EVALUATION KIT MANUAL
19-4757; Rev 3; 10/98
FOLLOWS DATA SHEET
740MHz, Low-Noise, Low-Distortion
Op Amps in SOT23-5
MAX4104/MAX4105/MAX4304/MAX4305
General Description Features
The MAX4104/MAX4105/MAX4304/MAX4305 op amps
feature ultra-high speed, low noise, and low distortion in a SOT23 package. The unity-gain-stable MAX4104 requires only 20mA of supply current while delivering 625MHz bandwidth and 400V/µs slew rate. The MAX4304, compensated for gains of +2V/V or greater, delivers a 730MHz bandwidth and a 1000V/µs slew rate. The MAX4105 is compensated for a minimum gain of +5V/V and delivers a 410MHz bandwidth and a 1400V/sec slew rate. The MAX4305 has +10V/V mini- mum gain compensation and delivers a 340MHz band- width and a 1400V/µs slew rate.
Low voltage noise density of 2.1nV/Hz and -88dBc spurious-free dynamic range make these devices ideal for low-noise/low-distortion video and telecommunica- tions applications. These op amps also feature a wide
Low 2.1nV/Hz Voltage Noise Density
Ultra-High 740MHz -3dB Bandwidth (MAX4304, AVCL = 2V/V)
100MHz 0.1dB Gain Flatness (MAX4104/4105)
1400V/µs Slew Rate (MAX4105/4305)
-88dBc SFDR (5MHz, RL = 100) (MAX4104/4304)
High Output Current Drive: ±70mA
Low Differential Gain/Phase Error: 0.01%/0.01° (MAX4104/4304)
Low ±1mV Input Offset Voltage
Available in Space-Saving 5-Pin SOT23 Package
output voltage swing of ±3.7V and ±70mA output current- Selector Guide
PART | MINIMUM STABLE GAIN (V/V) | BANDWIDTH (MHz) | PIN-PACKAGE |
MAX4104 | 1 | 625 | 5-pin SOT23, 8-pin SO |
MAX4304 | 2 | 740 | 5-pin SOT23, 8-pin SO |
MAX4105 | 5 | 410 | 5-pin SOT23, 8-pin SO |
MAX4305 | 10 | 340 | 5-pin SOT23, 8-pin SO |
drive capability. For space-critical applications, they
are available in a miniature 5-pin SOT23 package.
Applications
Video ADC Preamp
Pulse/RF Telecom Applications Video Buffers and Cable Drivers
Ultrasound Ordering Information
PART | TEMP. RANGE | PIN- PACKAGE | SOT TOP MARK |
MAX4104ESA | -40°C to +85°C | 8 SO | — |
MAX4104EUK-T | -40°C to +85°C | 5 SOT23-5 | ACCO |
Active Filters
ADC Input Buffers
Typical Application Circuit
8 to16-BIT HIGH-SPEED ADC | ||
304 |
INPUT
Ordering Information continued at end of data sheet.
Pin Configurations
TOPVIEW OUT 1 5 VCC MAX4104 VEE 2 MAX4105 MAX4304 MAX4305 IN+ 3 4 IN- SOT23-5 Pin Configurations continued at end of data sheet. |
MAX4
330
330
ADCBUFFER WITH GAIN (AVCL = 2V/V)
Maxim Integrated Products 1
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (VCC to VEE)................................................+12V
Voltage on Any Pin to Ground..........(VEE - 0.3V) to (VCC + 0.3V) Short-Circuit Duration (VOUT to GND)........................Continuous Continuous Power Dissipation (TA = +70°C)
5-pin SOT23 (derate 7.1mW/°C above +70°C)...........571mW 8-pin SO (derate 5.9mW/°C above +70°C).................471mW
Operating Temperature Range ...........................-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.
DC ELECTRICAL CHARACTERISTICS
(VCC = +5V, VEE = -5V, VCM = 0, RL = 100k, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER | SYMBOL | CONDITIONS | MIN | TYP | MAX | UNITS | |
Operating Supply Voltage Range | VCC/VEE | Guaranteed by PSRR test | ±3.5 | ±5 | ±5.5 | V | |
Input Offset Voltage | VOS | VOUT = 0 | MAX4_0_ESA | 1 | 6 | mV | |
MAX4_0_EUK | 1 | 8 | |||||
Input Offset-Voltage Drift | TCVOS | 2.5 | µV/°C | ||||
Input Bias Current | IB | 32 | 70 | µA | |||
Input Offset Current | IOS | 0.5 | 5.0 | µA | |||
Differential Input Resistance | RIN | -0.8V VIN 0.8V | 6 | k | |||
Common-Mode Input Resistance | RIN | Either input | 1.5 | M | |||
Input Common-Mode Voltage Range | VCM | Guaranteed by CMRR test | -2.8 | +4.1 | V | ||
Common-Mode Rejection Ratio | CMRR | -2.8V VCM 4.1V | 80 | 95 | dB | ||
Positive Power-Supply Rejection Ratio | PSSR+ | VCC = 3.5V to 5.5V | 75 | 85 | dB | ||
Negative Power-Supply Rejection Ratio | PSRR- | VEE = -3.5V to -5.5V | 55 | 65 | dB | ||
Quiescent Supply Current | IS | VOUT = 0 | 20 | 27 | mA | ||
Open-Loop Gain | AVOL | -2.8V VOUT 2.8V, RL = 100 | 55 | 65 | dB | ||
Output Voltage Swing | VOUT | RL = 100k | ±3.5 -3.7 to +3.8 | V | |||
RL = 100 | ±3.0 -3.5 to +3.4 | ||||||
Output Current Drive | IOUT | RL = 30 | ±53 | ±70 | mA | ||
Short-Circuit Output Current | ISC | RL = short to ground | 80 | mA | |||
Open-Loop Output Impedance | ZOUT | 9 | |
AC ELECTRICAL CHARACTERISTICS
(VCC = +5V, VEE = -5V, VCM = 0, RL = 100; AV = +1V/V for MAX4104, +2V/V for MAX4304, +5V/V for MAX4105, +10V/V for MAX4305;
TA = +25°C; unless otherwise noted.)
PARAMETER | SYMBOL | CONDITIONS | MIN TYP MAX | UNITS | ||
-3dB Bandwidth | BW(-3dB) | VOUT = 100mVp-p | MAX4104 | 625 | MHz | |
MAX4304 | 740 | |||||
MAX4105 | 410 | |||||
MAX4305 | 340 | |||||
0.1dB Bandwidth | BW(0.1) | VOUT = 100mVp-p | MAX4104 | 100 | MHz | |
MAX4304 | 60 | |||||
MAX4105 | 80 | |||||
MAX4305 | 70 | |||||
Full-Power Bandwidth | FPBW | VOUT = 2Vp-p | MAX4104 | 115 | MHz | |
MAX4304 | 285 | |||||
MAX4105 | 370 | |||||
MAX4305 | 320 | |||||
Slew Rate | SR | VOUT = 2Vp-p | MAX4104 | 400 | V/µs | |
MAX4304 | 1000 | |||||
MAX4105 | 1400 | |||||
MAX4305 | 1400 | |||||
Settling Time to 0.1% | tS | VOUT = 2Vp-p | to 0.1% | 20 | ns | |
to 0.01% | 25 | |||||
Spurious-Free Dynamic Range | SFDR | VOUT = 2Vp-p | MAX4104/ MAX4304 | fC = 5MHz | -88 | dBc |
fC = 20MHz | -67 | |||||
MAX4105/ MAX4305 | fC = 5MHz | -74 | ||||
fC = 20MHz | -61 | |||||
Differential Gain Error | DG | NTSC, RL = 150 | MAX4104/MAX4304 | 0.01 | % | |
MAX4105/MAX4305 | 0.02 | |||||
Differential Phase Error | DP | NTSC, RL = 150 | MAX4104/MAX4304 | 0.01 | degrees | |
MAX4105/MAX4305 | 0.02 | |||||
Input Voltage Noise Density | en | f = 1MHz | 2.1 | nV/Hz | ||
Input Current Noise Density | in | f = 1MHz | 3.1 | pA/Hz | ||
Output Impedance | ZOUT | f = 10MHz | 1 | |
Typical Operating Characteristics
(VCC = +5V, VEE = -5V, RF = 330, RL = 100, TA = +25°C, unless otherwise noted.)
MAX4104 SMALL-SIGNALGAIN
vs. FREQUENCY (AVCL = +1)
VOUT=100mVp-p
5
4
3
2
GAIN(dB)
1
0
-1
-2
-3
-4
-5
MAX4304 SMALL-SIGNALGAIN
vs. FREQUENCY (AVCL= +2)
VOUT=100mVp-p
MAX4104TOC01
5
4
NORMALIZEDGAIN(dB)
3
2
1
0
-1
-2
-3
-4
-5
MAX4105 SMALL-SIGNALGAIN
vs. FREQUENCY (AVCL= +5)
VOUT=100mVp-p
MAX4104TOC2
MAX4104TOC3
5
4
NORMALIZEDGAIN(dB)
3
2
1
0
-1
-2
-3
-4
-5
100k 1M 10M 100M 1G FREQUENCY(Hz)
MAX4305 SMALL-SIGNALGAIN
vs. FREQUENCY (AVCL= +10)
VOUT=100mVp-p
MAX4104TOC4
5
4
NORMALIZEDGAIN(dB)
3
2
1
0
-1
-2
-3
-4
-5
100k 1M 10M 100M 1G FREQUENCY(Hz)
MAX4104 GAIN FLATNESS
vs. FREQUENCY (AVCL= +1)
VOUT=100mVp-p
MAX4104TOC5
0.5
0.4
0.3
0.2
GAIN(dB)
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
0.5
0.4
NORMALIZEDGAIN(dB)
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
100k 1M 10M 100M 1G FREQUENCY(Hz)
MAX4304 GAIN FLATNESS
MAX4104TOC6
vs. FREQUENCY (AVCL= +2)
VOUT=100mVp-p
100k 1M 10M 100M 1G FREQUENCY(Hz)
MAX4105 GAIN FLATNESS
vs. FREQUENCY (AVCL= +5)
VOUT=100mVp-p
MAX4104TOC7
0.5
0.4
NORMALIZEDGAIN(dB)
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
100k | 1M | 10M | 100M | 1G | 100k | 1M | 10M | 100M | 1G | 100k | 1M | 10M | 100M | 1G |
FREQUENCY(Hz) | FREQUENCY(Hz) | FREQUENCY(Hz) |
-0.5
100k 1M 10M 100M 1G FREQUENCY(Hz)
MAX4305 GAIN FLATNESS
vs. FREQUENCY (AVCL= +10)
VOUT=100mVp-p
MAX4104TOC8
0.5
0.4
NORMALIZEDGAIN(dB)
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
100k 1M 10M 100M 1G FREQUENCY(Hz)
MAX4104 LARGE-SIGNALGAIN
vs. FREQUENCY (AVCL= +1)
VOUT=2Vp-p
MAX4104TOC9
5
4
3
2
GAIN(dB)
1
0
-1
-2
-3
-4
-5
Typical Operating Characteristics (continued)
(VCC = +5V, VEE = -5V, RF = 330, RL = 100, TA = +25°C, unless otherwise noted.)
MAX4304 LARGE-SIGNALGAIN
vs. FREQUENCY (AVCL= +2)
VOUT=2Vp-p
5
4
NORMALIZEDGAIN(dB)
3
2
1
0
-1
-2
-3
-4
-5
MAX4105 LARGE-SIGNALGAIN
vs. FREQUENCY (AVCL= +5)
VOUT=2Vp-p
MAX4104TOC10
5
4
NORMALIZEDGAIN(dB)
3
2
1
0
-1
-2
-3
-4
-5
MAX4305 LARGE-SIGNALGAIN
vs. FREQUENCY (AVCL= +10)
VOUT=2Vp-p
MAX4104TOC11
MAX4104TOC12
5
4
NORMALIZEDGAIN(dB)
3
2
1
0
-1
-2
-3
-4
-5
100k 1M 10M 100M 1G FREQUENCY(Hz)
100k 1M 10M 100M 1G FREQUENCY(Hz)
100k 1M 10M 100M 1G FREQUENCY(Hz)
MAX4104TOCO
0
POWER-SUPPLYREJECTION(dB)
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
POSITIVE POWER-SUPPLY REJECTION vs. FREQUENCY
MAX4104 TOCM
20
POWER-SUPPLYREJECTION(dB)
10
0
-10
-20
-30
-40
-50
-60
-70
-80
NEGATIVE POWER-SUPPLY REJECTION vs. FREQUENCY
MAX4104 TOCN
0
-10
-20
-30
CMR(dB)
-40
-50
-60
-70
-80
-90
-100
COMMON-MODEREJECTION vs. FREQUENCY
100k 1M 10M 100M 1G FREQUENCY(Hz)
100k 1M 10M 100M 1G FREQUENCY(Hz)
10k
100k
1M 10M 100M 1G FREQUENCY(Hz)
100
VOLTAGENOISEDENSITY vs. FREQUENCY (INPUT REFERRED)
CURRENT NOISEDENSITY vs. FREQUENC (INPUT REFERRED)
MAX4104TOC-Q
100
1000
CLOSED-LOOPOUTPUT IMPEDANCE vs. FREQUENCY
VOLTAGENOISEDENSITY(nV/ Hz)
MAX4104TOC-P
CURRENTNOISEDENSITY(pA/Hz)
OUTPUTIMPEDANCE( )
MAX4104TOC-R
100
10
10 10
1
0.1
1
1 10 100
1k 10k
100k 1M 10M
1
1 10 100
1k 10k
100k 1M 10M
0.01
100k 1M 10M 100M 1G
FREQUENCY(Hz)
FREQUENCY(Hz)
FREQUENCY(Hz)
DIFFGAIN(%)
0.005
0.000
-0.005
-0.010
-0.015
DIFFPHASE(deg)
0.015
0.010
0.005
0.000
-0.005
MAX4104/MAX4304 DIFFERENTIALGAINAND PHASE
RL=150 |
MAX4104TOC-S
0 100
RL=150 | |||||||||
0.03
DIFFGAIN(%)
0.02
0.01
0.00
-0.01
DIFFPHASE(deg)
0.025
0.020
0.015
0.010
0.005
0.000
-0.005
MAX4105/MAX4305 DIFFERENTIALGAINAND PHASE
RL=150 |
MAX4104TOCT
0 100
RL=150
0
-10
HARMONICDISTORTION(dBc)
-20
-30
-40
-50
-60
-70
-80
-90
-100
MAX4104/MAX4304 HARMONICDISTORTION vs. FREQUENCY
MAX4104TOC-U
VOUT=2Vp-p
2ND
H
ARMONIC
3RDHARMONIC
0
-10
-20
DISTORTION(dBc)
-30
-40
-50
-60
-70
-80
-90
0 100
IRE
MAX4104TOC-V
MAX4105/MAX4305 HARMONICDISTORTION vs. FREQUENCY
VOUT=2Vp-p
3R
2NDHARMONIC DHARMONIC
0
-10
HARMONICDISTORTION(dBc)
-20
-30
-40
-50
-60
-70
-80
-90
0 100
IRE
MAX4104TOC-W
MAX4104/MAX4304 HARMONICDISTORTION vs. LOAD
f=5MHz VOUT=2Vp-p
2NDHARMONIC
3RDHARMONIC
0
-10
HARMONICDISTORTION(dBc)
-20
-30
-40
-50
-60
-70
-80
-90
100k 1M 10M 100M FREQUENCY(Hz)
MAX4104TOC-X
MAX4105/MAX4305 HARMONICDISTORTION vs. LOAD
f=5MHz VOUT=2Vp-p
2NDHARMONIC
3RDHARMONIC
-100
100k 1M 10M 100M FREQUENCY(Hz)
MAX4104/MAX4304 HARMONICDISTORTION
-100
0
100 200 300 400 500 600 700 800 900 1k
LOAD()
MAX4105/MAX4305 HARMONICDISTORTION
-100
0
100 200 300 400 500 600 700 800 900 1k
LOAD()
0
-10
HARMONICDISTORTION(dBc)
-20
-30
-40
-50
-60
-70
f=5MHz
vs. OUTPUT SWING
2NDHARMONIC
0
MAX4104TOC-Y
-10
HARMONICDISTORTION(dBc)
-20
-30
-40
-50
-60
-70
f=5MHz
vs. OUTPUT SWING
2NDHARMONIC
OUTPUT SWINGvs. LOADRESISTANCE
MAX4104TOC-Z
MAX4104TOCAA
8
7
OUTPUTSWING(Vp-p)
6
5
4
3
-80
3RDHARMONIC
-80
3RDHARMONIC
-90
-100
2
-90
-100 1
0.5
1.0
1.5 2.0 2.5
3.0 3.5 4.0
0.5
1.0
1.5 2.0 2.5
3.0 3.5 4.0
0 50
100 150
200 250 300 350 400
OUTPUTSWING(Vp-p)
OUTPUTSWING(Vp-p)
LOADRESISTANCE( )
Typical Operating Characteristics (continued)
(VCC = +5V, VEE = -5V, RF = 330, RL = 100, TA = +25°C, unless otherwise noted.)
3.0
2.5
INPUTOFFSETVOLTAGE(mV)
2.0
1.5
1.0
0.5
0.0
-0.5
-1.0
-1.5
-2.0
-2.5
-3.0
INPUTOFFSET VOLTAGE vs. TEMPERATURE
INPUTOFFSET CURRENT vs. TEMPERATURE
MAX4104TOCBB
4
INPUTOFFSETCURRENT(A)
3
2
1
0
-1
-2
-3
INPUT BIASCURRENT vs. TEMPERATURE
MAX4104TOC-CC
MAX4104TOC-DD
35
INPUTBIASCURRENT(A)
34
33
32
31
30
-40
-15 10
35 60 85
-40
-15 10
35 60 85
-40
-15 10
35 60 85
MAX4104TOC-GG
TEMPERATURE(°C)
TEMPERATURE(°C)
TEMPERATURE(°C)
SUPPLY CURRENT vs. TEMPERATURE
25
24
SUPPLYCURRENT(mA)
23
22
21
20
19
18
17
16
15
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX4104TOC-EE
25
24
SUPPLYCURRENT(mA)
23
22
21
20
19
18
17
16
15
4.0
MAX4104TOC-FF
3.9
VOLTAGESWING(V)
3.8
3.7
3.6
3.5
3.4
3.3
3.2
POSITIVEOUTPUT VOLTAGESWING vs. TEMPERATURE
RL=100k | |||||
RL=100k | |||||
-40
-15 10
35 60 85
9.0 9.5 10.0 10.5 11.0
-40 -15 10 35 60 85
+50mV
IN
-50mV
TEMPERATURE(°C)
MAX4104
SMALL-SIGNAL PULSERESPONSE (AV = +1)
MAX4104TOCHH
GND
+25mV
IN
-25mV
SUPPLYVOLTAGE(V)
MAX4304
SMALL-SIGNAL PULSERESPONSE (AV = +2)
MAX4104TOCII
IN GND+10mV
-10mV
TEMPERATURE(°C)
MAX4105
SMALL-SIGNAL PULSERESPONSE (AV = +5)
MAX4104TOCJJ
GND
+50mV OUT
-50mV
GND
+50mV
OUT
-50mV
GND
+50mV
OUT
-50mV
GND
10ns/div
10ns/div
10ns/div
IN
+5mV
-5mV
MAX4305
SMALL-SIGNAL PULSERESPONSE (AV = +10)
MAX4104TOCKK
GND
+1V IN
-1V
MAX4104
LARGE-SIGNAL PULSERESPONSE (AV = +1)
MAX4104TOCLL
GND
+50mV
OUT
-50mV
GND
+1V OUT
-1V
GND
10ns/div 10ns/div
IN
+500mV
-500mV
MAX4305
LARGE-SIGNAL PULSERESPONSE (AV = +2)
MAX4104TOCMM
GND
IN
+200mV
-200mV
MAX4105
LARGE-SIGNAL PULSERESPONSE (AV = +5)
MAX4104TOCNN
GND
+1V +1V
OUT
GND
OUT
GND
-1V -1V
10ns/div 10ns/div
MAX4305
LARGE-SIGNAL PULSERESPONSE (AV = +10)
IN
+100mV
-100mV
MAX4104TOCOO
GND
+1V
OUT
GND
-1V
10ns/div
Pin Description
PIN | NAME | FUNCTION | |
SOT23-5 | SO | ||
— | 1, 5, 8 | N.C. | Not internally connected. |
4 | 2 | IN- | Amplifier Inverting Input |
3 | 3 | IN+ | Amplifier Noninverting Input |
2 | 4 | VEE | Negative Power Supply |
1 | 6 | OUT | Amplifier Output |
5 | 7 | VCC | Positive Power Supply |
Detailed Description
The MAX4104/MAX4105/MAX4304/MAX4305 are ultra- high-speed, low-noise amplifiers featuring -3dB band- widths up to 880MHz, 0.1 d B gain flatness up to 100MHz, and low differential gain and phase errors of 0.01% and 0.01°, respectively. These devices operate on dual power supplies ranging from ±3.5V to ±5.5V and require only 20mA of supply current.
The MAX4104/MAX4304/MAX4105/MAX4305 are opti-
mized for minimum closed-loop gains of +1V/V, +2V/V,
+5V/V and +10V/V (respectively) with corresponding
-3dB bandwidths of 880MHz, 730MHz, 430MHz, and 350MHz. Each device in this family features a low input voltage noise density of only 2.1nV/Hz (at 1MHz), an output current drive of ± 70mA, and spurious-free dynamic range as low as -88dBc (5MHz, RL = 100).
Applications Infor mation
Layout and Power-Supply Bypassing
The MAX4104/MAX4105/MAX4304/MAX4305 have an
extremely high bandwidth, and consequently require careful board layout, including the possible use of constant-impedance microstrip or stripline techniques.
To realize the full AC performance of these high-speed amplifiers, pay careful attention to power-supply bypassing and board layout. The PC board should have at least two layers: a signal and power layer on one side, and a large, low-impedance ground plane on the other side. The ground plane should be as free of voids as possible. With multilayer boards, locate the ground plane on a layer that incorporates no signal or
Regardless of whether or not a constant-impedance board is used, it is best to observe the following guide- lines when designing the board:
Do not use wire-wrapped boards (they are much too inductive) or breadboards (they are much too capacitive).
Do not use IC sockets. IC sockets increase reac- tances.
Keep signal lines as short and straight as possible. Do not make 90° turns; round all corners.
Observe high-frequency bypassing techniques to maintain the amplifier’s accuracy and stability.
Bear in mind that, in general, surface-mount compo- nents have shorter bodies and lower parasitic reac- tance, resulting in greatly improved high-frequency performance over through-hole components.
The bypass capacitors should include 1nF and 0.1µF ceramic surface-mount capacitors between each sup- ply pin and the ground plane, located as close to the package as possible. Optionally, place a 10µF tantalum capacitor at the power supply pins’ point of entry to the PC board to ensure the integrity of incoming supplies. The power-supply trace should lead directly from the tantalum capacitor to the VCC and VEE pins. To mini- mize parasitic inductance, keep PC traces short and use surface-mount components.
Input termination resistors and output back-termination resistors, if used, should be surface-mount types, and should be placed as close to the IC pins as possible.
DC and Noise Errors
The MAX4104/MAX4105/MAX4304/MAX4305 output
offset voltage, VOUT (Figure 1), can be calculated with the following equation:
VOUT = [VOS + (IB+ x RS) + (IB- x (RF || RG))] [1 + RF / RG]
where:
VOS = input offset voltage (in volts)
1 + RF/RG = amplifier closed-loop gain (dimensionless) IB+ = noninverting input bias current (in amps)
IB- = inverting input bias current (in amps) RG = gain-setting resistor (in ohms)
RF = feedback resistor (in ohms)
RS = source resistor at noninverting input (in ohms) The following equation represents output noise density:
power traces.
RF 2
2 2
en(OUT)
1 in x RS in x RF ||RG en
RG
RG RF FB IB- OUT VOUT IB+ IN MAX4104 RS MAX4105 MAX4304 MAX4305 |
RG
RF
RL
75
MAX4104 MAX4105 MAX4304 MAX4305
RT
75
IN+
75 CABLE
RT
75 75 CABLE
OUT
IN-
Figure 1. Output Offset Voltage Figure 2. Video Line Driver
where:
in = input current noise density (in pA/Hz) en = input voltage noise density (in nV/Hz)
The MAX4104/MAX4105/MAX4304/MAX4305 have a
very low, 2.1nV/Hz input voltage noise density and 3.1pA/Hz input current noise density.
An example of DC-error calculations, using the MAX4304 typical data and the typical operating circuit with RF = RG = 330 (RF || RG = 165) and RS = 50 gives:
V 32 x 106 50 32 x 106 165 1 x 103 1 1
very rapidly during the conversion cycle—a condition that demands an amplifier with very low output imped- ance at high frequencies to maintain measurement accuracy. The combination of high-speed, fast slew rate, low noise, and low-distortion available in the MAX4104/MAX4105/MAX4304/MAX4305 makes them ideally suited for use as buffer amplifiers in high-speed ADC applications.
Video Line Driver
The MAX4104/MAX4105/MAX4304/MAX4305 are opti-
mized to drive coaxial transmission lines when the cable is terminated at both ends, as shown in Figure 2.
OUT
To minimize reflections and maximize power transfer,
VOUT 15.8mV
Calculating total output noise in a similar manner yields the following:
select the termination resistors to match the character- istic impedance of the transmission line. Cable frequen- cy response can cause variations in the flatness of the signal.
en(OUT)
11 3.1 x 1012 x 50 2 3.1 x 1012 x 165 2 2.1 x 109 2
Driving Capacitive Loads
The MAX4104/MAX4105/MAX4304/MAX4305 provide
maximum AC performance when driving no output load
en(OUT) 4.3nV Hz
capacitance. This is the case when driving a correctly terminated transmission line (i.e., a back-terminated cable).
With a 200MHz system bandwidth, this calculates to
60.8µVRMS (approximately 365µVp-p, using the six- sigma calculation).
ADC Input Buffers Input buffer amplifiers can be a source of significant error in high-speed ADC applications. The input buffer is usually required to rapidly charge and discharge the ADC’s input, which is often capacitive. In addition, the input impedance of a high-speed ADC often changes
In most amplifier circuits, driving a large load capaci- tance increases the chance of oscillations occurring. The amplifier’s output impedance and the load capaci- tor combine to add a pole and excess phase to the loop response. If the pole’s frequency is low enough and phase margin is degraded sufficiently, oscillations may result.
A second concern when driving capacitive loads origi- nates from the amplifier’s output impedance, which
30
25
20
15
10
5
0
-5
-10
-15
-20
100k
CL=15pF
30
25
20
CL=15pF
FREQUENCY(Hz)
FREQUENCY(Hz)
CL=10pF
CL=15pF
25
20
15
10
5
0
-5
-10
-15
-20
-25
100k
1G
100M
1M 10M
CL=5pF
CL=10pF
15
10
5
0
-5
-10
-15
-20
100k
1G
100M
1M 10M
CL=5pF
CL=10pF
NORMALIZEDGAIN(dB)
GAIN(dB)
NORMALIZEDGAIN(dB)
Figure 3a. MAX4104 Frequency Response with Capacitive Load and No Isolation Resistor
FREQUENCY(Hz)
1G
100M
1M 10M
CL=5pF
Figure 3c. MAX4105 Frequency Response with Capacitive Load and No Isolation Resistor
Figure 3b. MAX4304 Frequency Response with Capacitive Load and No Isolation Resistor
FREQUENCY(Hz)
1G
100M
1M 10M
CL=5pF
CL=10pF
CL=15pF
25
20
15
10
5
0
-5
-10
-15
-20
-25
100k
NORMALIZEDGAIN(dB)
Figure 3d. MAX4305 Frequency Response with Capacitive Load and No Isolation Resistor
appears inductive at high frequencies. This inductance forms an L-C resonant circuit with the capacitive load, which causes peaking in the frequency response and degrades the amplifier’s phase margin.
The MAX4104/MAX4105/MAX4304/MAX4305 drive
capacitive loads up to 10 pF without oscillation. However, some peaking may occur in the frequency domain (Figure 3). To drive larger capacitance loads or to reduce ringing, add an isolation resistor between the amplifier’s output and the load (Figure 4).
The value of RISO depends on the circuit’s gain and the capacitive load (Figure 5). Figure 6 shows the MAX4104/MAX4105/MAX4304/MAX4305 frequency response with the isolation resistor and a capacitive
load. With higher capacitive values, bandwidth is domi- nated by the RC network formed by RISO and CL; the bandwidth of the amplifier itself is much higher. Also note that the isolation resistor forms a divider that decreases the voltage delivered to the load.
Maxim’s High-Speed Evaluation Boards The MAX4104 evaluation kit manual shows a suggest- ed layout for Maxim’s high-speed, single-amplifier eval- uation boards. This board was developed using the techniques described previously (see Layout and Power-Supply Bypassing section). The smallest avail- able surface-mount resistors were used for the feed- back and back-termination resistors to minimize the
RG RF MAX4104 MAX4105 MAX4304 IN- MAX4305 OUT RISO IN+ CL RL
|
4 3 2 CL=47pF 1 CL=68pF 0 -1 -2 CL=83pF -3 -4 -5 MAX4104/MAX4304 RISO=15 -6 100k 1M 10M 100M 1G FREQUENCY(Hz) |
OPTIMAL ISLOATIONRESISTOR( )
GAIN(dB)
Figure 4. Using an Isolation Resistor (RISO) for High Capacitive Loads
30 25 20 MAX4105/MAX4305 15 10 5 MAX4104/MAX4304 0 0 50 100 150 200 250 CAPACITIVELOAD(pF) |
Figure 5. Optimal Isolation Resistor (RISO) vs. Capacitive Load
TOPVIEW N.C. 1 MAX4104 8 N.C. MAX4105 IN- 2 7 VCC IN+ 3 6 OUT VEE 4 MAX4304 5 N.C. MAX4305 SO |
Pin Configurations (continued)
Figure 6. Frequency Responses vs. Capacitive Load with 15 Isolation Resistor
distance from the IC to these resistors, thus reducing the capacitance associated with longer lead lengths.
SMA connectors were used for best high-frequency performance. Because distances are extremely short, performance is unaffected by the fact that inputs and outputs do not match a 50 line. However, in applica- tions that require lead lengths greater than 1/4 of the wavelength of the highest frequency of interest, constant-impedance traces should be used.
Fully assembled evaluation boards are available for the MAX4104 in an 8-pin SO package.
Ordering Infor mation (continued)
PART | TEMP. RANGE | PIN- PACKAGE | SOT TOP MARK | |
MAX4105ESA | -40°C to | +85°C | 8 SO | — |
MAX4105EUK-T | -40°C to | +85°C | 5 SOT23-5 | ACCP |
MAX4304ESA | -40°C to | +85°C | 8 SO | — |
MAX4304EUK-T | -40°C to | +85°C | 5 SOT23-5 | ACCQ |
MAX4305ESA* | -40°C to | +85°C | 8 SO | — |
MAX4305EUK-T | -40°C to | +85°C | 5 SOT23-5 | ACCR |
*Future product—contact factory for availability.
Chip Infor mation
TRANSISTOR COUNT: 44 SUBSTRATE CONNECTED TO VEE
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MAX4304ESA+ MAX4104ESA+ MAX4104ESA+T MAX4104EUK+T MAX4105ESA+ MAX4105ESA+T MAX4105EUK+T MAX4304ESA MAX4304ESA+T MAX4304EUK+T MAX4304EUK-T MAX4305ESA+T MAX4305EUK+T MAX4305ESA+ MAX4105ESA MAX4105ESA-T MAX4105EUK-T MAX4304ESA-T MAX4305EUK- T MAX4304EUK+