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

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

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.


ABSOLUTE MAXIMUM RATINGS

MAX4104/MAX4105/MAX4304/MAX4305

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


MAX4104/MAX4105/MAX4304/MAX4305

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

MAX4104/MAX4105/MAX4304/MAX4305

(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


MAX4104/MAX4105/MAX4304/MAX4305

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)



MAX4104/MAX4105/MAX4304/MAX4305

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( )


MAX4104/MAX4105/MAX4304/MAX4305

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



MAX4104/MAX4105/MAX4304/MAX4305

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:

MAX4104/MAX4105/MAX4304/MAX4305

  1. Do not use wire-wrapped boards (they are much too inductive) or breadboards (they are much too capacitive).

  2. Do not use IC sockets. IC sockets increase reac- tances.

  3. Keep signal lines as short and straight as possible. Do not make 90° turns; round all corners.

  4. Observe high-frequency bypassing techniques to maintain the amplifier’s accuracy and stability.

  5. 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-

MAX4104/MAX4105/MAX4304/MAX4305

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

MAX4104/MAX4105/MAX4304/MAX4305

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)

MAX4104/MAX4105/MAX4304/MAX4305

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

Mouser Electronics


Authorized Distributor


Click to View Pricing, Inventory, Delivery & Lifecycle Information:


Maxim Integrated:

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+