LT1207CS [Linear]
Dual 250mA/60MHz Current Feedback Amplifier; 双250毫安/ 60MHz的电流反馈放大器
| 型号： | LT1207CS |
| 厂家： | 
Linear |
| 描述： | Dual 250mA/60MHz Current Feedback Amplifier |
| 文件： | 总16页 (文件大小：368K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LT1207
Dual 250mA/60MHz
Current Feedback Amplifier
U
DESCRIPTIO
EATURE
S
F
The LT®1207 is a dual version of the LT1206 high speed
current feedback amplifier. Like the LT1206, each CFA in
thedualhasexcellentvideocharacteristics:60MHzband-
width, 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 stabi-
lizes the amplifier for heavy capacitive loads. Both ampli-
fiershavethermalandcurrentlimitcircuitswhichprotect
againstfaultconditions.ThesecapabilitiesmaketheLT1207
well suited for driving difficult loads such as cables in video
or digital communication systems.
■
■
■
■
■
■
■
■
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
U
APPLICATIO S
■
ADSL/HDSL Drivers
■
Video Amplifiers
■
Cable Drivers
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.
■
RGB Amplifiers
■
Test Equipment Amplifiers
■
Buffers
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.
U
TYPICAL APPLICATION
HDSL Driver
5V
+
0.1µF*
2.2µF**
+
V
IN
SHDN A
1/2 LT1207
62Ω
–
L1
720Ω
720Ω
720Ω
15k
15k
240Ω
–
*CERAMIC
**TANTALUM
62Ω
SHDN B
1/2 LT1207
L1 = TRANSPOWER SMPT–308
OR SIMILAR DEVICE
+
+
2.2µF**
0.1µF*
–5V
1207 • TA01
1
LT1207
W W W
U
ABSOLUTE AXI U RATI GS
/O
PACKAGE RDER I FOR ATIO
Supply Voltage ..................................................... ±18V
Input Current per Amplifier ............................... ±15mA
Output Short-Circuit Duration (Note 1)....... Continuous
Specified Temperature Range (Note 2)...... 0°C to 70°C
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
TOP VIEW
ORDER PART
+
+
NUMBER
V
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
V
–IN A
+IN A
OUT A
–
LT1207CS
V
A
SHDN A
–IN B
COMP A
OUT B
–
+IN B
V
B
SHDN B
COMP B
+
+
V
V
S PACKAGE
16-LEAD PLASTIC SO
θJA = 40°C/W (NOTE 3)
Consult factory for Industrial and Military grade parts.
ELECTRICAL CHARACTERISTICS
VCM = 0, ±5V ≤ VS ≤ ±15V, pulse tested, VSHDN A = 0V, VSHDN B = 0V, unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
T = 25°C
MIN
TYP
MAX
UNITS
V
OS
Input Offset Voltage
±3
±10
±15
mV
mV
A
●
●
Input Offset Voltage Drift
Noninverting Input Current
10
µV/°C
+
I
I
T = 25°C
A
±2
±5
±20
µA
µA
IN
●
●
–
Inverting Input Current
T = 25°C
A
±10
±60
±100
µA
µA
IN
e
Input Noise Voltage Density
Input Noise Current Density
Input Noise Current Density
Input Resistance
f = 10kHz, R = 1k, R = 10Ω, R = 0Ω
3.6
2
nV/√Hz
pA/√Hz
pA/√Hz
n
F
G
S
+i
–i
f = 10kHz, R = 1k, R = 10Ω, R = 10k
F G S
n
f = 10kHz, R = 1k, R = 10Ω, R = 10k
30
n
F
G
S
R
V
IN
V
IN
= ±12V, V = ±15V
●
●
1.5
0.5
10
5
MΩ
MΩ
IN
S
= ±2V, V = ±5V
S
C
IN
Input Capacitance
V = ±15V
S
2
pF
Input Voltage Range
V = ±15V
S
●
●
±12
±2
±13.5
±3.5
V
V
S
V = ±5V
CMRR
PSRR
Common Mode Rejection Ratio
V = ±15V, V = ±12V
●
●
55
50
62
60
dB
dB
S
CM
V = ±5V, V = ±2V
S
CM
Inverting Input Current
Common Mode Rejection
V = ±15V, V = ±12V
●
●
0.1
0.1
10
10
µA/V
µA/V
S
CM
V = ±5V, V = ±2V
S CM
Power Supply Rejection Ratio
V = ±5V to ±15V
S
●
60
77
dB
2
LT1207
ELECTRICAL CHARACTERISTICS
VCM = 0, ±5V ≤ VS ≤ ±15V, pulse tested, VSHDN A = 0V, VSHDN B = 0V, unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
V = ±5V to ±15V
MIN
TYP
MAX
UNITS
Noninverting Input Current
Power Supply Rejection
●
●
30
500
nA/V
S
Inverting Input Current
Power Supply Rejection
V = ±5V to ±15V
S
0.7
5
µA/V
A
Large-Signal Voltage Gain
V = ±15V, V
= ±10V, R = 50Ω
●
●
55
55
71
68
dB
dB
V
S
OUT
L
V = ±5V, V
= ±2V, R = 25Ω
L
S
OUT
–
R
Transresistance, ∆V /∆I
V = ±15V, V
= ±10V, R = 50Ω
●
●
100
75
260
200
kΩ
kΩ
OL
OUT IN
S
OUT
L
V = ±5V, V
= ±2V, R = 25Ω
S
OUT
L
V
Maximum Output Voltage Swing
V = ±15V, R = 50Ω, T = 25°C
±11.5
±10.0
±2.5
±12.5
V
V
V
V
OUT
S
L
A
●
V = ±5V, R = 25Ω, T = 25°C
±3.0
S
L
A
●
●
±2.0
I
I
Maximum Output Current
R = 1Ω
L
250
500
20
1200
mA
OUT
S
Supply Current per Amplifier
V = ±15V, V
= 0V, T = 25°C
30
35
mA
mA
S
SHDN
A
●
Supply Current per Amplifier,
SHDN
V = ±15V, T = 25°C
12
17
200
10
mA
S
A
R
= 51k (Note 4)
Positive Supply Current
per Amplifier, Shutdown
V = ±15V, V
= 15V, V = 15V
SHDN B
●
●
µA
S
SHDN A
Output Leakage Current, Shutdown
Slew Rate (Note 5)
V = ±15V, V
= 15V, V = 0V
OUT
µA
V/µs
%
S
SHDN
SR
A = 2, T = 25°C
400
900
0.02
0.17
60
V
A
Differential Gain (Note 6)
Differential Phase (Note 6)
Small-Signal Bandwidth
V = ±15V, R = 560Ω, R = 560Ω, R = 30Ω
S F G L
V = ±15V, R = 560Ω, R = 560Ω, R = 30Ω
DEG
MHz
S
F
G
L
BW
V = ±15V, Peaking ≤ 0.5dB
S
R = R = 620Ω, R = 100Ω
F
G
L
V = ±15V, Peaking ≤ 0.5dB
52
43
27
MHz
MHz
MHz
S
R = R = 649Ω, R = 50Ω
F
G
L
V = ±15V, Peaking ≤ 0.5dB
S
R = R = 698Ω, R = 30Ω
F
G
L
V = ±15V, Peaking ≤ 0.5dB
S
R = R = 825Ω, R = 10Ω
F
G
L
The
●
denotes specifications which apply for 0°C ≤ T ≤ 70°C.
Note 3: Thermal resistance θ varies from 40°C/W to 60°C/W depending
A
JA
upon the amount of PC board metal attached to the device. θ is specified
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.
JA
2
for a 2500mm test board covered with 2oz copper on both sides.
Note 4: R
is connected between the Shutdown pin and ground.
SHDN
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 5: Slew rate is measured at ±5V on a ±10V output signal while
operating on ±15V supplies with R = 1.5k, R = 1.5k and R = 400Ω.
F
G
L
Note 6: NTSC composite video with an output level of 2V.
3
LT1207
W
U
U
-
S ALL SIG AL BA DWIDTH
IS = 20mA per Amplifier Typical, Peaking ≤ 0.1dB
–3dB BW
(MHz)
–0.1dB BW
(MHz)
–3dB BW
(MHz)
–0.1dB BW
(MHz)
A
R
L
R
R
G
A
R
L
R
R
V
F
G
V
F
V = ±15V, R
S
= 0Ω
V = ±5V, R
S
= 0Ω
SHDN
SHDN
–1
1
150
681
768
887
768
909
1k
681
768
887
–
–
–
50
35
24
66
37
23
19.2
17
–1
1
150
30
562
649
732
619
715
806
562
649
732
–
–
–
48
34
22
54
36
22.4
21.4
17
30
10
12.3
10
12.5
150
30
10
22.3
17.5
11.5
150
30
10
22.4
17.5
12
2
150
30
10
576
649
750
576
649
750
48
35
22.4
20.7
18.1
11.7
2
150
30
10
665
787
931
665
787
931
55
36
22.5
23
18.5
11.8
10
150
30
10
442
511
649
48.7
56.2
71.5
40
31
20
19.2
16.5
10.2
10
150
30
10
487
590
768
536
64.9
84.5
44
33
20.7
20.7
17.5
10.8
IS = 10mA per Amplifier Typical, Peaking ≤ 0.1dB
–3dB BW
(MHz)
–0.1dB BW
(MHz)
–3dB BW
(MHz)
–0.1dB BW
(MHz)
A
R
L
R
R
G
A
R
L
R
R
V
F
V
F
G
V = ±5V, R
= 10.2k
V = ±15V, R
S
= 60.4k
S
SHDN
SHDN
–1
1
150
30
576
681
750
665
768
845
576
681
750
–
–
–
35
25
17
12.5
8.7
17.5
12.6
8.2
–1
1
150
634
768
866
768
909
1k
634
768
866
–
–
–
41
26.5
17
44
28
16.8
19.1
14
30
10
10
16.4
9.4
150
30
10
37
25
16.5
150
30
10
18.8
14.4
8.3
2
150
30
10
590
681
768
590
681
768
35
25
16.2
16.8
13.4
8.1
2
150
30
10
649
787
931
649
787
931
40
27
16.5
18.5
14.1
8.1
10
150
30
10
301
392
499
33.2
43.2
54.9
31
23
15
15.6
11.9
7.8
10
150
30
10
301
402
590
33.2
44.2
64.9
33
25
15.3
15.6
13.3
7.4
IS = 5mA per Amplifier Typical, Peaking ≤ 0.1dB
–3dB BW
(MHz)
–0.1dB BW
(MHz)
–3dB BW
(MHz)
–0.1dB BW
(MHz)
A
R
L
R
R
G
A
R
L
R
R
G
V
F
V
F
V = ±5V, R
= 22.1k
V = ±15V, R
S
= 121k
S
SHDN
SHDN
–1
1
150
30
604
715
681
604
715
681
21
10.5
7.4
–1
1
150
619
787
825
619
787
825
25
12.5
8.5
14.6
10.5
30
10
15.8
10.5
10
6.0
5.4
150
30
10
768
866
825
–
–
–
20
14.1
9.8
9.6
6.7
5.1
150
30
10
845
1k
1k
–
–
–
23
15.3
10
10.6
7.6
5.2
2
150
30
10
634
750
732
634
750
732
20
14.1
9.6
9.6
7.2
5.1
2
150
30
10
681
845
866
681
845
866
23
15
10
10.2
7.7
5.4
10
150
30
10
100
100
100
11.1
11.1
11.1
16.2
13.4
9.5
5.8
7.0
4.7
10
150
30
10
100
100
100
11.1
11.1
11.1
15.9
13.6
9.6
4.5
6
4.5
4
LT1207
W U
TYPICAL PERFOR A CE CHARACTERISTICS
Bandwidth and Feedback Resistance
Bandwidth vs Supply Voltage
Bandwidth vs Supply Voltage
vs Capacitive Load for 0.5dB Peak
10k
100
10
1
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
PEAKING ≤ 0.5dB
PEAKING ≤ 5dB
A
= 2
= 10Ω
A
= 2
= 100Ω
BANDWIDTH
PEAKING ≤ 0.5dB
PEAKING ≤ 5dB
V
L
V
L
R
R
R = 560Ω
F
R = 470Ω
F
R = 560Ω
F
R = 750Ω
F
R = 680Ω
F
1k
R = 1k
F
R = 750Ω
F
FEEDBACK RESISTOR
R = 2k
F
A
= 2
V
L
S
R = 1k
F
R
=
∞
V
C
= ±15V
COMP
R = 1.5k
F
= 0.01µF
100
1
10
100
1000
10000
4
12
14
16
4
12
14
16
6
8
10
18
6
8
10
18
CAPACITIVE LOAD (pF)
SUPPLY VOLTAGE (±V)
SUPPLY VOLTAGE (±V)
LT1207 • TPC03
LT1207 • TPC02
LT1207 • TPC01
Bandwidth and Feedback Resistance
vs Capacitive Load for 5dB Peak
Bandwidth vs Supply Voltage
Bandwidth vs Supply Voltage
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
10k
100
A
= 10
= 10Ω
PEAKING ≤ 0.5dB
PEAKING ≤ 5dB
A
= 10
= 100Ω
PEAKING ≤ 0.5dB
PEAKING ≤ 5dB
V
L
V
L
BANDWIDTH
R
R
R
=390Ω
R
F
= 330Ω
R = 560Ω
F
F
1k
10
R = 680Ω
F
R
R
= 470Ω
= 680Ω
F
R = 1k
F
A
= +2
F
V
L
FEEDBACK RESISTOR
R = 1.5k
F
R
= ∞
V
C
= ±15V
S
R
F
= 1.5k
= 0.01µF
COMP
100
1
10k
4
12
14
16
16
6
8
10
18
4
12
14
6
8
10
18
1
10
100
1k
SUPPLY VOLTAGE (±V)
SUPPLY VOLTAGE (±V)
CAPACITIVE LOAD (pF)
LT1207 • TPC05
LT1207 • TPC04
LT1207 • TPC06
Spot Noise Voltage and Current
vs Frequency
Differential Phase
vs Supply Voltage
Differential Gain
vs Supply Voltage
0.50
0.40
0.30
0.10
0.08
0.06
100
10
1
R = R = 560Ω
F
G
A
= 2
V
R
R
= 15Ω
= 30Ω
L
R
= 15Ω
= 30Ω
N PACKAGE
L
L
–i
n
R
A
= R = 560Ω
F
V
G
R
= 2
N PACKAGE
0.20
0.10
0
0.04
0.02
0
L
R
= 50Ω
L
e
n
R
R
= 50Ω
L
i
n
= 150Ω
L
R
7
= 150Ω
L
5
7
9
11
13
15
5
9
11
13
15
10
100
1k
FREQUENCY (Hz)
10k
100k
SUPPLY VOLTAGE (±V)
SUPPLY VOLTAGE (±V)
LT1207 • TPC09
LT1207 • TPC07
LT1207 • TPC08
5
LT1207
W U
TYPICAL PERFOR A CE CHARACTERISTICS
Supply Current vs
Ambient Temperature, VS = ±5V
Supply Current vs
Ambient Temperature, VS = ±15V
Supply Current vs Supply Voltage
24
22
20
25
20
15
10
5
25
20
15
10
5
V
= 0V
A
= 1
A = 1
V
SHDN
V
L
T = –40˚C
R
= 0Ω
J
R
=
∞
R = ∞
L
SD
R
= 0Ω
SD
T = 25˚C
J
18
16
14
R
R
= 10.2k
= 22.1k
R
R
= 60.4k
= 121k
SD
SD
T = 85˚C
J
SD
SD
T = 125˚C
J
12
10
0
0
50
75 100 125
4
12
14
16
50
125
–50
–25
0
25
6
8
10
18
–50
0
25
75 100
–25
SUPPLY VOLTAGE (±V)
TEMPERATURE (°C)
TEMPERATURE (°C)
LT1207 • TPC10
LT1207 • TPC12
LT1207 • TPC11
Supply Current
vs Shutdown Pin Current
Input Common Mode Limit
vs Junction Temperature
Output Short-Circuit Current
vs Junction Temperature
+
1.0
0.9
20
18
16
14
12
10
8
V
V
= ±15V
S
– 0.5
–1.0
–1.5
–2.0
2.0
0.8
0.7
0.6
0.5
0.4
SOURCING
SINKING
1.5
6
1.0
4
0.5
2
–
0.3
0
V
50
TEMPERATURE (°C)
100 125
0
100
200
300
400
500
–50 –25
0
25
75
–50 –25
0
100 125
25
50
75
SHUTDOWN PIN CURRENT (µA)
TEMPERATURE (°C)
LT1207 • TPC13
LT1207 • TPC15
LT1207 • TPC14
Supply Current vs Large-Signal
Output Frequency (No Load)
Output Saturation Voltage
vs Junction Temperature
Power Supply Rejection Ratio
vs Frequency
+
70
60
50
40
30
20
10
0
V
60
50
40
30
20
10
A
= 2
V
S
= ±15V
R
V
= 50Ω
V
L
S
R
= 2k
L
S
F
L
–1
–2
–3
–4
4
R
V
=
∞
= ±15V
NEGATIVE
POSITIVE
= ±15V
R
= R = 1k
G
V
= 20V
OUT
P-P
R
= 50Ω
L
R
R
= 50Ω
L
L
3
2
= 2k
1
–
V
10k
100k
1M
10M
100M
10k
100k
1M
10M
–50 –25
0
100 125
25
50
75
FREQUENCY (Hz)
TEMPERATURE (°C)
FREQUENCY (Hz)
LT1207 • TPC17
LT1207 • TPC18
LT1207 • TPC16
6
LT1207
W U
TYPICAL PERFOR A CE CHARACTERISTICS
Output Impedance in Shutdown
vs Frequency
2nd and 3rd Harmonic Distortion
vs Frequency
Output Impedance vs Frequency
–30
–40
–50
–60
–70
–80
–90
100
10
100k
10k
V
V
= ±15V
V
I
= ±15V
= 0mA
A
= 1
S
O
S
O
V
F
S
= 2V
R
= 1k
P-P
V
= ±15V
R
= 121k
2nd
SHDN
R
= 10Ω
L
3rd
2nd
R
= 0Ω
SHDN
1
1k
R
= 30Ω
L
3rd
0.1
100
0.01
100k
10
100k
1
2
3
4
5
6 7 8 9 10
1M
10M
100M
1M
10M
100M
FREQUENCY (MHz)
FREQUENCY (Hz)
FREQUENCY (Hz)
LT1207 • TPC21
LT1207 • TPC19
LT1207 • TPC20
3rd Order Intercept vs Frequency
Test Circuit for 3rd Order Intercept
60
50
40
30
V
= ±15V
= 50Ω
S
L
F
+
R
R
R
= 590Ω
= 64.9Ω
P
1/2 LT1207
O
G
–
590Ω
50Ω
65Ω
MEASURE INTERCEPT AT P
O
LT1207 • TPC23
20
10
0
10
15
20
25
30
5
FREQUENCY (MHz)
LT1207 • TPC22
7
LT1207
W
W
SI PLIFIED SCHE ATIC
+
V
TO ALL
CURRENT
SOURCES
Q5
Q10
Q2
D1
Q11
Q6
Q15
Q18
Q1
Q17
Q9
–
–
V
1.25k
50Ω
COMP
V
C
C
+IN
–IN
R
C
OUTPUT
+
V
SHUTDOWN
+
V
Q12
Q3
Q8
Q16
Q14
D2
Q4
Q13
Q7
–
V
LT1207 • SS
1/2 LT1207 CURRENT FEEDBACK AMPLIFIER
O U
W
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PPLICATI
A
S I FOR ATIO
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.
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
Feedback Resistor Selection
Each amplifier in the LT1207 includes an optional com-
pensation network for driving capacitive loads. This net-
work eliminates most of the output stage peaking associ-
ated with capacitive loads, allowing the frequency re-
sponse to be flattened. Figure 1 shows the effect of the
network on a 200pF load. Without the optional compensa-
tion, 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
connectsthecompensationandcompletelyeliminatesthe
peaking. A lower value feedback resistor can now be used,
resulting in a response which is flat to 0.35dB to 30MHz.
The optimum value for the feedback resistors is a function
of the operating conditions of the device, the load imped-
ance 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
8
LT1207
O U
W
U
PPLICATI
S I FOR ATIO
A
12
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 1µs. 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
500µA. Figure 3 shows the resulting waveforms.
V
= ±15V
S
10
8
R = 1.2k
COMPENSATION
F
6
4
2
R = 2k
F
NO COMPENSATION
0
R = 2k
F
–2
–4
–6
–8
COMPENSATION
1
10
100
FREQUENCY (MHz)
LT1207 • F01
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
0.5dBand5dBpeakingatagainof2withnoresistiveload.
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.
15V
V
+
IN
V
1/2 LT1207
SHDN
OUT
–
–15V
R
R
F
15V
24k
G
5V
ENABLE
LT1207 • F02
74C906
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
thecompensationisconnected. Hence, thecompensation
wasmadeoptional.Todisconnecttheoptionalcompensa-
tion, leave the COMP pin open.
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 200µA, or to control
the supply current in normal operation.
LT1207 • F3
AV = 1
RF = 825Ω
RL = 50Ω
RPU = 24k
VIN = 1VP-P
The supply current in each amplifier is controlled by the
current flowing out of the Shutdown pin. When the Shut-
down 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
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
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
60kresistorwillsettheamplifier’ssupplycurrentto10mA
with VS = ±15V.
O U
W
U
A
S I FOR ATIO
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.
Thephotos(Figures4aand4b)showtheeffectofreducing
thequiescentsupplycurrentonthelarge-signalresponse.
The quiescent current can be reduced to 5mA in the
invertingconfigurationwithoutmuchchangeinresponse.
In noninverting mode, however, the slew rate is reduced
as the quiescent current is reduced.
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
rateofover1V/ns. Thecurrentrequiredtoslewacapacitor
LT1207 • F04a
RF = 750Ω
L = 50Ω
IQ = 5mA, 10mA, 20mA
VS = ±15V
R
Figure 4a. Large-Signal Response vs IQ, AV = –1
LT1207 • F05a
RF = 825Ω
L = 50Ω
VS = ±15V
R
Figure 5a. Large-Signal Response, AV = 1
LT1207 • F04b
RF = 750Ω
L = 50Ω
IQ = 5mA, 10mA, 20mA
VS = ±15V
R
Figure 4b. Large-Signal Response vs IQ, AV = 2
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,
LT1207 • F05b
RF = RG = 750Ω
L = 50Ω
VS = ±15V
R
Figure 5b. Large-Signal Response, AV = –1
10
LT1207
O U
W
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PPLICATI
A
S
I FOR ATIO
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 invert-
ing 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
LT1207 • F05c
RF = 750Ω
RL = 50Ω
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
5µA per volt of supply mismatch, though typically the
change is less than 0.5µA per volt.
Figure 5c. Large-Signal Response, AV = 2
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.
Thermal Considerations
Each amplifier in the LT1207 includes a separate thermal
shutdown circuit which protects against excessive inter-
nal (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.
LT1207 • F06
VS = ±15V
RL = ∞
RF = RG = 3k
Figure 6. Large-Signal Response, CL = 10,000pF
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
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.
11
LT1207
PPLICATI
resistance between the layer is small. Copper board stiff-
eners and plated through holes can also be used to spread
the heat generated by the device.
O U
W
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A
S I FOR ATIO
where:
TJ = Junction Temperature
TA = Ambient Temperature
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 resis-
tance. The thermal resistance for each application will be
affectedbythermalinteractionswithothercomponentsas
well as board size and shape.
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
supplycurrents,calculatingthetotaldissipationandthen
subtracting the dissipation in the load and feedback
network.
Table 1. Fused 16-Lead SO Package
COPPER AREA (2oz)
TOTAL
THERMAL RESISTANCE
TOPSIDE
BACKSIDE COPPER AREA (JUNCTION-TO-AMBIENT)
15V
2500 sq. mm 2500 sq. mm 5000 sq. mm
1000 sq. mm 2500 sq. mm 3500 sq. mm
40°C/W
46°C/W
48°C/W
49°C/W
56°C/W
58°C/W
59°C/W
60°C/W
61°C/W
37.5mA
I
+
600 sq. mm
180 sq. mm
180 sq. mm
180 sq. mm
180 sq. mm
180 sq. mm
180 sq. mm
2500 sq. mm 3100 sq. mm
2500 sq. mm 2680 sq. mm
1000 sq. mm 1180 sq. mm
12V
1/2 LT1207
SHDN
–
330Ω
–12V
f = 2MHz
0.01µF
1k
200pF
600 sq. mm
300 sq. mm
100 sq. mm
0 sq. mm
780 sq. mm
480 sq. mm
280 sq. mm
180 sq. mm
–15V
1k
LT1206 • F07
Figure 8. Thermal Calculation Example
The dissipation for each amplifier is:
70
60
50
40
30
20
10
0
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
thermalresistanceis40°C/W.ThejunctiontemperatureTJ 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 280mm2
the thermal resistance increases to 60°C/W and the junc-
tion temperature becomes:
0
3000
4000
5000
1000
2000
2
COPPER AREA (mm )
LT1207 • F07
Figure 7. Thermal Resistance vs Total Copper Area
(Top + Bottom)
TJ = (1.674W)(60°C/W) + 70°C = 170°C
Calculating Junction Temperature
Which is above the maximum junction temperature indi-
cating that the heat sinking capability of the board is
inadequate and should be increased.
The junction temperature can be calculated from the
equation:
TJ = (PD)(θJA) + TA
12
LT1207
U
TYPICAL APPLICATIO S
Gain of Eleven High Current Amplifier
V
IN
+
1/2 LT1207
LT1097
+
–
OUT
COMP
SHDN
–
0.01µF
500pF
330Ω
3k
10k
LT1207 • TA02
OUTPUT OFFSET: < 500µV
SLEW RATE: 2V/µs
1k
BANDWIDTH: 4MHz
STABLE WITH C < 10nF
L
Gain of Ten Buffered Line Driver
15V
1µF
15V
1µF
+
+
+
–
LT1115
+
OUTPUT
1/2 LT1207
SHDN
–
1µF
+
0.01µF
R
L
–15V
1µF
68pF
+
–15V
560Ω
909Ω
560Ω
LT1207 • TA03
100Ω
R
O
= 32Ω
L
V
= 5V
RMS
THD + NOISE = 0.0009% AT 1kHz
= 0.004% AT 20kHz
SMALL-SIGNAL 0.1dB BANDWIDTH = 600kHz
13
LT1207
U
TYPICAL APPLICATIO S
CMOS Logic to Shutdown Interface
Distribution Amplifier
15V
V
+
IN
75Ω CABLE
75Ω
1/2 LT1207
75Ω
SHDN
+
–
75Ω
R
R
F
1/2 LT1207
SHDN
–
24k
75Ω
75Ω
LT1207 • TA05
LT1207 • TA04
5V
–15V
G
10k
2N3904
Buffer AV = 1
Differential Output Driver
1/2 LT1207
V
IN
+
V
+
–
IN
+
1/2 LT1207
COMP
SHDN
V
*OPTIONAL, USE WITH CAPACITIVE LOADS
**VALUE OF R DEPENDS ON SUPPLY
F
VOLTAGE AND LOADING. SELECT
FROM TYPICAL AC PERFORMANCE
TABLE OR DETERMINE EMPIRICALLY
OUT
–
0.01µF
0.01µF*
1k
R **
F
LT1207 • TA06
500Ω
1k
V
OUT
1k
–
Differential Input—Differential Output Power Amplifier (AV = 4)
–
1/2 LT1207
+
0.01µF
+
+
LT1207 • TA07
+
1/2 LT1207
–
1k
1k
V
V
OUT
IN
1k
–
–
1/2 LT1207
+
–
LT1207 • TA08
14
LT1207
U
TYPICAL APPLICATIO S
Paralleling Both CFAs for Guaranteed 500mA Output Drive Current
V
+
IN
3Ω
V
OUT
1/2 LT1207
–
1k
1k
+
3Ω
1/2 LT1207
–
1k
LT1207 • TA09
1k
U
PACKAGE DESCRIPTIO Dimensions in inches (millimeters) unless otherwise noted.
S Package
16-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.386 – 0.394*
(9.804 – 10.008)
16
15
14
13
12
11
10
9
0.150 – 0.157**
0.228 – 0.244
(3.810 – 3.988)
(5.791 – 6.197)
5
7
8
1
2
3
4
6
0.010 – 0.020
(0.254 – 0.508)
× 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)
0° – 8° TYP
0.050
(1.270)
TYP
0.014 – 0.019
(0.355 – 0.483)
0.016 – 0.050
0.406 – 1.270
S16 0695
*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
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-
tation that the interconnection of circuits as described herein will not infringe on existing patent rights.
15
LT1207
TYPICAL APPLICATION
U
CCD Clock Driver. Two 3rd Order Gaussian Filters Produce Clean CCD Clock Signals
45pF
CCD ARRAY LOAD
20V
1k
1k
1k
CLOCK
INPUT
CLK
74HC74
Q
Q
+
10Ω
1/2 LT1207
100pF
91pF
3300pF
D
–
0.01µF
1k
510Ω
45pF
1k
1k
1k
+
10Ω
1/2 LT1207
100pF
91pF
5
0
CLOCK
INPUT
–
3300pF
0.01µF
–10V
1k
15
0
LT1207 • TA10
DRIVER
OUTPUT
510Ω
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
Single Version of LT1207, 900V/µs Slew Rate, 0.02% Differential
Gain, 0.17° Differential Phase, with A = 2 and R = 30Ω, Stable with
LT1206
Single 250mA/60MHz Current Feedback Amplifier
V
L
C = 10,000pF, Shutdown Control Reduces Supply Current to 200µA
L
LT1210
Single 1A/30MHz Current Feedback Amplifier
Dual/Quad 100MHz Current Feedback Amplifiers
Higher Output Current Version of LT1206
LT1229/LT1230
Low Cost CFA for Video Applications, 1000V/µs Slew Rate, 30mA
Output Drive Current, 0.04% Differential Gain, 0.1° Differential
Phase, with A = 2 and R = 150Ω, 9.5mA Max Supply Current per
V
L
Op Amp, ±2V to ±15V Supply Range
LT1360/LT1361/LT1362
Single/Dual/Quad 50MHz, 800V/µs,
Fast Settling Voltage Feedback Amplifier, 60ns Settling Time to 0.1%,
10V Step, 5mA Max Supply Current per Op Amp, 9nV√Hz Input Noise
C-LoadTM Op Amps
Voltage, Drives All Capacitive Loads, 1mV Max V , 0.2% Differential
OS
Gain, 0.3° Differential Phase with A = 2 and R = 150Ω
V
L
C-Load is a trademark of Linear Technology Corporation
LT/GP 0196 10K • PRINTED IN USA
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
16
●
●
LINEAR TECHNOLOGY CORPORATION 1996
(408) 432-1900 FAX: (408) 434-0507 TELEX: 499-3977
相关型号：
LT1207CS#PBF
LT1207 - Dual 250mA/60MHz Current Feedback Amplifier; Package: SO; Pins: 16; Temperature Range: 0°C to 70°C
Linear
LT1207CS16
IC DUAL OP-AMP, 10000 uV OFFSET-MAX, 60 MHz BAND WIDTH, PDSO16, Operational Amplifier
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LT1208CS8#PBF
LT1208 - Dual and Quad 45MHz, 400V/µs Op Amps; Package: SO; Pins: 8; Temperature Range: 0°C to 70°C
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