MAX4309
SMALL-SIGNAL GAIN vs. FREQUENCY
-4
-5
MAX4308/9 TOCF
FREQUENCY (MHz)
NORMALIZED GAIN (dB)
-2
-3
0
-1
2
1
3
V
OUT
≤ 100mVp-p
A
VCL
= +20
A
VCL
= +10
4
3
-6
0.1 1 10 100 1000
MAX4108
LARGE-SIGNAL GAIN vs. FREQUENCY
-4
-5
MAX4108/9-B
FREQUENCY (MHz)
GAIN (dB)
-2
-3
0
-1
2
1
V
OUT
= 2Vp-p
A
VCL
= +1
4
-6
0.1 10 1001 1000
MAX4308
SMALL-SIGNAL GAIN vs. FREQUENCY
-4
-5
MAX4308/9 TOCE
FREQUENCY (MHz)
NORMALIZED GAIN (dB)
-2
-3
0
-1
2
1
3
V
OUT
≤ 100mVp-p
A
VCL
= +5
4
-6
0.1 10 1001 1000
MAX4308/MAX4309
LARGE-SIGNAL GAIN vs. FREQUENCY
-4
-5
MAX4308/9 TOCG
FREQUENCY (MHz)
NORMALIZED GAIN (dB)
-2
-3
0
-1
2
1
3
V
OUT
= 2Vp-p
MAX4309
A
VCL
= +10
MAX4308
A
VCL
= +5
-50
-40
-110
0.1 100
-80
-100
-90
-60
-70
MAX4108/9-H
FREQUENCY (MHz)
HARMONIC DISTORTION (dBc)
1 10
MAX4108
HARMONIC DISTORTION vs. FREQUENCY
2ND HARMONIC
3RD HARMONIC
V
OUT
= 2Vp-p
A
VCL
= +1
10
-110
0.1 100
-50
-90
-70
-10
-30
MAX4108/9-i
FREQUENCY (MHz)
HARMONIC DISTORTION (dBc)
1 10
2ND HARMONIC
V
OUT
= 2Vp-p
A
VCL
= +2
MAX4109
HARMONIC DISTORTION vs. FREQUENCY
3RD HARMONIC
Page 5
MAX4108/MAX4109/MAX4308/MAX4309
400MHz, Ultra-Low-Distortion Op Amps
_______________________________________________________________________________________
5
-20
-30
-100
0.1 101 100
MAX4308/MAX4309
HARMONIC DISTORTION vs.FREQUENCY
-80
-90
-70
-50
-60
-40
MAX4108/09 TOCJ
FREQUENCY (MHz)
HARMONIC DISTORTION (dBc)
V
OUT
= 2Vp-p
MAX4308: A
VCL
= +5
MAX4309: A
VCL
= +10
2ND HARMONIC
3RD
HARMONIC
-40
-30
-100
10 1000
-70
-90
-80
-50
-60
MAX4108/9-L
RESISTIVE LOAD (Ω)
HARMONIC DISTORTION (dBc)
100
2ND HARMONIC
A
VCL
= +2
V
OUT
= 2Vp-p
f
O
= 20MHz
MAX4109
HARMONIC DISTORTION vs. LOAD
3RD HARMONIC
-100
-90
-80
-70
-60
-50
-40
-30
-20
10 100 1000
MAX4308/MAX4309
HARMONIC DISTORTION vs. LOAD
MAX4108/09 TOCM
RESISTIVE LOAD (Ω)
HARMONIC DISTORTION (dBc)
V
OUT
= 2Vp-p
f
O
= 5MHz
MAX4308: A
VCL
= +5
MAX4309: A
VCL
= +10
3RD HARMONIC
2ND HARMONIC
-40
-30
-100
0.1 10
-70
-90
-80
-50
-60
MAX4108/9-N
OUTPUT SWING (Vp-p)
HARMONIC DISTORTION (dBc)
1
2ND HARMONIC
A
VCL
= +1
V
OUT
= 2Vp-p
f
O
= 20MHz
MAX4108
HARMONIC DISTORTION vs. OUTPUT SWING
3RD HARMONIC
-40
-30
-100
0.1 10
-70
-90
-80
-50
-60
MAX4108/9-O
OUTPUT SWING (Vp-p)
HARMONIC DISTORTION (dBc)
1
A
VCL
= +2
V
OUT
= 2Vp-p
f
O
= 20MHz
MAX4109
HARMONIC DISTORTION vs. OUTPUT SWING
3RD HARMONIC
2ND HARMONIC
-100
-90
-80
-70
-60
-50
-40
-30
-20
0.1 1 10
MAX4308/MAX4309
HARMONIC DISTORTION
vs. OUTPUT SWING
MAX4108/09 TOCP
RESISTIVE LOAD (Ω)
HARMONIC DISTORTION (dBc)
V
OUT
= 2Vp-p
f
O
= 5MHz
MAX4308: A
VCL
= +5
MAX4309: A
VCL
= +10
3RD HARMONIC
2ND HARMONIC
40
45
10
1 100
25
15
20
35
30
MAX4108/9-Q
FREQUENCY (MHz)
THIRD-ORDER INTERCEPT (dBm)
10
MAX4109
TWO-TONE THIRD-ORDER INTERCEPT
vs. FREQUENCY
____________________________Typical Operating Characteristics (continued)
(VCC= +5V, VEE= -5V, RL= 100Ω, TA= +25°C, unless otherwise noted.)
-40
-30
-100
10 1000
-70
-90
-80
-50
-60
MAX4108/9-K
RESISTIVE LOAD (Ω)
HARMONIC DISTORTION (dBc)
100
2ND HARMONIC
A
VCL
= +1
V
OUT
= 2Vp-p
f
O
= 20MHz
MAX4108
HARMONIC DISTORTION vs. LOAD
3RD HARMONIC
100
1
1 10k 100k 1M
10
MAX4108/9-TOCR
FREQUENCY (Hz)
10010 1k
INPUT VOLTAGE NOISE
vs. FREQUENCY
VOLTAGE NOISE (nV√Hz)
Page 6
MAX4108/MAX4109/MAX4308/MAX4309
400MHz, Ultra-Low-Distortion Op Amps
6 _______________________________________________________________________________________
____________________________Typical Operating Characteristics (continued)
(VCC= +5V, VEE= -5V, RL= 100Ω, TA= +25°C, unless otherwise noted.)
100
100
MAX4109
DIFFERENTIAL GAIN AND PHASE
(R
L
= 75Ω)
IRE
IRE
DIFF PHASE (deg)
DIFF GAIN (%)
MAX4108/9-V
0.004
0.002
0.006
0.000
-0.002
0
0
A
VCL
= +2V
A
VCL
= +2V
0.004
0.002
0.006
0.000
-0.002
100
MAX4308
DIFFERENTIAL GAIN AND PHASE
(R
L
= 150Ω)
IRE
IRE
DIFF PHASE (deg)
DIFF GAIN (%)
0
MAX4108/9-W
1000
A
VCL
= +5V
A
VCL
= +5V
0.000
-0.002
0.002
-0.004
-0.006
0.002
0.000
0.004
-0.002
-0.004
IN
OUT
GND
GND
TIME (10ns/div)
MAX4108
LARGE-SIGNAL PULSE RESPONSE
(A
VCL
= +1)
MAX4108/9-AA
VOLTAGE
(500mV/div)
100
MAX4109
DIFFERENTIAL GAIN AND PHASE
(R
L
= 150Ω)
IRE
IRE
DIFF PHASE (deg)
DIFF GAIN (%)
MAX4108/9-U
100
0
0
A
VCL
= +2V
A
VCL
= +2V
0.000
-0.002
0.002
-0.004
-0.006
0.002
0.000
0.004
-0.002
-0.004
100
MAX4108
DIFFERENTIAL GAIN AND PHASE
(R
L
= 75Ω)
IRE
IRE
DIFF PHASE (deg)
DIFF GAIN (%)
MAX4108/9-T
100
0
0
A
VCL
= +1V
A
VCL
= +1V
0.006
0.004
0.002
0.008
0.000
-0.002
0.004
0.002
0.006
0.000
-0.002
100
MAX4108
DIFFERENTIAL GAIN AND PHASE
(R
L
= 150Ω)
IRE
IRE
DIFF PHASE (deg)
DIFF GAIN (%)
0
MAX4108/9-S
1000
A
VCL
= +1V
A
VCL
= +1V
0.002
0.000
0.004
-0.002
-0.004
0.002
0.000
0.004
-0.002
-0.004
100
MAX4309
DIFFERENTIAL GAIN AND PHASE
(R
L
= 150Ω)
IRE
IRE
DIFF PHASE (deg)
DIFF GAIN (%)
0
MAX4108/9-X
1000
A
VCL
= +10V
A
VCL
= +10V
0.002
0.000
0.004
-0.002
-0.004
0.002
0.000
-0.002
-0.004
-0.006
-0.008
-0.010
VOLTAGE
(10mV/div)
OUT
GND
GND
TIME (10ns/div)
MAX4108
SMALL-SIGNAL PULSE RESPONSE
(A
VCL
= +2)
MAX4108/9-Z
IN
VOLTAGE
(20mV/div)
OUT
GND
GND
TIME (10ns/div)
MAX4108
SMALL-SIGNAL PULSE RESPONSE
(A
VCL
= +1)
MAX4108/9-Y
IN
Page 7
MAX4108/MAX4109/MAX4308/MAX4309
400MHz, Ultra-Low-Distortion Op Amps
_______________________________________________________________________________________
7
MAX4309
SMALL-SIGNAL PULSE RESPONSE
(A
VCL
= +10)
IN
OUT
GND
GND
TIME (10ns/div)
MAX4108/9GG
VOLTAGE
(25mV/div)
MAX4309
SMALL-SIGNAL PULSE RESPONSE
(A
VCL
= +20)
IN
OUT
GND
GND
TIME (10ns/div)
MAX4108/9HH
VOLTAGE
(25mV/div)
MAX4309
LARGE-SIGNAL PULSE RESPONSE
(A
VCL
= +20)
IN
OUT
GND
GND
TIME (10ns/div)
MAX4108/9JJ
VOLTAGE
(500mV/div)
MAX4308
LARGE-SIGNAL PULSE RESPONSE
(A
VCL
= +5)
IN
OUT
GND
GND
TIME (10ns/div)
MAX4108/9FF
VOLTAGE
(1V/div)
MAX4309
LARGE-SIGNAL PULSE RESPONSE
(A
VCL
= +10)
IN
OUT
GND
GND
TIME (10ns/div)
MAX4108/9ii
VOLTAGE
(500mV/div)
____________________________Typical Operating Characteristics (continued)
(VCC= +5V, VEE= -5V, RL= 100Ω, TA= +25°C, unless otherwise noted.)
IN
OUT
GND
GND
TIME (10ns/div)
MAX4109
SMALL-SIGNAL PULSE RESPONSE
(A
VCL
= +2)
MAX4108/9-CC
VOLTAGE
(10mV/div)
MAX4109
LARGE-SIGNAL PULSE RESPONSE
(A
VCL
= +2)
IN
OUT
GND
GND
TIME (10ns/div)
MAX4108/9-DD
VOLTAGE
(500mV/div)
IN
OUT
GND
GND
TIME (10ns/div)
MAX4108
LARGE-SIGNAL PULSE RESPONSE
(A
VCL
= +2)
MAX4108/9-BB
VOLTAGE
(500mV/div)
MAX4308
SMALL-SIGNAL PULSE RESPONSE
(A
VCL
= +5)
IN
OUT
GND
GND
TIME (10ns/div)
MAX4108/9EE
VOLTAGE
(100mV/div)
Page 8
MAX4108/MAX4109/MAX4308/MAX4309
400MHz, Ultra-Low-Distortion Op Amps
8 _______________________________________________________________________________________
____________________________Typical Operating Characteristics (continued)
(VCC= +5V, VEE= -5V, RL= 100Ω, TA= +25°C, unless otherwise noted.)
1000
0.1
0.1 1 10 100 1000
CLOSED-LOOP OUTPUT IMPEDANCE
vs. FREQUENCY
1
MAX4108/9-MM
FREQUENCY (MHz)
OUTPUT IMPEDANCE (Ω)
10
100
100
90
0
0.2 1 10 100 1000
POWER-SUPPLY REJECTION
vs. FREQUENCY
20
10
MAX4108/9-KK
FREQUENCY (MHz)
POWER-SUPPLY REJECTION (dB)
40
30
60
50
80
70
MAX4108/MAX4308
MAX4109/
MAX4309
110
100
10
0.1 1 10 100 1000
COMMON-MODE REJECTION
vs. FREQUENCY
30
20
MAX4108/9-LL
FREQUENCY (MHz)
COMMON-MODE REJECTION (dB)
50
40
70
60
90
80
MAX4108/MAX4308
MAX4109/
MAX4309
4.0
3.5
3.0
0
10 5030 9070 110 130 150
OUTPUT SWING
vs. LOAD RESISTANCE
0.5
MAX4108/9-NN
LOAD RESISTANCE (Ω)
OUTPUT SWING (V
PEAK
)
1.5
1.0
2.0
2.5
2.0
1.8
1.6
0.4
-75 -25-50 50250 75 100 125
INPUT OFFSET VOLTAGE
vs. TEMPERATURE
0.6
MAX4108/9-OO
TEMPERATURE (°C)
VOLTAGE (mV)
1.0
0.8
1.2
1.4
25
21
23
19
17
5
-75 -25-50 50250 75 100 125
INPUT BIAS CURRENT
vs. TEMPERATURE
7
MAX4108/9-PP
TEMPERATURE (°C)
CURRENT (µA)
11
9
13
15
30
20
-30
-75 -25-50 50250 75 100 125
POWER-SUPPLY CURRENT
vs. TEMPERATURE
-20
-10
MAX4108/9-RR
TEMPERATURE (°C)
CURRENT (mA)
10
0
NEGATIVE SUPPLY CURRENT
POSITIVE SUPPLY CURRENT
5.0
3.0
4.0
-5.0
-75 -25-50 50250 75 100 125
OUTPUT SWING
vs. TEMPERATURE
-3.0
-4.0
-2.0
-1.0
MAX4108/9-SS
TEMPERATURE (°C)
OUTPUT SWING (V)
2.0
1.0
0.0
RL = ∞
RL = ∞
RL = 100Ω
RL = 100Ω
0.100
0.020
-75 -25-50 50250 75 100 125
INPUT OFFSET CURRENT
vs. TEMPERATURE
0.040
MAX4108/9-QQ
TEMPERATURE (°C)
CURRENT (µA)
0.080
0.060
Page 9
MAX4108/MAX4109/MAX4308/MAX4309
400MHz, Ultra-Low-Distortion Op Amps
_______________________________________________________________________________________ 9
_______________Detailed Description
Choosing Resistor Values
Unity-Gain Configuration
The MAX4108 is internally compensated for unity gain.
When configured for unity gain, the device requires a
small resistor in series with the feedback path. This
resistor improves the AC response by reducing the Q
of the tank circuit, which is formed by parasitic feedback inductance and capacitance.
Inverting and Noninverting Configurations
The values of the gain-setting feedback and input resistors are important design considerations. Large resistor
values will increase voltage noise, and will interact with
the amplifier’s input and PC board capacitance to generate undesirable poles and zeros, which can decrease
bandwidth or cause oscillations. For example, a noninverting gain of +2, using 1kΩ resistors combined with
2pF of input capacitance and 0.5pF of board capacitance, will cause a feedback pole at 128MHz. If this
pole is within the anticipated amplifier bandwidth, it will
jeopardize stability. Reducing these 1kΩ resistors to
100Ω will extend the pole frequency to 1.28GHz, but
could limit output swing by adding 200Ω in parallel with
the amplifier’s load. Clearly, the selection of resistor values must be tailored to the specific application.
The MAX4108/MAX4109/MAX4308/MAX4309 are ultralow-distortion, high-bandwidth op amps. The output
distortion will be degraded as the total load resistance
seen by the amplifier decreases. To minimize distortion
products, keep the input and gain-setting resistors relatively large. A 500Ω feedback resistor combined with
an appropriate input resistor to set the gain will provide
excellent AC performance without significantly increasing distortion.
_____________________Pin Description
PIN NAME FUNCTION
1 N.C. No Connection. Not internally connected.
2 IN- Inverting Input
3 IN+ Noninverting Input
4, 5 V
EE
Negative Power Supply, connect to -5VDC.
6 OUT Amplifier Output
7, 8 V
CC
Positive Power Supply, connect to +5VDC.
Figure 1a. Using an Isolation Resistor for High Capacitive
Loads
0
MAX4108/9-1B
ISOLATION RESISTANCE (Ω)
20
25
15
10
5
19010 40 70 100 130 160 220
CAPACITANCE (pF)
MAX4109/MAX4309
MAX4108
MAX4308
Figure 1b. Optimal Isolation Resistor (RS) vs. Capacitive Load
R
G
V
IN
PART
MAX4108
MAX4109
MAX4308
MAX4309
R
F
R
S
C
L
RF (Ω)
RG (Ω)
GAIN (V/V)
24
∞
500
500
500
125
500
56
1
2
5
10
R
L
Page 10
MAX4108/MAX4109/MAX4308/MAX4309
400MHz, Ultra-Low-Distortion Op Amps
10 ______________________________________________________________________________________
12
-8
-6
0.1 1 10010 1000
0
MAX4108/9-2A
FREQUENCY (MHz)
CLOSED-LOOP GAIN (dB)
6
10
-2
-4
2
4
8
RS = 0Ω
A
VCL
= +1
CL = 15pF
CL = 5pF
CL = 10pF
Figure 2a. MAX4108 Response vs. Capacitive Load—No
Resistive (R
S
) Isolation (circuit shown in Figure 1a)
20
0
0.1 1 10010 1000
8
MAX4108/9-2B
FREQUENCY (MHz)
CLOSED-LOOP GAIN (dB)
14
18
2
6
4
10
12
16
RS = 0Ω
A
VCL
= +2
CL = 5pF
CL = 10pF
CL = 15pF
Figure 2b. MAX4109 Response vs. Capacitive Load—No
Resistive (R
S
) Isolation (circuit shown in Figure 1a)
4
-6
-5
0.1 1 10010 1000
-2
MAX4108/9-2C
FREQUENCY (MHz)
NORMALIZED GAIN (dB)
1
3
-3
-4
-1
0
2
CL = 15pF
CL = 5pF
CL = 10pF
RS = 0Ω
A
VCL
= +5
Figure 2c. MAX4308 Response vs. Capacitive Load—No
Resistive (R
S
) Isolation (circuit shown in Figure 1a)
4
-6
-5
0.1 1 10010 1000
-2
MAX4108/9-2D
FREQUENCY (MHz)
NORMALIZED GAIN (dB)
1
3
-3
-4
-1
0
2
CL = 15pF
CL = 5pF
CL = 10pF
RS = 0Ω
A
VCL
= +10
Figure 2d. MAX4309 Response vs. Capacitive Load—No
Resistive (R
S
) Isolation (circuit shown in Figure 1a)
Driving Capacitive Loads
The MAX4108/MAX4109/MAX4308/MAX4309 are optimized for AC performance. They are not designed to
drive highly reactive loads. Reactive loads will
decrease phase margin and may produce excessive
ringing and oscillation. Figure 1a shows a circuit that
eliminates this problem, and Figure 1b is a graph of the
optimal isolation resistor (R
S
) vs. capacitive load.
Figures 2a–2d show how a capacitive load causes
excessive peaking of the amplifier’s bandwidth if the
capacitive load is not isolated (RS) from the amplifier. A
small isolation resistor (usually 15Ω to 22Ω) placed
Page 11
MAX4108/MAX4109/MAX4308/MAX4309
400MHz, Ultra-Low-Distortion Op Amps
______________________________________________________________________________________ 11
before the reactive load prevents ringing and oscillation. At higher capacitive loads, AC performance will be
controlled by the interaction of the load capacitance
and isolation resistor. Figures 3a–3c show the effect of
an isolation resistor on the MAX4108/MAX4109/
MAX4308/MAX4309 closed-loop response.
Coaxial cable and other transmission lines are easily
driven when terminated at both ends with their characteristic impedance. When driving back-terminated
transmission lines, the capacitance of the transmission
line is essentially eliminated.
ADC Input Buffers
Input buffer amplifiers can be a source of significant
errors in high-speed ADC applications. The input buffer
is usually required to rapidly charge and discharge the
ADC’s input, which is often capacitive (see the section
Driving Capacitive Loads
). In addition, a high-speed
ADC’s input impedance often changes very rapidly
during the conversion cycle, requiring an amplifier with
very low output impedance at high frequencies to maintain measurement accuracy. The combination of high
speed, fast slew rate, low noise, and a low and stable
distortion over load makes the MAX4108/MAX4109/
MAX4308/MAX4309 ideally suited for use as buffer
amplifiers in high-speed ADC applications.
12
-8
0.1 1 10010 1000
-2
MAX4108/9-3A
FREQUENCY (MHz)
CLOSED-LOOP GAIN (dB)
6
4
10
-6
-4
0
2
8
CL = 10pF
A
VCL
= +1
RS = 30Ω
RS = 10Ω
RS = 22Ω
Figure 3a. MAX4108 Response vs. Capacitive Load with
Resistive (R
S
) Isolation (circuit shown in Figure 1a)
11
1
0.1 1 10010 1000
4
5
MAX4108/9-3B
FREQUENCY (MHz)
CLOSED-LOOP GAIN (dB)
8
10
2
3
6
7
9
RS = 15Ω
RS = 8.2Ω
CL = 10pF
A
VCL
= +2
Figure 3b. MAX4308 Response vs. Capacitive Load with
Resistive (R
S
) Isolation (circuit shown in Figure 1a)
4
-6
0.1 1 10010 1000
-2
MAX4108/9-3C
FREQUENCY (MHz)
NORMALIZED GAIN (dB)
1
3
-5
-3
-4
-1
0
2
CL = 10pF
A
V
= +5
RS = 8.2Ω
R
S
= 15Ω
R
S
= 47Ω
Figure 3c. MAX4108/MAX4309 Response vs. Capacitive Load
with Resistive (R
S
) Isolation (circuit shown in Figure 1a)
Page 12
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
© 1997 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
MAX4108/MAX4109/MAX4308/MAX4309
400MHz, Ultra-Low-Distortion Op Amps
___________________Chip Information
TRANSISTOR COUNT: 57
SUBSTRATE CONNECTED TO V
EE
________________________________________________________Package Information
SOICN.EPS
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