LT1229CN8_技术文档

LT1229/LT1230

Dual and Quad 100MHz

Current Feedback Amplifiers

U

DESCRIPTIO

EATURE

S

F

■

100MHz Bandwidth

1000V/µs Slew Rate

Low Cost

The LT1229/LT1230 dual and quad 100MHz current feed-

back amplifiers are designed for maximum performance

in small packages. Using industry standard pinouts, the

dual is available in the 8-pin miniDIP and the 8-pin SO

package while the quad is in the 14-pin DIP and 14-pin SO.

The amplifiers are designed to operate on almost any

available supply voltage from 4V (±2V) to 30V (±15V).

30mA Output Drive Current

0.04% Differential Gain

0.1° Differential Phase

High Input Impedance: 25MΩ, 3pF

Wide Supply Range: ±2V to ±15V

Low Supply Current: 6mA Per Amplifier

Inputs Common Mode to Within 1.5V of Supplies

Outputs Swing Within 0.8V of Supplies

These current feedback amplifiers have very high input

impedance and make excellent buffer amplifiers. They

maintain their wide bandwidth for almost all closed-loop

voltage gains. The amplifiers drive over 30mA of output

current and are optimized to drive low impedance loads,

such as cables, with excellent linearity at high frequencies.

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PPLICATI

S

A

■

Video Instrumentation Amplifiers

Cable Drivers

The LT1229/LT1230 are manufactured on Linear

Technology’sproprietarycomplementarybipolarprocess.

For a single amplifier like these see the LT1227 and for

better DC accuracy see the LT1223.

RGB Amplifiers

Test Equipment Amplifiers

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O

TYPICAL APPLICATI

Loop Through Amplifier Frequency

Response

Video Loop Through Amplifier

10

R

187Ω

R

3.01k

R

750Ω

R

F2

750Ω

G2

G1

F1

0

NORMAL SIGNAL

–10

–20

–30

–

1/2

LT1229

1/2

LT1229

V

OUT

V

+

IN

V

–

3.01k

IN

+

–40

1% RESISTORS

WORST CASE CMRR = 22dB

TYPICALLY = 38dB

COMMON-MODE SIGNAL

12.1k

–50

–60

V

R

= G (V

+

– V

F2

–

)

IN

OUT

IN

10 100

1k 10k 100k 1M 10M 100M

= R

F1

F2

BNC INPUTS

R

= (G – 1) R

FREQUENCY (Hz)

G1

LT1229 • TA02

R

G – 1

HIGH INPUT RESISTANCE DOES NOT LOAD CABLE EVEN

WHEN POWER IS OFF

F2

R

=

G2

TRIM CMRR WITH R

G1

LT1229 • TA01

1

LT1229/LT1230

W W W

U

ABSOLUTE AXI U RATI GS

Supply Voltage ...................................................... ±18V

Input Current ...................................................... ±15mA

Output Short Circuit Duration (Note 1) .........Continuous

Operating Temperature Range

Storage Temperature Range ................. –65°C to 150°C

Junction Temperature

Plastic Package .............................................. 150°C

Ceramic Package ............................................ 175°C

Lead Temperature (Soldering, 10 sec.)................. 300°C

LT1229C, LT1230C ............................... 0°C to 70°C

LT1229M, LT1230M....................... –55°C to 125°C

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U

/O

PACKAGE RDER I FOR ATIO

TOP VIEW

ORDER PART

NUMBER

ORDER PART

OUT A

–IN A

+IN A

1

2

3

4

5

6

7

14 OUT D

13 –IN D

NUMBER

TOP VIEW

+

D

C

A

B

OUT A

–IN A

+IN A

1

2

3

4

8

7

6

5

V

12

11

10

9

+IN D

LT1229MJ8

LT1229CJ8

LT1229CN8

LT1229CS8

LT1230MJ

LT1230CJ

LT1230CN

LT1230CS

OUT B

–

+

V

A

–IN B

+IN B

–IN B

+IN C

–IN C

OUT C

B

–

V

J8 PACKAGE

N8 PACKAGE

OUT B

8

8-LEAD CERAMIC DIP 8-LEAD PLASTIC DIP

S8 PACKAGE

S8 PART MARKING

1229

J PACKAGE

N PACKAGE

8-LEAD PLASTIC SOIC

LT1124 • POI01

14-LEAD CERAMIC DIP 14-LEAD PLASTIC DIP

S PACKAGE

T_{J MAX}= 175°C, θ_JA= 100°C/W (J8)

14-LEAD PLASTIC SOIC LT1229 • POI02

T_{J MAX}= 175°C, θ_JA= 80°C/W (J)

T

_{J MAX}= 150°C, θ_JA= 100°C/W (N8)

T_{J MAX}= 150°C, θ_JA= 150°C/W (S8)

T

_{J MAX}= 150°C, θ_JA= 70°C/W (N)

_{J MAX}= 150°C, θ_JA= 110°C/W (S)

ELECTRICAL CHARACTERISTICS

Each Amplifier, V_CM= 0V, ±5V ≤ V_S= ±15V, pulse tested unless otherwise noted.

SYMBOL

PARAMETER

CONDITIONS

T = 25°C

MIN

TYP

MAX

UNITS

V

OS

Input Offset Voltage

±3

±10

±15

mV

A

●

Input Offset Voltage Drift

Noninverting Input Current

10

µV/°C

+

I

T = 25°C

A

±0.3

±3

±10

µA

IN

●

–

Inverting Input Current

T = 25°C

A

±10

±50

±100

µA

IN

e

Input Noise Voltage Density

f = 1kHz, R = 1k, R = 10Ω, R = 0Ω

3.2

1.4

32

nV/√Hz

pA/√Hz

n

F

G

S

+i

Noninverting Input Noise Current Density

Inverting Input Noise Current Density

Input Resistance

f = 1kHz, R = 1k, R = 10Ω, R = 10k

F G S

n

–in

f = 1kHz

R

V

= ±13V, V = ±15V

●

2

25

MΩ

IN

S

= ±3V, V = ±5V

S

C

IN

Input Capacitance

3

pF

Input Voltage Range

V = ±15V, T = 25°C

±13

±12

±3

±13.5

V

S

A

●

V = ±5V, T = 25°C

±3.5

S

A

±2

CMRR

Common-Mode Rejection Ratio

V = ±15V, V = ±13V, T = 25°C

55

69

dB

S

CM

A

V = ±15V, V = ±12V

●

S

CM

V = ±5V, V = ±3V, T = 25°C

S

CM

A

V = ±5V, V = ±2V

S

CM

2

LT1229/LT1230

ELECTRICAL CHARACTERISTICS

Each Amplifier, V_CM= 0V, ±5V ≤ V_S= ±15V, pulse tested unless otherwise noted.

SYMBOL

PARAMETER

CONDITIONS

V = ±15V, V = ±13V, T = 25°C

MIN

TYP

MAX

UNITS

Inverting Input Current

Common-Mode Rejection

2.5

10

µA/V

S

CM

A

V = ±15V, V = ±12V

●

S

CM

V = ±5V, V = ±3V, T = 25°C

2.5

80

S

CM

A

V = ±5V, V = ±2V

S

CM

PSRR

Power Supply Rejection Ratio

V = ±2V to ±15V, T = 25°C

60

dB

S

A

V = ±3V to ±15V

S

●

Noninverting Input Current

Power Supply Rejection

V = ±2V to ±15V, T = 25°C

10

50

nA/V

S

A

V = ±3V to ±15V

S

Inverting Input Current

Power Supply Rejection

V = ±2V to ±15V, T = 25°C

0.1

5

µA/V

S

A

V = ±3V to ±15V

S

A

V

Large-Signal Voltage Gain, (Note 2)

V = ±15V, V

= ±10V, R = 1k

●

55

65

dB

S

OUT

L

V = ±5V, V

= ±2V, R = 150Ω

S

OUT

L

R

OL

Transresistance, ∆V /∆I , (Note 2)

V = ±15V, V

= ±10V, R = 1k

●

100

200

kΩ

OUT IN–

S

OUT

L

V = ±5V, V

= ±2V, R = 150Ω

S

OUT

L

V

OUT

Maximum Output Voltage Swing, (Note 2) V = ±15V, R = 400Ω, T = 25°C

±12

±10

±3

±13.5

V

S

L

A

●

V = ±5V, R = 150Ω, T = 25°C

±3.7

S

L

A

±2.5

I

Maximum Output Current

Supply Current, (Note 3)

R = 0Ω, T = 25°C

30

65

6

125

mA

OUT

S

L

A

V

= 0V, Each Amplifier, T = 25°C

9.5

11

mA

OUT

A

●

SR

Slew Rate, (Notes 4 and 6)

Slew Rate

T = 25°C

300

700

2500

10

V/µs

ns

A

V = ±15V, R = 750Ω, R = 750Ω, R = 400Ω

S

F

G

L

t

Rise Time, (Notes 5 and 6)

Small-Signal Bandwidth

Small-Signal Rise Time

Propagation Delay

T = 25°C

A

20

r

BW

V = ±15V, R = 750Ω, R = 750Ω, R = 100Ω

S

100

3.5

MHz

ns

F

G

L

t

V = ±15V, R = 750Ω, R = 750Ω, R = 100Ω

S F G L

r

V = ±15V, R = 750Ω, R = 750Ω, R = 100Ω

S

3.5

ns

F

G

L

Small-Signal Overshoot

Settling Time

V = ±15V, R = 750Ω, R = 750Ω, R = 100Ω

15

%

S

F

G

L

t

0.1%, V

= 10V, R =1k, R = 1k, R =1k

45

ns

s

OUT

F

G

L

Differential Gain, (Note 7)

Differential Phase, (Note 7)

Differential Gain, (Note 7)

Differential Phase, (Note 7)

V = ±15V, R = 750Ω, R = 750Ω, R = 1k

0.01

0.04

0.1

%

S

F

G

L

V = ±15V, R = 750Ω, R = 750Ω, R = 1k

Deg

%

S

F

G

L

V = ±15V, R = 750Ω, R = 750Ω, R = 150Ω

S

F

G

L

V = ±15V, R = 750Ω, R = 750Ω, R = 150Ω

Deg

S

F

G

L

The

range.

●

denotes specifications which apply over the operating temperature

slew rate is much higher when the input is overdriven and when the

amplifier is operated inverting, see the applications section.

Note 1: A heat sink may be required depending on the power supply

voltage and how many amplifiers are shorted.

Note 5: Rise time is measured from 10% to 90% on a ±500mV output

signal while operating on ±15V supplies with R = 1k, R = 110Ω and R =

F

G

L

100Ω. This condition is not the fastest possible, however, it does

guarantee the internal capacitances are correct and it makes automatic

testing practical.

Note 2: The power tests done on ±15V supplies are done on only one

amplifier at a time to prevent excessive junction temperatures when testing

at maximum operating temperature.

Note 6: AC parameters are 100% tested on the ceramic and plastic DIP

packaged parts (J and N suffix) and are sample tested on every lot of the

SO packaged parts (S suffix).

Note 3: The supply current of the LT1229/LT1230 has a negative

temperature coefficient. For more information see the application

information section.

Note 7: NTSC composite video with an output level of 2V .

Note 4: Slew rate is measured at ±5V on a ±10V output signal while

P

operating on ±15V supplies with R = 1k, R = 110Ω and R = 400Ω. The

F

G

L

3

LT1229/LT1230

TYPICAL PERFOR A CE CHARACTERISTICS

U W

Voltage Gain and Phase vs

Frequency, Gain = 6dB

–3dB Bandwidth vs Supply

Voltage, Gain = 2, R_L= 1k

Voltage, Gain = 2, R_L= 100Ω

8

7

6

0

180

160

140

180

160

140

PHASE

PEAKING ≤ 0.5dB

PEAKING ≤ 5dB

45

90

R

= 500Ω

F

GAIN

R = 500Ω

R

= 750Ω

F

5

4

135

180

120

100

80

60

40

20

0

120

100

80

60

40

20

0

R = 750Ω

F

3

2

1

225

R = 1k

F

PEAKING ≤ 0.5dB

PEAKING ≤ 5dB

V

= ±15V

S

L

F

0

–1

–2

R

= 2k

R

= 1k

F

R = 2k

F

R

= 100Ω

R = 750Ω

0

2

4

6

8

10 12 14 16 18

0.1

1

10

100

0

2

4

6

8

10 12 14 16 18

SUPPLY VOLTAGE (±V)

FREQUENCY (MHz)

SUPPLY VOLTAGE (±V)

LT1229 • TPC01

LT1229 • TPC02

LT1229 • TPC03

Voltage Gain and Phase vs

Frequency, Gain = 20dB

–3dB Bandwidth vs Supply

Voltage, Gain = 10, R_L= 100Ω

–3dB Bandwidth vs Supply

Voltage, Gain = 10, R_L= 1k

22

21

20

0

180

160

140

180

160

140

PHASE

PEAKING ≤ 0.5dB

PEAKING ≤ 5dB

PEAKING ≤ 0.5dB

PEAKING ≤ 5dB

45

90

GAIN

19

18

135

180

120

100

80

60

40

20

0

120

100

80

60

40

20

0

R

= 250Ω

R = 500Ω

F

R = 250Ω

F

17

16

15

225

R = 500Ω

F

R

= 750Ω

F

R = 750Ω

F

R = 1k

F

R = 1k

F

V

= ±15V

S

L

F

14

13

12

R

= 100Ω

R = 2k

F

R = 2k

F

R = 750Ω

0.1

1

10

100

0

2

4

6

8

10 12 14 16 18

0

2

4

6

8

10 12 14 16 18

FREQUENCY (MHz)

SUPPLY VOLTAGE (±V)

LT1229 • TPC04

LT1229 • TPC05

LT1229 • TPC06

Voltage Gain and Phase vs

Frequency, Gain = 40dB

–3dB Bandwidth vs Supply

Voltage, Gain = 100, R_L= 100Ω

–3dB Bandwidth vs Supply

Voltage, Gain = 100, R_L= 1kΩ

42

41

40

0

18

16

14

18

16

14

PHASE

45

90

R

= 500Ω

GAIN

F

39

38

135

180

12

10

8

12

10

8

R = 500Ω

F

R

= 1k

F

37

36

35

225

R = 1k

F

R

= 2k

F

6

R = 2k

F

4

V

= ±15V

34

33

32

S

L

F

R

= 100Ω

2

R = 750Ω

0

0.1

1

10

100

0

2

4

6

8

10 12 14 16 18

0

2

4

6

8

10 12 14 16 18

FREQUENCY (MHz)

SUPPLY VOLTAGE (±V)

LT1229 • TPC07

LT1229 • TPC08

LT1229 • TPC09

4

LT1229/LT1230

U W

TYPICAL PERFOR A CE CHARACTERISTICS

Maximum Capacitance Load vs

Feedback Resistor

Total Harmonic Distortion vs

Frequency

2nd and 3rd Harmonic

Distortion vs Frequency

0.10

10000

1000

–20

–30

V

= ±15V

P-P

= 100Ω

S

O

L

V

R

= ±15V

= 400Ω

S

L

F

= 2V

R

V

= ±5V

= R = 750Ω

S

G

R = 750Ω

A

F

= 10dB

2ND

V

–40

–50

–60

–70

V

= ±15V

S

0.01

100

10

1

V

= 7V

RMS

3RD

O

= 1V

RMS

R

= 1k

L

PEAKING ≤ 5dB

GAIN = 2

0.001

10

100

1k

FREQUENCY (Hz)

10k

100k

0

1

2

3

1

10

FREQUENCY (MHz)

100

FEEDBACK RESISTOR (kΩ)

LT1229 • TPC11

LT1229 • TPC10

LT1229 • TPC12

Input Common-Mode Limit vs

Temperature

Output Saturation Voltage vs

Temperature

Output Short-Circuit Current vs

Junction Temperature

+

70

60

50

40

30

V

–0.5

–1.0

–1.5

–2.0

–0.5

–1.0

+

V

= 2V TO 18V

R

= ∞

L

±2V ≤ V ≤ ±18V

S

2.0

1.5

1.0

0.5

–

= –2V TO –18V

1.0

0.5

–

V

–50 –25

0

25 50 75 100 125 150 175

–50 –25

0

25

50

75 100 125

–50 –25

0

25

50

75 100 125

TEMPERATURE (°C)

LT1229 • TPC15

LT1229 • TPC13

LT1229 • TPC14

Spot Noise Voltage and Current vs

Frequency

Power Supply Rejection vs

Frequency

Output Impedance vs

Frequency

100

10

1

80

60

100

10

V

= ±15V

S

V

R

= ±15V

S

L

F

= 100Ω

–i

n

= R = 750Ω

G

POSITIVE

1.0

R

= R = 2k

G

F

40

20

0

R

= R = 750Ω

G

F

0.1

0.01

NEGATIVE

e

n

+i

n

0.001

10k

100k

1M

10M

100M

10

100

1k

FREQUENCY (Hz)

10k

100k

10k

100k

1M

FREQUENCY (Hz)

10M

100M

FREQUENCY (Hz)

LT1229 • TPC16

LT1229 • TPC17

LT1229 • TPC18

5

LT1229/LT1230

TYPICAL PERFOR A CE CHARACTERISTICS

U W

Settling Time to 10mV vs

Output Step

Settling Time to 1mV vs

Output Step

Supply Current vs Supply Voltage

10

9

10

8

10

8

NONINVERTING

INVERTING

NONINVERTING

8

6

–55°C

INVERTING

7

4

25°C

6

2

V

= ±15V

G

V

= ±15V

G

S

F

S

F

5

0

125°C

R

= R = 1k

R = R = 1k

4

3

2

1

0

–2

–4

–2

–4

175°C

INVERTING

–6

NONINVERTING

–8

NONINVERTING

20

INVERTING

60 80

–10

0

2

4

6

8

10 12 14 16 18

0

40

100

0

4

8

12

16

20

SUPPLY VOLTAGE (±V)

SETTLING TIME (ns)

SETTLING TIME (µs)

LT1229 • TPC21

LT1229 • TPC19

LT1229 • TPC20

W

SI PLIFIED SCHE ATIC

One Amplifier

+

V

+IN

–IN

V

OUT

–

V

LT1229 • TA03

6

LT1229/LT1230

O U

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PPLICATI

A

S I FOR ATIO

The LT1229/LT1230 are very fast dual and quad current

feedback amplifiers. Because they are current feedback

amplifiers, theymaintaintheirwidebandwidthoverawide

range of voltage gains. These amplifiers are designed to

drive low impedance loads such as cables with excellent

linearity at high frequencies.

limited by the gain bandwidth product of about 1GHz. The

curves show that the bandwidth at a closed-loop gain of

100 is 10MHz, only one tenth what it is at a gain of two.

Capacitance on the Inverting Input

Current feedback amplifiers want resistive feedback from

the output to the inverting input for stable operation. Take

care to minimize the stray capacitance between the output

and the inverting input. Capacitance on the inverting input

to ground will cause peaking in the frequency response

(and overshoot in the transient response), but it does not

degrade the stability of the amplifier. The amount of

capacitance that is necessary to cause peaking is a func-

tion of the closed-loop gain taken. The higher the gain, the

more capacitance is required to cause peaking. We can

add capacitance from the inverting input to ground to

increase the bandwidth in high gain applications. For

example,inthisgainof100application,thebandwidthcan

be increased from 10MHz to 17MHz by adding a 2200pF

capacitor.

Feedback Resistor Selection

The small-signal bandwidth of the LT1229/LT1230 is set

bytheexternalfeedbackresistorsandtheinternaljunction

capacitors. As a result, the bandwidth is a function of the

supply voltage, the value of the feedback resistor, the

closed-loop gain and load resistor. The characteristic

curves of Bandwidth versus Supply Voltage are done with

aheavyload(100Ω)andalightload(1k)toshowtheeffect

of loading. These graphs also show the family of curves

that result from various values of the feedback resistor.

These curves use a solid line when the response has less

than 0.5dB of peaking and a dashed line when the re-

sponse has 0.5dB to 5dB of peaking. The curves stop

where the response has more than 5dB of peaking.

+

V

IN

1/2

Small-Signal Rise Time with

R_F= R_G= 750Ω, V_S= ±15V, and R_L= 100Ω

V

OUT

LT1229

–

R

F

510Ω

R

5.1Ω

G

C

G

LT1229 • TA05

Boosting Bandwidth of High Gain Amplifier with

LT1229 • TA04

Capacitance on Inverting Input

49

At a gain of two, on ±15V supplies with a 750Ω feedback

resistor, the bandwidth into a light load is over 160MHz

without peaking, but into a heavy load the bandwidth

reduces to 100MHz. The loading has so much effect

because there is a mild resonance in the output stage that

enhances the bandwidth at light loads but has its Q

reduced by the heavy load. This enhancement is only

usefulatlowgainsettings;atagainoftenitdoesnot boost

the bandwidth. At unity gain, the enhancement is so

effective the value of the feedback resistor has very little

effect. At very high closed-loop gains, the bandwidth is

46

C

= 4700pF

G

43

40

37

34

31

28

25

22

19

C

= 2200pF

G

C

= 0

G

1

10

FREQUENCY (MHz)

100

LT1229 • TA06

7

LT1229/LT1230

O U

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PPLICATI

A

S I FOR ATIO

Capacitive Loads

amplifier at 150°C is less than 7mA and typically is only

4.5mA. The power in the IC due to the load is a function of

the output voltage, the supply voltage and load resistance.

The worst case occurs when the output voltage is at half

supply, if it can go that far, or its maximum value if it

cannot reach half supply.

The LT1229/LT1230 can drive capacitive loads directly

when the proper value of feedback resistor is used. The

graph Maximum Capacitive Load vs Feedback Resistor

should be used to select the appropriate value. The value

shown is for 5dB peaking when driving a 1k load at a gain

of 2. This is a worst case condition; the amplifier is more

stable at higher gains and driving heavier loads. Alterna-

tively, a small resistor (10Ω to 20Ω) can be put in series

with the output to isolate the capacitive load from the

amplifier output. This has the advantage that the amplifier

bandwidth is only reduced when the capacitive load is

present, and the disadvantage that the gain is a function of

the load resistance.

For example, let’s calculate the worst case power dissipa-

tioninavideocabledriveroperatingon±12Vsuppliesthat

delivers a maximum of 2V into 150Ω.

V

O MAX

(

)

P

= 2V I

+ V – V

d MAX

S S MAX

S

O MAX

(

)

(

)

(

)

(

)

R

L

2V

P

= 2 × 12V × 7mA + 12V – 2V ×

(

)

d MAX

(

150Ω

= 0.168 + 0.133 = 0.301W per Amp

Power Supplies

Now if that is the dual LT1229, the total power in the

package is twice that, or 0.602W. We now must calcu-

late how much the die temperature will rise above the

ambient. The total power dissipation times the thermal

resistance of the package gives the amount of tempera-

ture rise. For the above example, if we use the SO8

surface mount package, the thermal resistance is

150°C/W junction to ambient in still air.

The LT1229/LT1230 amplifiers will operate from single or

split supplies from ±2V (4V total) to ±15V (30V total). It is

not necessary to use equal value split supplies, however,

the offset voltage and inverting input bias current will

change. The offset voltage changes about 350µV per volt

of supply mismatch, the inverting bias current changes

about 2.5µA per volt of supply mismatch.

Temperature Rise = P_{d (MAX)}R_θJA= 0.602W ×

150°C/W = 90.3°C

Power Dissipation

The LT1229/LT1230 amplifiers combine high speed and

large output current drive into very small packages. Be-

causetheseamplifiersworkoveraverywidesupplyrange,

itispossibletoexceedthemaximumjunctiontemperature

under certain conditions. To ensure that the LT1229 and

LT1230 remain within their absolute maximum ratings,

we must calculate the worst case power dissipation,

define the maximum ambient temperature, select the

appropriate package and then calculate the maximum

junction temperature.

The maximum junction temperature allowed in the plastic

package is 150°C. Therefore, the maximum ambient al-

lowed is the maximum junction temperature less the

temperature rise.

Maximum Ambient = 150°C – 90.3°C = 59.7°C

Note that this is less than the maximum of 70°C that is

specified in the absolute maximum data listing. If we must

use this package at the maximum ambient we must lower

the supply voltage or reduce the output swing.

The worst case amplifier power dissipation is the total of

the quiescent current times the total power supply voltage

plus the power in the IC due to the load. The quiescent

supply current of the LT1229/LT1230 has a strong nega-

tive temperature coefficient. The supply current of each

As a guideline to help in the selection of the LT1229/

LT1230 the following table describes the maximum sup-

ply voltage that can be used with each part in cable driving

applications.

8

LT1229/LT1230

O U

W

U

PPLICATI

A

S I FOR ATIO

Large-Signal Response, A_V= 2, R_F= R_G= 750Ω

Assumptions:

1. The maximum ambient is 70°C for the commercial

parts (C suffix) and 125°C for the full temperature

parts (M suffix).

2. The load is a double-terminated video cable, 150Ω.

3. The maximum output voltage is 2V (peak or DC).

4. The thermal resistance of each package:

J8 is 100°C/W

N8 is 100°C/W

S8 is 150°C/W

J is 80°/W

N is 70°/W

S is 110°/W

LT1229 • TA07

Larger feedback resistors will reduce the slew rate as will

lower supply voltages, similar to the way the bandwidth is

reduced.

Maximum Supply Voltage for 75Ω Cable Driving Applications at

Maximum Ambient Temperature

PART

PACKAGE

MAX POWER AT T

MAX SUPPLY

V < ±10.1

A

Large-Signal Response, A_V= 10, R_F= 1k, R_G= 110Ω

LT1229MJ8

LT1229CJ8

LT1229CN8

LT1229CS8

Ceramic DIP

Plastic DIP

Plastic SO8

0.500W @ 125°C

1.050W @ 70°C

0.800W @ 70°C

0.533W @ 70°C

S

V < ±18.0

S

V < ±15.6

S

V < ±10.6

S

LT1230MJ

LT1230CJ

LT1230CN

LT1230CS

Ceramic DIP

Plastic DIP

0.625W @ 125°C

1.313W @ 70°C

1.143W @ 70°C

0.727W @ 70°C

V < ±6.6

S

V < ±13.0

S

V < ±11.4

S

Plastic SO14

V < ±7.6

S

Slew Rate

The slew rate of a current feedback amplifier is not

independent of the amplifier gain the way it is in a tradi-

tional op amp. This is because the input stage and the

output stage both have slew rate limitations. The input

stage of the LT1229/LT1230 amplifiers slew at about

100V/µs before they become nonlinear. Faster input sig-

nals will turn on the normally reverse-biased emitters on

the input transistors and enhance the slew rate signifi-

cantly. This enhanced slew rate can be as much as

2500V/µs.

LT1229 • TA08

Settling Time

The characteristic curves show that the LT1229/LT1230

amplifiers settle to within 10mV of final value in 40ns to

55ns for any output step up to 10V. The curve of settling

to 1mV of final value shows that there is a slower thermal

contribution up to 20µs. The thermal settling component

comes from the output and the input stage. The output

contributes just under 1mV per volt of output change and

the input contributes 300µV per volt of input change.

Fortunately, the input thermal tends to cancel the output

thermal. For this reason the noninverting gain of two

configurationssettlesfasterthantheinvertinggainofone.

The output slew rate is set by the value of the feedback

resistors and the internal capacitance. At a gain of ten with

a 1k feedback resistor and ±15V supplies, the output slew

rate is typically 700V/µs and –1000V/µs. There

is no input stage enhancement because of the high gain.

9

LT1229/LT1230

O U

W

U

PPLICATI

A

S I FOR ATIO

Crosstalk and Cascaded Amplifiers

The high frequency crosstalk between amplifiers is

caused by magnetic coupling between the internal wire

bonds that connect the IC chip to the package lead frame.

The amount of crosstalk is inversely proportional to the

load resistor the amplifier is driving, with no load (just

the feedback resistor) the crosstalk improves 18dB. The

curve shows the crosstalk of the LT1229 amplifier B

output (pin 7) to the input of amplifier A. The crosstalk

from amplifier A’s output (pin 1) to amplifier B is about

10dB better. The crosstalk between all of the LT1230

amplifiers is as shown. The LT1230 amplifiers that are

separated by the supplies are a few dB better.

The amplifiers in the LT1229/LT1230 do not share any

common circuitry. The only thing the amplifiers share is

the supplies. As a result, the crosstalk between amplifiers

is very low. In a good breadboard or with a good PC board

layout the crosstalk from the output of one amplifier to the

input of another will be over 100dB down, up to 100kHz

and 65dB down at 10MHz. The following curve shows

the crosstalk from the output of one amplifier to the

input of another.

Amplifier Crosstalk vs Frequency

When cascading amplifiers the crosstalk will limit the

amount of high frequency gain that is available because

the crosstalk signal is out of phase with the input signal.

This will often show up as unusual frequency response.

For example: cascading the two amplifiers in the LT1229,

each set up with 20dB of gain and a –3dB bandwidth of

65MHz into 100Ω will result in 40dB of gain, BUT the

responsewillstarttodropatabout10MHzandthenflatten

out from 20MHz to 30MHz at about 0.5dB down. This is

due to the crosstalk back to the input of the first amplifier.

120

V

A

R

= ±15V

= 10

= 50Ω

= 100Ω

S

V

S

L

110

100

90

80

70

60

50

10 100

1k 10k 100k 1M 10M 100M

ForbestresultswhencascadingamplifiersusetheLT1229

and drive amplifier B and follow it with amplifier A.

FREQUENCY (Hz)

LT1229 • TA12

U

O

TYPICAL APPLICATI S

Single 5V Supply Cable Driver for Composite Video

(the sync pulses). R4, R5 and R6 set the amplifier up with

a gain of two and bias the output so the bottom of the sync

pulses are at 1.1V. The maximum input then drives the

output to 3.9V.

This circuit amplifies standard 1V peak composite video

input (1.4V_P-P) by two and drives an AC coupled, doubly

terminated cable. In order for the output to swing

2.8V_P-Pon a single 5V supply, it must be biased accu-

rately. The average DC level of the composite input is a

function of the luminance signal. This will cause problems

if we AC couple the input signal into the amplifier because

a rapid change in luminance will drive the output into the

rails. To prevent this we must establish the DC level at the

input and operate the amplifier with DC gain.

5V

R1

3k

R4

1.5k

C3

47µF

2N3904

C2

1µF

R2

2k

C1

1µF

+

V

OUT

C4

R7

75Ω

+

1000µF

V

+

IN

1/2

LT1229

R3

150k

R6

510Ω

–

R8

10k

The transistor’s base is biased by R1 and R2 at 2V. The

emitter of the transistor clamps the noninverting input of

the amplifier to 1.4V at the most negative part of the input

R5

750Ω

LT1229 • TA11

10

LT1229/LT1230

U

O

TYPICAL APPLICATI S

Single Supply AC Coupled Amplifiers

Noninverting

Inverting

5V

4.7µF

5V

+

4.7µF

+

10kΩ

10k

0.1µF

+

1/2

+

V

IN

V

OUT

0.1µF

LT1229

–

1/2

LT1229

V

OUT

–

4.7µF

R

51Ω

510Ω

S

4.7µF

V

51Ω

= 11

510Ω

IN

510Ω

A

=

10

V

R

+ 51Ω

A

S

V

BW = 600Hz TO 50MHz

LT1229 • TA09

LT1229 • TA10

BW = 600Hz TO 50MHz

U

PACKAGE DESCRIPTIO Dimensions in inches (millimeters) unless otherwise noted.

0.405

(10.287)

MAX

0.005

(0.127)

MIN

0.200

(5.080)

MAX

0.290 – 0.320

(7.366 – 8.128)

6

5

4

8

7

0.015 – 0.060

(0.381 – 1.524)

J8 Package

8-Lead Ceramic DIP

0.025

(0.635)

RAD TYP

0.220 – 0.310

(5.588 – 7.874)

0.008 – 0.018

(0.203 – 0.460)

0° – 15°

1

2

3

0.055

(1.397)

MAX

0.038 – 0.068

(0.965 – 1.727)

0.385 ± 0.025

(9.779 ± 0.635)

0.125

3.175

MIN

0.100 ± 0.010

0.014 – 0.026

(2.540 ± 0.254)

(0.360 – 0.660)

J8 0392

0.400

(10.160)

MAX

0.130 ± 0.005

(3.302 ± 0.127)

0.300 – 0.320

(7.620 – 8.128)

0.045 – 0.065

(1.143 – 1.651)

8

7

6

5

4

N8 Package

8-Lead Plastic DIP

0.065

(1.651)

TYP

0.250 ± 0.010

(6.350 ± 0.254)

0.009 – 0.015

(0.229 – 0.381)

0.125

(3.175)

MIN

0.020

(0.508)

MIN

+0.025

–0.015

0.045 ± 0.015

(1.143 ± 0.381)

1

2

3

0.325

+0.635

8.255

(

)

–0.381

0.100 ± 0.010

(2.540 ± 0.254)

0.018 ± 0.003

(0.457 ± 0.076)

N8 0392

0.189 – 0.197

(4.801 – 5.004)

0.010 – 0.020

(0.254 – 0.508)

7

5

8

6

× 45°

0.053 – 0.069

(1.346 – 1.752)

0.004 – 0.010

(0.101 – 0.254)

0.008 – 0.010

(0.203 – 0.254)

S8 Package

8-Lead Plastic SOIC

0.228 – 0.244

(5.791 – 6.197)

0.150 – 0.157

(3.810 – 3.988)

0.016 – 0.050

0.406 – 1.270

0.050

(1.270)

BSC

0.014 – 0.019

(0.355 – 0.483)

0°– 8° TYP

SO8 0392

1

2

3

4

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.

However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-

tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.

11

LT1229/LT1230

U

PACKAGE DESCRIPTIO

Dimensions in inches (millimeters) unless otherwise noted.

J Package

14-Lead Ceramic DIP

0.785

(19.939)

MAX

0.005

(0.127)

MIN

0.200

(5.080)

MAX

0.290 – 0.320

(7.366 – 8.128)

14

13

12

11

10

9

8

0.015 – 0.060

(0.381 – 1.524)

0.220 – 0.310

0.025

(5.588 – 7.874)

(0.635)

RAD TYP

0.008 – 0.018

0° – 15°

(0.203 – 0.460)

2

3

4

5

6

1

7

0.098

(2.489)

MAX

0.385 ± 0.025

0.038 – 0.068

0.100 ± 0.010

(2.540 ± 0.254)

0.125

(3.175)

MIN

(9.779 ± 0.635)

(0.965 – 1.727)

0.014 – 0.026

(0.360 – 0.660)

J14 0392

N Package

14-Lead Plastic DIP

0.770

(19.558)

MAX

0.065

(1.651)

TYP

0.300 – 0.325

(7.620 – 8.255)

0.045 – 0.065

(1.143 – 1.651)

0.015

(0.380)

MIN

14

13

12

11

10

9

8

0.130 ± 0.005

(3.302 ± 0.127)

0.260 ± 0.010

(6.604 ± 0.254)

0.009 – 0.015

(0.229 – 0.381)

+0.025

1

2

3

5

6

7

4

0.325

–0.015

0.075 ± 0.015

(1.905 ± 0.381)

0.018 ± 0.003

(0.457 ± 0.076)

0.125

(3.175)

MIN

+0.635

8.255

(

)

–0.381

0.100 ± 0.010

(2.540 ± 0.254)

N14 0392

S Package

14-Lead Plastic SOIC

0.337 – 0.344

(8.560 – 8.738)

0.010 – 0.020

(0.254 – 0.508)

14

13

12

11

10

9

8

× 45°

0.053 – 0.069

(1.346 – 1.752)

0.008 – 0.010

(0.203 – 0.254)

0.004 – 0.010

(0.101 – 0.254)

0.228 – 0.244

0.150 – 0.157

(5.791 – 6.197)

(3.810 – 3.988)

0° – 8° TYP

0.050

(1.270)

TYP

0.016 – 0.050

0.406 – 1.270

0.014 – 0.019

(0.355 – 0.483)

SO14 0392

1

2

3

4

5

6

7

LT/GP 1092 5K REV A

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7487

12

●

LINEAR TECHNOLOGY CORPORATION 1992

(408) 432-1900 FAX: (408) 434-0507 TELEX: 499-3977


型号：	LT1229CN8
厂家：	Linear
描述：	Dual and Quad 100MHz Current Feedback Amplifiers 双路和四路100MHz的电流反馈放大器运算放大器放大器电路光电二极管
文件：	总12页 (文件大小：293K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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