Datasheet LT1207 Datasheet (Linear Technology)

LT1207

Dual 250mA/60MHz

Current Feedback Amplifier

EATU

F

■

250mA Minimum Output Drive Current

■

60MHz Bandwidth, AV = 2, RL = 100Ω

■

900V/µs Slew Rate, AV = 2, RL = 50Ω

■

0.02% Differential Gain, AV = 2, RL = 30Ω

■

0.17° Differential Phase, AV = 2, RL = 30Ω

■

High Input Impedance: 10MΩ

■

Shutdown Mode: IS < 200µA per Amplifier

■

Stable with CL = 10,000pF

RE

S

U

APPLICATIO S

■

ADSL/HDSL Drivers

■

Video Amplifiers

■

Cable Drivers

■

RGB Amplifiers

■

Test Equipment Amplifiers

■

Buffers

DUESCRIPTIO

The LT®1207 is a dual version of the LT1206 high speed
current feedback amplifier. Like the LT1206, each CFA in
the dual has excellent video characteristics: 60MHz band­width, 250mA minimum output drive current, 400V/µs
minimum slew rate, low differential gain (0.02% typ) and
low differential phase (0.17° typ). The LT1207 includes a
pin for an optional compensation network which stabi­lizes the amplifier for heavy capacitive loads. Both ampli­fiers have thermal and current limit circuits which protect
against fault conditions. These capabilities make the LT1207
well suited for driving difficult loads such as cables in video
or digital communication systems.

Operation is fully specified from ±5V to ±15V supplies.
Supply current is typically 20mA per amplifier. Two
micropower shutdown controls place each amplifier in a
high impedance low current mode, dropping supply
current to 200µA per amplifier. For reduced bandwidth
applications, supply current can be lowered by adding a
resistor in series with the Shutdown pin.

TYPICAL APPLICATION

V

IN

15k

15k

U

SHDN A

240Ω

SHDN B

5V

+

1/2 LT1207

–

720Ω

720Ω
720Ω

–

1/2 LT1207

+

–5V

The LT1207 is manufactured on Linear Technology's
complementary bipolar process and is available in a low
thermal resistance 16-lead SO package.

, LTC and LT are registered trademarks of Linear Technology Corporation.

HDSL Driver

0.1µF*


0.1µF*


62Ω

62Ω

+

2.2µF**


2.2µF**

+



L1

*

CERAMIC

**

TANTALUM
L1 =TRANSPOWER SMPT–308 
 OR SIMILAR DEVICE

1207 • TA01

1

LT1207

WU

U

PACKAGE

/

O

RDER I FOR ATIO

TOP VIEW

S PACKAGE

16-LEAD PLASTIC SO

1
2
3
4
5
6
7
8

16
15
14
13
12
11
10

9

V+
–IN A
+IN A

SHDN A

–IN B
+IN B

SHDN B

V

+

V+
OUT A
V

–

A
COMP A
OUT B
V

–

B
COMP B
V

+





W

O

A

LUTEXI T

S

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

Input Current per Amplifier ............................... ±15mA

A

WUW

ARB

U
G

I

S

ORDER PART

NUMBER

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

Specified Temperature Range (Note 2)...... 0°C to 70°C

LT1207CS

Operating Temperature Range ............... –40°C to 85°C

Junction Temperature......................................... 150°C

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

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

θJA = 40°C/W (NOTE 3)

Consult factory for Industrial and Military grade parts.

ELECTRICAL CHARACTERISTICS

VCM = 0, ±5V ≤ VS ≤ ±15V, pulse tested, V

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

OS

+

I

IN

–

I

IN

e

n

+i

n

–i

n

R

IN

C

IN

CMRR Common Mode Rejection Ratio VS = ±15V, VCM = ±12V ● 55 62 dB

PSRR Power Supply Rejection Ratio VS = ±5V to ±15V ● 60 77 dB

Input Offset Voltage TA = 25°C ±3 ±10 mV

Input Offset Voltage Drift ● 10 µV/°C
Noninverting Input Current TA = 25°C ±2 ±5 µA

Inverting Input Current TA = 25°C ±10 ±60 µA

Input Noise Voltage Density f = 10kHz, RF = 1k, RG = 10Ω, RS = 0Ω 3.6 nV/√Hz
Input Noise Current Density f = 10kHz, RF = 1k, RG = 10Ω, RS = 10k 2 pA/√Hz
Input Noise Current Density f = 10kHz, RF = 1k, RG = 10Ω, RS = 10k 30 pA/√Hz
Input Resistance VIN = ±12V, VS = ±15V ● 1.5 10 MΩ

Input Capacitance VS = ±15V 2 pF
Input Voltage Range VS = ±15V ● ±12 ±13.5 V

Inverting Input Current VS = ±15V, VCM = ±12V ● 0.1 10 µA/V
Common Mode Rejection V

= 0V, V

SHDN A

VIN = ±2V, VS = ±5V ● 0.5 5 MΩ

VS = ±5V ● ±2 ±3.5 V

V

= ±5V, VCM = ±2V ● 50 60 dB

S

= ±5V, VCM = ±2V ● 0.1 10 µA/V

S

= 0V, unless otherwise noted.

SHDN B

● ±15 mV

● ±20 µA

● ±100 µA

2

LT1207

ELECTRICAL CHARACTERISTICS

VCM = 0, ±5V ≤ VS ≤ ±15V, pulse tested, V

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

Noninverting Input Current VS = ±5V to ±15V ● 30 500 nA/V
Power Supply Rejection

Inverting Input Current VS = ±5V to ±15V ● 0.7 5 µA/V
Power Supply Rejection

A

V

R

OL

V

OUT

I

OUT

I

S

SR Slew Rate (Note 5) AV = 2, TA = 25°C 400 900 V/µs

BW Small-Signal Bandwidth VS = ±15V, Peaking ≤ 0.5dB 60 MHz

Large-Signal Voltage Gain VS = ±15V, V

Transresistance, ∆V

OUT

/∆I

–

IN

Maximum Output Voltage Swing VS = ±15V, RL = 50Ω, TA = 25°C ±11.5 ±12.5 V

Maximum Output Current RL = 1Ω ● 250 500 1200 mA
Supply Current per Amplifier VS = ±15V, V

Supply Current per Amplifier, VS = ±15V, TA = 25°C1217mA
R

= 51k (Note 4)

SHDN

Positive Supply Current VS = ±15V, V
per Amplifier, Shutdown

Output Leakage Current, Shutdown VS = ±15V, V

Differential Gain (Note 6) VS = ±15V, RF = 560Ω, RG = 560Ω, RL = 30Ω 0.02 %
Differential Phase (Note 6) VS = ±15V, RF = 560Ω, RG = 560Ω, RL = 30Ω 0.17 DEG

SHDN A

= 0V, V

VS = ±5V, V
VS = ±15V, V

V

= ±5V, V

S

V

= ±5V, RL = 25Ω, TA = 25°C ±2.5 ±3.0 V

S

= 0V, unless otherwise noted.

SHDN B

= ±10V, RL = 50Ω ● 55 71 dB

OUT

= ±2V, RL = 25Ω ● 55 68 dB

OUT

= ±10V, RL = 50Ω ● 100 260 kΩ

OUT

= ±2V, RL = 25Ω ● 75 200 kΩ

OUT

● ±10.0 V

● ±2.0 V

= 0V, TA = 25°C2030mA

SHDN

SHDN A

SHDN

= 15V, V

= 15V, V

= 15V ● 200 µA

SHDN B

= 0V ● 10 µA

OUT

●35 mA

RF = RG = 620Ω, RL = 100Ω
VS = ±15V, Peaking ≤ 0.5dB 52 MHz

R

= RG = 649Ω, RL = 50Ω

F

VS = ±15V, Peaking ≤ 0.5dB 43 MHz
RF = RG = 698Ω, RL = 30Ω

VS = ±15V, Peaking ≤ 0.5dB 27 MHz
R

= RG = 825Ω, RL = 10Ω

F

● denotes specifications which apply for 0°C ≤ T

The

≤ 70°C.

A

Note 1: Applies to short circuits to ground only. A short circuit between
the output and either supply may permanently damage the part when
operated on supplies greater than ±10V.
Note 2: Commercial grade parts are designed to operate over the
temperature range of –40°C to 85°C but are neither tested nor guaranteed
beyond 0°C to 70°C. Industrial grade parts tested over –40°C to 85°C are
available on special request. Consult factory.

Note 3: Thermal resistance θ

varies from 40°C/W to 60°C/W depending

JA

upon the amount of PC board metal attached to the device. θJA is specified
for a 2500mm2 test board covered with 2oz copper on both sides.
Note 4: R

is connected between the Shutdown pin and ground.

SHDN

Note 5: Slew rate is measured at ±5V on a ±10V output signal while
operating on ±15V supplies with R

= 1.5k, RG = 1.5k and RL = 400Ω.

F

Note 6: NTSC composite video with an output level of 2V.

3

LT1207

WU

U

S ALL-SIG AL BA DWIDTH

I

= 20mA per Amplifier Typical, Peaking ≤ 0.1dB

S

A

VS = ±5V, R

–1 150 562 562 48 21.4

10 150 442 48.7 40 19.2

R

V

SHDN

30 649 649 34 17
10 732 732 22 12.5

1 150 619 – 54 22.3

30 715 – 36 17.5
10 806 – 22.4 11.5

2 150 576 576 48 20.7

30 649 649 35 18.1
10 750 750 22.4 11.7

30 511 56.2 31 16.5
10 649 71.5 20 10.2

L

= 0Ω

R

R

F

G

IS = 10mA per Amplifier Typical, Peaking ≤ 0.1dB

A

VS = ±5V, R

–1 150 576 576 35 17

10 150 301 33.2 31 15.6

R

V

SHDN

30 681 681 25 12.5
10 750 750 16.4 8.7

1 150 665 – 37 17.5

30 768 – 25 12.6
10 845 – 16.5 8.2

2 150 590 590 35 16.8

30 681 681 25 13.4
10 768 768 16.2 8.1

30 392 43.2 23 11.9
10 499 54.9 15 7.8

L

= 10.2k

R

R

F

G

–3dB BW –0.1dB BW

(MHz) (MHz)

–3dB BW –0.1dB BW

(MHz) (MHz)

A

VS = ±15V, R

–1 150 681 681 50 19.2

1 150 768 – 66 22.4

2 150 665 665 55 23

10 150 487 536 44 20.7

A

VS = ±15V, R

–1 150 634 634 41 19.1

1 150 768 – 44 18.8

2 150 649 649 40 18.5

10 150 301 33.2 33 15.6

R

V

SHDN

30 768 768 35 17
10 887 887 24 12.3

30 909 – 37 17.5
10 1k – 23 12

30 787 787 36 18.5
10 931 931 22.5 11.8

30 590 64.9 33 17.5
10 768 84.5 20.7 10.8

R

V

SHDN

30 768 768 26.5 14
10 866 866 17 9.4

30 909 – 28 14.4
10 1k – 16.8 8.3

30 787 787 27 14.1
10 931 931 16.5 8.1

30 402 44.2 25 13.3
10 590 64.9 15.3 7.4

L

L

R

F

= 0Ω

R

F

= 60.4k

R

G

R

G

–3dB BW –0.1dB BW

(MHz) (MHz)

–3dB BW –0.1dB BW

(MHz) (MHz)

IS = 5mA per Amplifier Typical, Peaking ≤ 0.1dB

A

VS = ±5V, R

–1 150 604 604 21 10.5

10 150 100 11.1 16.2 5.8

R

V

SHDN

30 715 715 14.6 7.4
10 681 681 10.5 6.0

1 150 768 – 20 9.6

2 150 634 634 20 9.6

30 866 – 14.1 6.7
10 825 – 9.8 5.1

30 750 750 14.1 7.2
10 732 732 9.6 5.1

30 100 11.1 13.4 7.0
10 100 11.1 9.5 4.7

L

= 22.1k

R

F

R

G

–3dB BW –0.1dB BW

(MHz) (MHz)

4

A

VS = ±15V, R

–1 150 619 619 25 12.5

10 150 100 11.1 15.9 4.5

R

V

SHDN

30 787 787 15.8 8.5
10 825 825 10.5 5.4

1 150 845 – 23 10.6

30 1k – 15.3 7.6
10 1k – 10 5.2

2 150 681 681 23 10.2

30 845 845 15 7.7
10 866 866 10 5.4

30 100 11.1 13.6 6
10 100 11.1 9.6 4.5

L

R

= 121k

F

R

G

–3dB BW –0.1dB BW

(MHz) (MHz)

WU

CAPACITIVE LOAD (pF)

1

100

FEEDBACK RESISTOR (Ω)

1k

10k

100 10000

LT1207 • TPC03

10 1000

BANDWIDTH

FEEDBACK RESISTOR
A

V

= 2

R

L

= ∞

V

S

= ±15V

C

COMP

= 0.01µF

1

10

100

–3dB BANDWIDTH (MHz)

TYPICAL PERFOR A CE CHARACTERISTICS

Bandwidth vs Supply Voltage

100

90
80
70
60
50
40
30

–3dB BANDWIDTH (MHz)

20
10

0

PEAKING ≤ 0.5dB
PEAKING ≤ 5dB

RF = 470Ω

RF = 560Ω

4

610

8

SUPPLY VOLTAGE (±V)

12

Bandwidth vs Supply Voltage

100

90
80
70

60

50
40
30

–3dB BANDWIDTH (MHz)

20
10

0

PEAKING ≤ 0.5dB
PEAKING ≤ 5dB

RF =390Ω

4

610

8

SUPPLY VOLTAGE (±V)

12

AV = 2

= 100Ω

R

L

RF = 680Ω

RF = 750Ω

RF = 1.5k

14

LT1207 • TPC01

AV = 10

= 100Ω

R

L

RF = 330Ω

RF = 470Ω

RF = 680Ω

RF = 1.5k

14

LT1207 • TPC04

RF = 1k

16

16

18

18

Bandwidth vs Supply Voltage

50

40

30

20

–3dB BANDWIDTH (MHz)

10

0

PEAKING ≤ 0.5dB
PEAKING ≤ 5dB

RF = 560Ω

RF = 750Ω

RF = 1k

RF = 2k

4

610

8

SUPPLY VOLTAGE (±V)

12

Bandwidth vs Supply Voltage

50

40

30

20

–3dB BANDWIDTH (MHz)

10

0

PEAKING ≤ 0.5dB
PEAKING ≤ 5dB

4

610

8

SUPPLY VOLTAGE (±V)

12

AV = 2

= 10Ω

R

L

16

14

LT1207 • TPC02

AV = 10

= 10Ω

R

L

RF = 560Ω

RF = 680Ω

RF = 1k
RF = 1.5k

16

14

LT1207 • TPC05

LT1207

Bandwidth and Feedback Resistance
vs Capacitive Load for 0.5dB Peak

18

Bandwidth and Feedback Resistance
vs Capacitive Load for 5dB Peak

10k



BANDWIDTH





1k



FEEDBACK RESISTOR (Ω)

FEEDBACK RESISTOR



0

0

100

18

1

10 100 1k 10k

CAPACITIVE LOAD (pF)

AV = +2

= ∞

R

L

= ±15V

V

S

C

COMP

= 0.01µF

LT1207 • TPC06

100

–3dB BANDWIDTH (MHz)

10

1

Differential Phase
vs Supply Voltage

0.50

0.40

0.30
RF = RG = 560Ω

= 2

A

V

N PACKAGE

0.20

DIFFERENTIAL PHASE (DEG)

0.10

0

7

5

11

9

SUPPLY VOLTAGE (±V)

RL = 15Ω

RL = 30Ω

RL = 50Ω

RL = 150Ω

13

LT1207 • TPC07

DIFFERENTIAL GAIN (%)

15

Differential Gain
vs Supply Voltage

0.10

0.08

0.06

0.04

0.02

0

RL = 15Ω

RL = 30Ω

RL = 150Ω

7

5

SUPPLY VOLTAGE (±V)

RL = 50Ω

9

RF = RG = 560Ω

= 2

A

V

N PACKAGE

11

13

LT1207 • TPC08

Spot Noise Voltage and Current
vs Frequency

100

–i

n

10

e

n

i

SPOT NOISE (nV/√Hz OR pA/√Hz)

15

1

10

100 100k

n

1k 10k

FREQUENCY (Hz)

LT1207 • TPC09

5

LT1207

WU

TYPICAL PERFOR A CE CHARACTERISTICS

Supply Current vs Supply Voltage

24

V

= 0V

SHDN

22

20

18

16

14

12

SUPPLY CURRENT PER AMPLIFIER (mA)

10

4

610

TJ = –40˚C

TJ = 25˚C

TJ = 85˚C

TJ = 125˚C

8

SUPPLY VOLTAGE (±V)

12

Supply Current
vs Shutdown Pin Current

20

VS = ±15V

18
16
14
12
10

8
6
4
2

SUPPLY CURRENT PER AMPLIFIER (mA)

0

100

0

SHUTDOWN PIN CURRENT (µA)

200

300

14

16

LT1207 • TPC10

400

LT1207 • TPC13

Supply Current vs
Ambient Temperature, VS = ±5V

25

–25

RSD = 0Ω

RSD = 10.2k

R

SD

0

= 22.1k

TEMPERATURE (°C)

20

15

10

5

SUPPLY CURRENT PER AMPLIFIER (mA)

0

18

–50

Input Common Mode Limit
vs Junction Temperature

+

V

– 0.5

–1.0

–1.5

–2.0

2.0

1.5

1.0

COMMON MODE RANGE (V)

0.5

–

500

V

–25 100

–50

0 125
TEMPERATURE (°C)

Supply Current vs
Ambient Temperature, VS = ±15V

AV = 1

=

∞

R

L

50

25

75

100

LT1207 • TPC11

125

25

RSD = 0Ω

20

15

0

–25

TEMPERATURE (°C)

RSD = 60.4k

R

= 121k

SD

25

10

5

SUPPLY CURRENT PER AMPLIFIER (mA)

0

–50

AV = 1

=

∞

R

L

50

75

100

LT1207 • TPC12

125

Output Short-Circuit Current
vs Junction Temperature

1.0

0.9

0.8

0.7



0.6

0.5

0.4

OUTPUT SHORT-CIRCUIT CURRENT (A)

0.3
–50

50

25

75

LT1207 • TPC14

–25 0

SOURCING

SINKING

50 100 125

25 75

TEMPERATURE (°C)

LT1207 • TPC15

Output Saturation Voltage
vs Junction Temperature

+

V

VS = ±15V

–1

–2

–3

–4

4

3

2

OUTPUT SATURATION VOLTAGE (V)

1

–

V

–25 100

–50

0 125

25

TEMPERATURE (°C)

6

50

RL = 2k

RL = 50Ω

RL = 50Ω

RL = 2k

75

LT1207 • TPC16

Power Supply Rejection Ratio
vs Frequency

70

60

NEGATIVE

50

POSITIVE

40

30

20

POWER SUPPLY REJECTION (dB)

10

0

10k 1M 10M 100M

100k

FREQUENCY (Hz)

RL = 50Ω

= ±15V

V

S

= RG = 1k

R

F

LT1207 • TPC17

Supply Current vs Large-Signal
Output Frequency (No Load)

60

AV = 2

= ∞

R

L

= ±15V

V

S

50

40

30

20

SUPPLY CURRENT PER AMPLIFIER (mA)

10

10k

= 20V

V

OUT

P-P

100k 1M 10M

FREQUENCY (Hz)

LT1207 • TPC18

WU

TYPICAL PERFOR A CE CHARACTERISTICS

LT1207

Output Impedance vs Frequency

100

VS = ±15V

= 0mA

I

O

R

= 121k

10

1

0.1

OUTPUT IMPEDANCE (Ω)

0.01
100k 10M 100M

SHDN

R

SHDN

1M

FREQUENCY (Hz)

60

50

40

30

3rd ORDER INTERCEPT (dBm)

20

LT1207 • TPC19

= 0Ω

Output Impedance in Shutdown
vs Frequency

100k

10k

1k

100

OUTPUT IMPEDANCE (Ω)

10

100k 10M 100M

1M

FREQUENCY (Hz)

AV = 1

= 1k

R

F

= ±15V

V

S

LT1207 • TPC20

Test Circuit for 3rd Order Intercept3rd Order Intercept vs Frequency

VS = ±15V

= 50Ω

R

L

= 590Ω

R

F

= 64.9Ω

R

G

2nd and 3rd Harmonic Distortion
vs Frequency

–30

–40

–50

–60

–70

DISTORTION (dBc)

–80

–90

1

+

1/2 LT1207

–

590Ω



65Ω



MEASURE INTERCEPT AT P

V

= ±15V

S

= 2V

V

O

P-P

RL = 10Ω

RL = 30Ω

O

LT1207 • TPC23

2nd

3rd

2nd

3rd

310

2456789

FREQUENCY (MHz)

P

O

50Ω


LT1207 • TPC21

10

0

10 15 20

5

FREQUENCY (MHz)

25 30

LT1207 • TPC22

7

LT1207

WW

SI PLIFIED SCHE ATIC

TO ALL
CURRENT
SOURCES

+

V

Q5

Q2

Q1Q18

Q6

D1

Q10

Q11

Q15

PPLICATI

A

Q17

SHUTDOWN

U

O

S

I FOR ATIO

1.25k

WU

–

V

+

V

Q3

Q4

1/2 LT1207 CURRENT FEEDBACK AMPLIFIER

U

The LT1207 is a dual current feedback amplifier with high
output current drive capability. The device is stable with
large capacitive loads and can easily supply the high
currents required by capacitive loads. The amplifier will
drive low impedance loads such as cables with excellent
linearity at high frequencies.

Feedback Resistor Selection

The optimum value for the feedback resistors is a function
of the operating conditions of the device, the load imped­ance and the desired flatness of response. The Typical AC
Performance tables give the values which result in the
highest 0.1dB and 0.5dB bandwidths for various resistive
loads and operating conditions. If this level of flatness is
not required, a higher bandwidth can be obtained by use
of a lower feedback resistor. The characteristic curves of
Bandwidth vs Supply Voltage indicate feedback resistors
for peaking up to 5dB. These curves use a solid line when
the response has less than 0.5dB of peaking and a dashed

Q9

–

V

C

C

R

C

+

V

Q12

Q8

D2

Q7

Q16

50Ω

COMP–IN+IN

Q13

Q14

LT1207 • SS

OUTPUT

–

V

line when the response has 0.5dB to 5dB of peaking. The
curves stop where the response has more than 5dB of
peaking.

For resistive loads, the COMP pin should be left open (see
section on capacitive loads).

Capacitive Loads

Each amplifier in the LT1207 includes an optional com­pensation network for driving capacitive loads. This net­work eliminates most of the output stage peaking associ­ated with capacitive loads, allowing the frequency re­sponse to be flattened. Figure 1 shows the effect of the
network on a 200pF load. Without the optional compensa­tion, there is a 5dB peak at 40MHz caused by the effect of
the capacitance on the output stage. Adding a 0.01µF
bypass capacitor between the output and the COMP pins
connects the compensation and completely eliminates the
peaking. A lower value feedback resistor can now be used,
resulting in a response which is flat to 0.35dB to 30MHz.

8

LT1207

PPLICATI

A

VOLTAGE GAIN (dB)

12

VS = ±15V

10

8
6
4

2

NO COMPENSATION

0
–2
–4
–6

–8

1

U

O

S

I FOR ATIO

RF = 1.2k

COMPENSATION

RF = 2k

R

COMPENSATION

10 100

FREQUENCY (MHz)

WU

= 2k

F

LT1207 • F01

U

Figure 1.

The network has the greatest effect for CL in the range of
0pF to 1000pF. The graph of Maximum Capacitive Load vs
Feedback Resistor can be used to select the appropriate
value of the feedback resistor. The values shown are for

0.5dB and 5dB peaking at a gain of 2 with no resistive load.
This is a worst-case condition, as the amplifier is more stable
at higher gains and with some resistive load in parallel with
the capacitance. Also shown is the –3dB bandwidth with the
suggested feedback resistor vs the load capacitance.

Although the optional compensation works well with
capacitive loads, it simply reduces the bandwidth when it
is connected with resistive loads. For instance, with a 30Ω
load, the bandwidth drops from 55MHz to 35MHz when
the compensation is connected. Hence, the compensation
was made optional. To disconnect the optional compensa­tion, leave the COMP pin open.

typically 100µA. Each Shutdown pin is referenced to the
positive supply through an internal bias circuit (see the
Simplified Schematic). An easy way to force shutdown is
to use open drain (collector) logic. The circuit shown in
Figure 2 uses a 74C904 buffer to interface between 5V
logic and the LT1207. The switching time between the
active and shutdown states is less than 1µ s.

A 24k pull-up
resistor speeds up the turn-off time and insures that the
amplifier is completely turned off. Because the pin is
referenced to the positive supply, the logic used should
have a breakdown voltage of greater than the positive
supply voltage. No other circuitry is necessary as the
internal circuit limits the Shutdown pin current to about
500µ A. Figure 3 shows the resulting waveforms.

15V

IN

5V

74C906

+

1/2 LT1207

SHDN

–

–15V

15V

24k

LT1207 • F02

V

OUT

R

F

R

G

V

ENABLE

Figure 2. Shutdown Interface

Shutdown/Current Set
If the shutdown feature is not used, the Shutdown pins

must be connected to ground or V–.

Each amplifier has a separate Shutdown pin which can be
used to either turn off the amplifier, which reduces the
amplifier supply current to less than 200µ A, or to control
the supply current in normal operation.

The supply current in each amplifier is controlled by the
current flowing out of the Shutdown pin. When the Shut­down pin is open or driven to the positive supply, the
amplifier is shut down. In the shutdown mode, the output
looks like a 40pF capacitor and the supply current is

OUT

V

ENABLE

AV = 1
R

= 825Ω

F

= 50Ω

R

L

= 24k

R

PU

= 1V

V

IN

P-P

LT1207 • F3

Figure 3. Shutdown Operation

For applications where the full bandwidth of the amplifier
is not required, the quiescent current may be reduced by
connecting a resistor from the Shutdown pin to ground.

9

LT1207

PPLICATI

A

U

O

S

I FOR ATIO

WU

U

The amplifier’s supply current will be approximately 40
times the current in the Shutdown pin. The voltage across
the resistor in this condition is V+ – 3VBE. For example, a
60k resistor will set the amplifier’s supply current to 10mA
with VS = ±15V.

The photos (Figures 4a and 4b) show the effect of reducing
the quiescent supply current on the large-signal response.
The quiescent current can be reduced to 5mA in the
inverting configuration without much change in response.
In noninverting mode, however, the slew rate is reduced
as the quiescent current is reduced.

and for higher gains in the noninverting mode, the signal
amplitude on the input pins is small and the overall slew
rate is that of the output stage. The input stage slew rate
is related to the quiescent current and will be reduced as
the supply current is reduced. The output slew rate is set
by the value of the feedback resistors and the internal
capacitance. Larger feedback resistors will reduce the
slew rate as will lower supply voltages, similar to the way
the bandwidth is reduced. The photos (Figures 5a, 5b and
5c) show the large-signal response of the LT1207 or
various gain configurations. The slew rate varies from
860V/µs for a gain of 1, to 1400V/µs for a gain of –1.

When the LT1207 is used to drive capacitive loads, the
available output current can limit the overall slew rate. In
the fastest configuration, the LT1207 is capable of a slew
rate of over 1V/ns. The current required to slew a capacitor

RF = 750Ω
R

= 50Ω

L

Figure 4a. Large-Signal Response vs IQ, AV = –1

RF = 750Ω
R

= 50Ω

L

Figure 4b. Large-Signal Response vs IQ, AV = 2

= 5mA, 10mA, 20mA

I

Q

= ±15V

V

S

= 5mA, 10mA, 20mA

I

Q

= ±15V

V

S

LT1207 • F04a

LT1207 • F04b

Slew Rate

Unlike a traditional op amp, the slew rate of a current
feedback amplifier is not independent of the amplifier gain
configuration. There are slew rate limitations in both the
input stage and the output stage. In the inverting mode,

RF = 825Ω
R

= 50Ω

L

Figure 5a. Large-Signal Response, AV = 1

RF = RG = 750Ω
R

= 50Ω

L

Figure 5b. Large-Signal Response, AV = –1

= ±15V

V

S

V

S

= ±15V

LT1207 • F05a

LT1207 • F05b

10

LT1207

PPLICATI

A

RF = 750Ω

= 50Ω

R

L

U

O

S

I FOR ATIO

Figure 5c. Large-Signal Response, AV = 2

WU

LT1207 • F05c

U

at this rate is 1mA per picofarad of capacitance, so
10,000pF would require 10A! The photo (Figure 6) shows
the large-signal behavior with CL = 10,000pF. The slew
rate is about 60V/µs, determined by the current limit of
600mA.

Capacitance on the Inverting Input

Current feedback amplifiers require 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.

Power Supplies

The LT1207 will operate from single or split supplies from
±5V (10V 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 500µV per volt of supply mis-
match. The inverting bias current can change as much as
5µ A per volt of supply mismatch, though typically the
change is less than 0.5µA per volt.

Thermal Considerations

VS = ±15V

= RG = 3k

R

F

Figure 6. Large-Signal Response, CL = 10,000pF

R

= ∞

L

LT1207 • F06

Differential Input Signal Swing

The differential input swing is limited to about ±6V by an
ESD protection device connected between the inputs. In
normal operation, the differential voltage between the
input pins is small, so this clamp has no effect; however,
in the shutdown mode the differential swing can be the
same as the input swing. The clamp voltage will then set
the maximum allowable input voltage. To allow for some
margin, it is recommended that the input signal be less
than ± 5V when the device is shut down.

Each amplifier in the LT1207 includes a separate thermal
shutdown circuit which protects against excessive inter­nal (junction) temperature. If the junction temperature
exceeds the protection threshold, the amplifier will begin
cycling between normal operation and an off state. The
cycling is not harmful to the part. The thermal cycling
occurs at a slow rate, typically 10ms to several seconds,
which depends on the power dissipation and the thermal
time constants of the package and heat sinking. Raising
the ambient temperature until the device begins thermal
shutdown gives a good indication of how much margin
there is in the thermal design.

Heat flows away from the amplifier through the package’s
copper lead frame. Heat sinking is accomplished by using
the heat spreading capabilities of the PC board and its
copper traces. Experiments have shown that the heat
spreading copper layer does not need to be electrically
connected to the tab of the device. The PCB material can
be very effective at transmitting heat between the pad area
attached to the tab of the device and a ground or power
plane layer either inside or on the opposite side of the
board. Although the actual thermal resistance of the PCB
material is high, the length/area ratio of the thermal

11

LT1207

–

+

15V

–15V

0.01µF

1k

330Ω

1k 200pF

–12V

12V

f = 2MHz

37.5mA

I

LT1206 • F07

1/2 LT1207

SHDN

PPLICATI

A

U

O

S

I FOR ATIO

WU

U

resistance between the layer is small. Copper board stiff­eners and plated through holes can also be used to spread
the heat generated by the device.

Table 1 lists thermal resistance for several different board
sizes and copper areas. All measurements were taken in
still air on 3/32" FR-4 board with 2oz copper. This data can
be used as a rough guideline in estimating thermal resis­tance. The thermal resistance for each application will be
affected by thermal interactions with other components as
well as board size and shape.

Table 1. Fused 16-Lead SO Package

COPPER AREA (2oz)

TOPSIDE BACKSIDE COPPER AREA (JUNCTION-TO-AMBIENT)

2500 sq. mm 2500 sq. mm 5000 sq. mm 40°C/W
1000 sq. mm 2500 sq. mm 3500 sq. mm 46°C/W
600 sq. mm 2500 sq. mm 3100 sq. mm 48°C/W
180 sq. mm 2500 sq. mm 2680 sq. mm 49°C/W
180 sq. mm 1000 sq. mm 1180 sq. mm 56°C/W
180 sq. mm 600 sq. mm 780 sq. mm 58°C/W
180 sq. mm 300 sq. mm 480 sq. mm 59°C/W
180 sq. mm 100 sq. mm 280 sq. mm 60°C/W
180 sq. mm 0 sq. mm 180 sq. mm 61°C/W

TOTAL THERMAL RESISTANCE

where:

TJ = Junction Temperature
TA = Ambient Temperature
PD = Device Dissipation

θJA = Thermal Resistance (Junction-to-Ambient)

As an example, calculate the junction temperature for the
circuit in Figure 8 assuming a 70°C ambient temperature.

The device dissipation can be found by measuring the
supply currents, calculating the total dissipation and then
subtracting the dissipation in the load and feedback
network.

Figure 8. Thermal Calculation Example

70

60

50

40

30

20

THERMAL RESISTANCE (°C/W)

10

0

0

1000



Figure 7. Thermal Resistance vs Total Copper Area
(Top + Bottom)

COPPER AREA (mm2)

2000

3000 4000

5000

LT1207 • F07

Calculating Junction Temperature

The junction temperature can be calculated from the
equation:

TJ = (PD)(θJA) + T

12

A

The dissipation for each amplifier is:

PD = (37.5mA)(30V) – (12V)2/(1k||1k) = 0.837W

The total dissipation is PD = 1.674W. When a 2500 sq mm
PC board with 2oz copper on top and bottom is used, the
thermal resistance is 40°C/W. The junction temperature TJ is:

TJ = (1.674W)(40°C/W) + 70°C = 137°C

The maximum junction temperature for the LT1207 is
150°C, so the heat sinking capability of the board is
adequate for the application.

If the copper area on the PC board is reduced to 280mm

2

the thermal resistance increases to 60°C/W and the junc­tion temperature becomes:

TJ = (1.674W)(60°C/W) + 70°C = 170°C

Which is above the maximum junction temperature indi­cating that the heat sinking capability of the board is
inadequate and should be increased.

U

TYPICAL APPLICATIO S

LT1207

Gain of Eleven High Current Amplifier

V

+

IN

LT1097

–

OUTPUT OFFSET: < 500µV
SLEW RATE: 2V/µs
BANDWIDTH: 4MHz
STABLE WITH C

+

LT1115

–

+

SHDN

–

500pF

1k

< 10nF

L

Gain of Ten Buffered Line Driver

15V

1µF

+

15V

1µF

+

+

1µF

+

1/2 LT1207

SHDN

–

1/2 LT1207

COMP

0.01µF

3k330Ω

10k

0.01µF

LT1207 • TA02

OUT

OUTPUT

R

L

100Ω

–15V

68pF

–15V

909Ω

= 32Ω

R

L

= 5V

RMS



V

O

THD + NOISE = 0.0009% AT 1kHz
 = 0.004% AT 20kHz
SMALL-SIGNAL 0.1dB BANDWIDTH = 600kHz

1µF

560Ω560Ω

+

LT1207 • TA03

13

LT1207

–

+

+

–

1k

1k

1k

0.01µF

0.01µF

500Ω

+

–

V

IN

V

OUT

LT1207 • TA07

1/2 LT1207

1/2 LT1207

U

TYPICAL APPLICATIO S

CMOS Logic to Shutdown Interface

15V

V

IN

75Ω

+

1/2 LT1207

SHDN

–

10k

–15V

2N3904

5V

24k

LT1207 • TA04

Buffer AV = 1

+

–

1/2 LT1207

COMP

SHDN

RF**

0.01µF*

LT1207 • TA06

V

OPTIONAL, USE WITH CAPACITIVE LOADS

*

OUT

VALUE OF R

**

VOLTAGE AND LOADING. SELECT 
FROM TYPICAL AC PERFORMANCE 
TABLE OR DETERMINE EMPIRICALLY

DEPENDS ON SUPPLY

F

V

IN

Distribution Amplifier

+

1/2 LT1207

SHDN

–

R

F

R

G

Differential Output Driver

75Ω

75Ω

75Ω

75Ω CABLE

75Ω

LT1207 • TA05

Differential Input—Differential Output Power Amplifier (AV = 4)

1k

+

1/2 LT1207

–

1k

1k

–

1/2 LT1207

+

V

OUT

LT1207 • TA08

+

–

+

V

IN

–

14

U

TYPICAL APPLICATIO S

Paralleling Both CFAs for Guaranteed 500mA Output Drive Current

LT1207

PACKAGE DESCRIPTIO

V

IN

+

1/2 LT1207

3Ω

V

OUT

–

1k

1k

+

1/2 LT1207

3Ω

–

1k

1k

LT1207 • TA09

U

Dimensions in inches (millimeters) unless otherwise noted.

S Package

16-Lead Plastic Small Outline (Narrow 0.150)

(LTC DWG # 05-08-1610)

0.010 – 0.020

(0.254 – 0.508)

0.008 – 0.010

(0.203 – 0.254)

*

DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH 


SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE

**

DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD 
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE



× 45°

0.016 – 0.050

0.406 – 1.270

0° – 8° TYP

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 represen­tation that the interconnection of circuits as described herein will not infringe on existing patent rights.

0.228 – 0.244

(5.791 – 6.197)

0.053 – 0.069

(1.346 – 1.752)

0.014 – 0.019

(0.355 – 0.483)

0.386 – 0.394*

(9.804 – 10.008)

13

4

12

5

0.050

(1.270)

TYP

11 10

6

9

0.150 – 0.157**
(3.810 – 3.988)

7

8

0.004 – 0.010

(0.101 – 0.254)

S16 0695

16

1

14

15

3

2

15

LT1207

TYPICAL APPLICATION

CCD Clock Driver. Two 3rd Order Gaussian Filters Produce Clean CCD Clock Signals

U

CLOCK

INPUT

DRIVER

OUTPUT

45pF

20V

CLOCK

INPUT

5
0

15

0

CLKDQ

74HC74

Q

1k

1k

1k 1k

100pF

1k 1k

100pF

91pF

91pF

+

1/2 LT1207

–

510Ω

45pF

+

1/2 LT1207

–

510Ω

–10V

0.01µF

1k

0.01µF

1k

CCD ARRAY LOAD

10Ω

3300pF

10Ω

3300pF

LT1207 • TA10

RELATED PARTS

PART NUMBER DESCRIPTION COMMENTS

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C

L

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Gain, 0.3° Differential Phase with A

C-Load is a trademark of Linear Technology Corporation

Linear Technology Corporation

16

1630 McCarthy Blvd., Milpitas, CA 95035-7417

[phone]

●

FAX

: [phone]

●

TELEX

: 499-3977

= 2 and RL = 30Ω, Stable with

V

, 0.2% Differential

= 2 and RL = 150Ω

V

 LINEAR TECHNOL OGY CO RP O RATION 1 996

OS

LT/GP 0196 10K • PRINTED IN USA