LINER LT1207 Dual 250ma/60mhz current feedback amplifier Datasheet

LT1207
Dual 250mA/60MHz
Current Feedback Amplifier
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DESCRIPTIO
FEATURES
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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.
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
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APPLICATIO S
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ADSL/HDSL Drivers
Video Amplifiers
Cable Drivers
RGB Amplifiers
Test Equipment Amplifiers
Buffers
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.
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.
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TYPICAL APPLICATION
HDSL Driver
5V
+
0.1µF*
2.2µF**
+
VIN
SHDN A
1/2 LT1207
62Ω
–
L1
720Ω
15k
720Ω
240Ω
720Ω
–
15k
* CERAMIC
** TANTALUM
L1 = TRANSPOWER SMPT–308
OR SIMILAR DEVICE
62Ω
1/2 LT1207
+
–5V
0.1µF*
+
SHDN B
2.2µF**
1207 • TA01
1
LT1207
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RATI GS
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ABSOLUTE
PACKAGE/ORDER 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
ORDER PART
NUMBER
TOP VIEW
V+
16
1
V+
–IN A 2
15 OUT A
+IN A 3
14 V – A
LT1207CS
13 COMP A
SHDN A 4
–IN B 5
12 OUT B
+IN B 6
11 V – B
10 COMP B
SHDN B 7
V+ 8
9
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
VOS
Input Offset Voltage
TA = 25°C
MIN
TYP
MAX
UNITS
±3
±10
±15
mV
mV
●
Input Offset Voltage Drift
IIN+
Noninverting Input Current
TA = 25°C
±2
±5
±20
µA
µA
±10
±60
±100
µA
µA
●
IIN–
Inverting Input Current
TA = 25°C
●
en
Input Noise Voltage Density
f = 10kHz, RF = 1k, RG = 10Ω, RS = 0Ω
+ in
Input Noise Current Density
– in
Input Noise Current Density
RIN
Input Resistance
VIN = ±12V, VS = ±15V
VIN = ±2V, VS = ±5V
CIN
Input Capacitance
VS = ±15V
Input Voltage Range
VS = ±15V
VS = ±5V
●
●
Common Mode Rejection Ratio
VS = ±15V, VCM = ±12V
VS = ±5V, VCM = ±2V
●
●
Inverting Input Current
Common Mode Rejection
VS = ±15V, VCM = ±12V
VS = ±5V, VCM = ±2V
●
●
Power Supply Rejection Ratio
VS = ±5V to ±15V
●
CMRR
PSRR
2
µV/°C
10
●
3.6
nV/√Hz
f = 10kHz, RF = 1k, RG = 10Ω, RS = 10k
2
pA/√Hz
f = 10kHz, RF = 1k, RG = 10Ω, RS = 10k
30
pA/√Hz
10
5
MΩ
MΩ
2
pF
±12
±2
±13.5
±3.5
V
V
55
50
62
60
dB
dB
●
●
1.5
0.5
0.1
0.1
60
77
10
10
µA/V
µA/V
dB
LT1207
ELECTRICAL CHARACTERISTICS
VCM = 0, ±5V ≤ VS ≤ ±15V, pulse tested, VSHDN A = 0V, VSHDN B = 0V, unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
Noninverting Input Current
Power Supply Rejection
VS = ±5V to ±15V
Inverting Input Current
Power Supply Rejection
AV
MIN
TYP
MAX
UNITS
●
30
500
nA/V
VS = ±5V to ±15V
●
0.7
5
µA/V
Large-Signal Voltage Gain
VS = ±15V, VOUT = ±10V, RL = 50Ω
VS = ±5V, VOUT = ±2V, RL = 25Ω
●
●
55
55
71
68
dB
dB
ROL
Transresistance, ∆VOUT/∆IIN–
VS = ±15V, VOUT = ±10V, RL = 50Ω
VS = ±5V, VOUT = ±2V, RL = 25Ω
●
●
100
75
260
200
kΩ
kΩ
VOUT
Maximum Output Voltage Swing
VS = ±15V, RL = 50Ω, TA = 25°C
VS = ±5V, RL = 25Ω, TA = 25°C
●
±11.5
±10.0
±2.5
±2.0
●
250
●
IOUT
Maximum Output Current
RL = 1Ω
IS
Supply Current per Amplifier
VS = ±15V, VSHDN = 0V, TA = 25°C
Supply Current per Amplifier,
RSHDN = 51k (Note 4)
VS = ±15V, TA = 25°C
Positive Supply Current
per Amplifier, Shutdown
VS = ±15V, VSHDN A = 15V, VSHDN B = 15V
●
Output Leakage Current, Shutdown
VS = ±15V, VSHDN = 15V, VOUT = 0V
●
Slew Rate (Note 5)
AV = 2, TA = 25°C
±12.5
±3.0
500
1200
mA
20
30
35
mA
mA
12
17
mA
200
µA
●
SR
BW
V
V
V
V
10
400
900
µA
V/µs
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
Small-Signal Bandwidth
VS = ±15V, Peaking ≤ 0.5dB
RF = RG = 620Ω, RL = 100Ω
60
MHz
VS = ±15V, Peaking ≤ 0.5dB
RF = RG = 649Ω, RL = 50Ω
52
MHz
VS = ±15V, Peaking ≤ 0.5dB
RF = RG = 698Ω, RL = 30Ω
43
MHz
VS = ±15V, Peaking ≤ 0.5dB
RF = RG = 825Ω, RL = 10Ω
27
MHz
The ● denotes specifications which apply for 0°C ≤ TA ≤ 70°C.
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 θJA varies from 40°C/W to 60°C/W depending
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: RSHDN is connected between the Shutdown pin and ground.
Note 5: Slew rate is measured at ±5V on a ±10V output signal while
operating on ±15V supplies with RF = 1.5k, RG = 1.5k and RL = 400Ω.
Note 6: NTSC composite video with an output level of 2V.
3
LT1207
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S ALL-SIG AL BA DWIDTH
IS = 20mA per Amplifier Typical, Peaking ≤ 0.1dB
AV
RL
RF
VS = ±5V, RSHDN = 0Ω
–1
150
562
30
649
10
732
1
150
619
30
715
10
806
2
150
576
30
649
10
750
10
150
442
30
511
10
649
RG
562
649
732
–
–
–
576
649
750
48.7
56.2
71.5
– 3dB BW
(MHz)
48
34
22
54
36
22.4
48
35
22.4
40
31
20
– 0.1dB BW
(MHz)
21.4
17
12.5
22.3
17.5
11.5
20.7
18.1
11.7
19.2
16.5
10.2
AV
RL
RF
VS = ±15V, RSHDN = 0Ω
–1
150
681
30
768
10
887
1
150
768
30
909
10
1k
2
150
665
30
787
10
931
10
150
487
30
590
10
768
RG
– 3dB BW
(MHz)
– 0.1dB BW
(MHz)
681
768
887
–
–
–
665
787
931
536
64.9
84.5
50
35
24
66
37
23
55
36
22.5
44
33
20.7
19.2
17
12.3
22.4
17.5
12
23
18.5
11.8
20.7
17.5
10.8
RG
– 3dB BW
(MHz)
– 0.1dB BW
(MHz)
634
768
866
–
–
–
649
787
931
33.2
44.2
64.9
41
26.5
17
44
28
16.8
40
27
16.5
33
25
15.3
19.1
14
9.4
18.8
14.4
8.3
18.5
14.1
8.1
15.6
13.3
7.4
RG
– 3dB BW
(MHz)
– 0.1dB BW
(MHz)
IS = 10mA per Amplifier Typical, Peaking ≤ 0.1dB
AV
RL
RF
VS = ±5V, RSHDN = 10.2k
–1
150
576
30
681
10
750
1
150
665
30
768
10
845
2
150
590
30
681
10
768
10
150
301
30
392
10
499
RG
– 3dB BW
(MHz)
– 0.1dB BW
(MHz)
576
681
750
–
–
–
590
681
768
33.2
43.2
54.9
35
25
16.4
37
25
16.5
35
25
16.2
31
23
15
17
12.5
8.7
17.5
12.6
8.2
16.8
13.4
8.1
15.6
11.9
7.8
AV
RL
RF
VS = ±15V, RSHDN = 60.4k
–1
150
634
30
768
10
866
1
150
768
30
909
10
1k
2
150
649
30
787
10
931
10
150
301
30
402
10
590
IS = 5mA per Amplifier Typical, Peaking ≤ 0.1dB
AV
RL
RF
RG
– 3dB BW
(MHz)
– 0.1dB BW
(MHz)
VS = ±5V, RSHDN = 22.1k
AV
RL
RF
VS = ±15V, RSHDN = 121k
–1
150
30
10
604
715
681
604
715
681
21
14.6
10.5
10.5
7.4
6.0
–1
150
30
10
619
787
825
619
787
825
25
15.8
10.5
12.5
8.5
5.4
1
150
30
10
768
866
825
–
–
–
20
14.1
9.8
9.6
6.7
5.1
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
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TYPICAL PERFOR A CE CHARACTERISTICS
–3dB BANDWIDTH (MHz)
80
RF = 470Ω
70
RF = 560Ω
60
RF = 680Ω
50
40
RF = 750Ω
30
RF = 1k
20
10
AV = 2
RL = 10Ω
40
RF = 560Ω
30
RF = 750Ω
20
RF = 1k
RF = 2k
10
1k
FEEDBACK RESISTOR
AV = 2
RL = ∞
VS = ±15V
CCOMP = 0.01µF
10
RF = 1.5k
100
0
0
4
14
12
10
8
SUPPLY VOLTAGE (±V)
6
16
4
18
14
12
10
8
SUPPLY VOLTAGE (±V)
6
16
1
18
Bandwidth vs Supply Voltage
Bandwidth and Feedback Resistance
vs Capacitive Load for 5dB Peak
50
70
RF =390Ω
RF = 330Ω
50
40
RF = 470Ω
30
RF = 680Ω
20
10
100
AV = 10
RL = 10Ω
BANDWIDTH
40
30
RF = 560Ω
20
RF = 680Ω
RF = 1k
10
RF = 1.5k
1k
10
FEEDBACK RESISTOR
RF = 1.5k
0
0
4
14
12
10
8
SUPPLY VOLTAGE (±V)
6
16
0
100
4
18
14
12
10
8
SUPPLY VOLTAGE (±V)
6
16
18
1
Differential Phase
vs Supply Voltage
Spot Noise Voltage and Current
vs Frequency
100
0.10
RF = RG = 560Ω
AV = 2
N PACKAGE
0.20
RL = 30Ω
RL = 50Ω
0.10
RL = 15Ω
0.08
DIFFERENTIAL GAIN (%)
0.30
RF = RG = 560Ω
AV = 2
N PACKAGE
SPOT NOISE (nV/√Hz OR pA/√Hz)
RL = 15Ω
0.06
RL = 30Ω
0.04
RL = 50Ω
0.02
RL = 150Ω
0
7
11
13
9
SUPPLY VOLTAGE (±V)
15
LT1207 • TPC07
–in
10
en
in
RL = 150Ω
0
5
1
10k
LT1207 • TPC06
Differential Gain
vs Supply Voltage
0.50
0.40
10
100
1k
CAPACITIVE LOAD (pF)
LT1207 • TPC05
LT1207 • TPC04
AV = +2
RL = ∞
VS = ±15V
CCOMP = 0.01µF
–3dB BANDWIDTH (MHz)
– 3dB BANDWIDTH (MHz)
80
60
10k
PEAKING ≤ 0.5dB
PEAKING ≤ 5dB
AV = 10
RL = 100Ω
FEEDBACK RESISTOR (Ω)
PEAKING ≤ 0.5dB
PEAKING ≤ 5dB
1
10000
LT1207 • TPC03
Bandwidth vs Supply Voltage
100
90
100
10
1000
CAPACITIVE LOAD (pF)
LT1207 • TPC02
LT1207 • TPC01
–3dB BANDWIDTH (MHz)
BANDWIDTH
–3dB BANDWIDTH (MHz)
– 3dB BANDWIDTH (MHz)
90
PEAKING ≤ 0.5dB
PEAKING ≤ 5dB
AV = 2
RL = 100Ω
FEEDBACK RESISTOR (Ω)
PEAKING ≤ 0.5dB
PEAKING ≤ 5dB
100
10k
50
100
DIFFERENTIAL PHASE (DEG)
Bandwidth and Feedback Resistance
vs Capacitive Load for 0.5dB Peak
Bandwidth vs Supply Voltage
Bandwidth vs Supply Voltage
5
7
11
13
9
SUPPLY VOLTAGE (±V)
15
LT1207 • TPC08
1
10
100
1k
10k
FREQUENCY (Hz)
100k
LT1207 • TPC09
5
LT1207
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TYPICAL PERFOR A CE CHARACTERISTICS
Supply Current vs
Ambient Temperature, VS = ±5V
Supply Current vs Supply Voltage
25
25
22
TJ = –40˚C
20
TJ = 25˚C
18
16
TJ = 85˚C
14
TJ = 125˚C
12
10
4
16
14
12
10
8
SUPPLY VOLTAGE (±V)
6
RSD = 0Ω
20
15
RSD = 10.2k
10
RSD = 22.1k
5
0
–50 –25
18
AV = 1
RL = ∞
50
25
0
75
TEMPERATURE (°C)
10
8
6
4
–1.0
–1.5
–2.0
2.0
1.5
1.0
0.5
2
100
300
400
200
SHUTDOWN PIN CURRENT (µA)
V–
–50
500
–25
4
RL = 50Ω
RL = 2k
1
V–
–50
–25
0
25
50
75
TEMPERATURE (°C)
100
125
LT1207 • TPC16
6
0.6
SINKING
0.5
0.4
50
25
75
0
TEMPERATURE (°C)
60
50
125
Supply Current vs Large-Signal
Output Frequency (No Load)
60
NEGATIVE
RL = 50Ω
VS = ±15V
RF = RG = 1k
POSITIVE
40
30
20
10
0
10k
100
LT1207 • TPC15
100k
1M
10M
FREQUENCY (Hz)
100M
LT1207 • TPC17
SUPPLY CURRENT PER AMPLIFIER (mA)
POWER SUPPLY REJECTION (dB)
OUTPUT SATURATION VOLTAGE (V)
–4
2
SOURCING
0.7
0.3
–50 –25
125
70
RL = 2k
–3
125
0.8
Power Supply Rejection Ratio
vs Frequency
RL = 50Ω
100
0.9
LT1207 • TPC14
Output Saturation Voltage
vs Junction Temperature
3
100
0
25
50
75
TEMPERATURE (°C)
LT1207 • TPC13
–2
50
25
0
75
TEMPERATURE (°C)
1.0
OUTPUT SHORT-CIRCUIT CURRENT (A)
COMMON MODE RANGE (V)
SUPPLY CURRENT PER AMPLIFIER (mA)
12
–1
RSD = 121k
5
Output Short-Circuit Current
vs Junction Temperature
– 0.5
14
VS = ±15V
RSD = 60.4k
10
LT1207 • TPC12
V+
VS = ±15V
16
V+
15
Input Common Mode Limit
vs Junction Temperature
20
0
20
LT1207 • TPC11
Supply Current
vs Shutdown Pin Current
18
AV = 1
RL = ∞
RSD = 0Ω
0
–50 –25
125
100
LT1207 • TPC10
0
SUPPLY CURRENT PER AMPLIFIER (mA)
VSHDN = 0V
SUPPLY CURRENT PER AMPLIFIER (mA)
SUPPLY CURRENT PER AMPLIFIER (mA)
24
Supply Current vs
Ambient Temperature, VS = ±15V
50
AV = 2
RL = ∞
VS = ±15V
VOUT = 20VP-P
40
30
20
10
10k
100k
1M
10M
FREQUENCY (Hz)
LT1207 • TPC18
LT1207
W U
TYPICAL PERFOR A CE CHARACTERISTICS
Output Impedance in Shutdown
vs Frequency
Output Impedance vs Frequency
AV = 1
RF = 1k
VS = ±15V
RSHDN = 121k
RSHDN = 0Ω
1
0.1
VS = ±15V
VO = 2VP-P
–40
2nd
RL = 10Ω
10k
DISTORTION (dBc)
10
–30
100k
VS = ±15V
IO = 0mA
OUTPUT IMPEDANCE (Ω)
OUTPUT IMPEDANCE (Ω)
100
2nd and 3rd Harmonic Distortion
vs Frequency
1k
–50
3rd
2nd
–60
–70
RL = 30Ω
3rd
100
–80
1M
10M
100M
–90
10
100k
1M
FREQUENCY (Hz)
10M
100M
3
2
4 5
FREQUENCY (MHz)
1
FREQUENCY (Hz)
LT1207 • TPC19
Test Circuit for 3rd Order Intercept
VS = ±15V
RL = 50Ω
RF = 590Ω
RG = 64.9Ω
50
6 7 8 9 10
LT1207 • TPC21
LT1207 • TPC20
3rd Order Intercept vs Frequency
60
3rd ORDER INTERCEPT (dBm)
0.01
100k
+
PO
1/2 LT1207
–
40
590Ω
30
50Ω
65Ω
MEASURE INTERCEPT AT PO
LT1207 • TPC23
20
10
0
5
10
15
20
FREQUENCY (MHz)
25
30
LT1207 • TPC22
7
LT1207
W
W
SI PLIFIED SCHE ATIC
V+
TO ALL
CURRENT
SOURCES
Q5
Q10
Q2
Q18
D1
Q6
Q1
Q17
Q11
Q15
Q9
V–
1.25k
+IN
CC
–IN
V–
50Ω
COMP
RC
OUTPUT
V+
SHUTDOWN
V+
Q12
Q3
Q8
Q16
Q14
D2
Q4
Q7
Q13
V–
1/2 LT1207 CURRENT FEEDBACK AMPLIFIER
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W
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APPLICATI
LT1207 • SS
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
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
8
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.
LT1207
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VS = ±15V
10
RF = 1.2k
COMPENSATION
8
VOLTAGE GAIN (dB)
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APPLICATI
6
4
RF = 2k
NO COMPENSATION
2
0
RF = 2k
COMPENSATION
–2
–4
–6
–8
1
10
FREQUENCY (MHz)
100
LT1207 • F01
Figure 1.
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.
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.
15V
VOUT
1/2 LT1207
SHDN
–
–15V
RF
15V
5V
RG
24k
ENABLE
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.
74C906
LT1207 • F02
Figure 2. Shutdown Interface
VOUT
Shutdown/Current Set
+
VIN
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.
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
ENABLE
If the shutdown feature is not used, the Shutdown pins
must be connected to ground or V –.
AV = 1
RF = 825Ω
RL = 50Ω
RPU = 24k
VIN = 1VP-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
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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
RL = 50Ω
IQ = 5mA, 10mA, 20mA
VS = ±15V
LT1207 • F04a
Figure 4a. Large-Signal Response vs IQ, AV = –1
RF = 825Ω
RL = 50Ω
VS = ±15V
LT1207 • F05a
Figure 5a. Large-Signal Response, AV = 1
RF = 750Ω
RL = 50Ω
IQ = 5mA, 10mA, 20mA
VS = ±15V
LT1207 • F04b
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,
10
RF = RG = 750Ω
RL = 50Ω
VS = ±15V
LT1207 • F05b
Figure 5b. Large-Signal Response, AV = –1
LT1207
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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
LT1207 • F05c
RF = 750Ω
RL = 50Ω
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.
VS = ±15V
RF = RG = 3k
RL = ∞
LT1207 • F06
Figure 6. Large-Signal Response, CL = 10,000pF
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.
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 mismatch. 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.
Thermal Considerations
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
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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
TOTAL
THERMAL RESISTANCE
COPPER AREA (JUNCTION-TO-AMBIENT)
BACKSIDE
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
THERMAL RESISTANCE (°C/W)
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.
15V
I
37.5mA
+
330Ω
12V
1/2 LT1207
SHDN
–
1k
–15V
–12V
f = 2MHz
0.01µF
200pF
1k
LT1206 • F07
Figure 8. Thermal Calculation Example
The dissipation for each amplifier is:
70
PD = (37.5mA)(30V) – (12V)2/(1k||1k) = 0.837W
60
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:
50
40
30
TJ = (1.674W)(40°C/W) + 70°C = 137°C
20
10
0
0
1000
3000
4000
2000
COPPER AREA (mm2)
5000
LT1207 • F07
Figure 7. Thermal Resistance vs Total Copper Area
(Top + Bottom)
Calculating Junction Temperature
The junction temperature can be calculated from the
equation:
TJ = (PD)(θJA) + TA
12
where:
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 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.
LT1207
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TYPICAL APPLICATIO S
Gain of Eleven High Current Amplifier
+
1/2 LT1207
+
LT1097
–
–
OUT
COMP
SHDN
0.01µF
500pF
330Ω
3k
10k
LT1207 • TA02
OUTPUT OFFSET: < 500µV
SLEW RATE: 2V/µs
BANDWIDTH: 4MHz
STABLE WITH CL < 10nF
1k
Gain of Ten Buffered Line Driver
15V 1µF
15V 1µF
+
+
+
+
LT1115
–
1µF
1/2 LT1207
SHDN
+
–
OUTPUT
0.01µF
RL
–15V
1µF
68pF
+
VIN
–15V
560Ω
560Ω
909Ω
LT1207 • TA03
100Ω
RL = 32Ω
VO = 5VRMS
THD + NOISE = 0.0009% AT 1kHz
= 0.004% AT 20kHz
SMALL-SIGNAL 0.1dB BANDWIDTH = 600kHz
13
LT1207
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CMOS Logic to Shutdown Interface
Distribution Amplifier
15V
+
VIN
75Ω
+
24k
1/2 LT1207
SHDN
75Ω
1/2 LT1207
SHDN
–
75Ω CABLE
75Ω
RF
75Ω
–
LT1207 • TA05
LT1207 • TA04
5V
RG
–15V
75Ω
10k
2N3904
Buffer AV = 1
VIN
+
–
Differential Output Driver
1/2 LT1207
VIN
*OPTIONAL, USE WITH CAPACITIVE LOADS
**VALUE OF RF DEPENDS ON SUPPLY
VOLTAGE AND LOADING. SELECT
FROM TYPICAL AC PERFORMANCE
TABLE OR DETERMINE EMPIRICALLY
VOUT
COMP
SHDN
0.01µF*
+
1/2 LT1207
–
+
0.01µF
1k
RF**
LT1207 • TA06
500Ω
VOUT
1k
1k
Differential Input—Differential Output Power Amplifier (AV = 4)
–
1/2 LT1207
–
+
0.01µF
+
+
1/2 LT1207
+
–
1k
VIN
VOUT
1k
1k
–
1/2 LT1207
–
–
+
LT1207 • TA08
14
LT1207 • TA07
LT1207
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TYPICAL APPLICATIO S
Paralleling Both CFAs for Guaranteed 500mA Output Drive Current
+
VIN
3Ω
VOUT
1/2 LT1207
–
1k
1k
+
3Ω
1/2 LT1207
–
1k
LT1207 • TA09
1k
PACKAGE DESCRIPTIO
U
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**
(3.810 – 3.988)
0.228 – 0.244
(5.791 – 6.197)
1
0.010 – 0.020
× 45°
(0.254 – 0.508)
0.008 – 0.010
(0.203 – 0.254)
2
3
4
5
6
0.053 – 0.069
(1.346 – 1.752)
0.014 – 0.019
(0.355 – 0.483)
8
0.004 – 0.010
(0.101 – 0.254)
0° – 8° TYP
0.016 – 0.050
0.406 – 1.270
7
0.050
(1.270)
TYP
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 representation that the interconnection of circuits as described herein will not infringe on existing patent rights.
15
LT1207
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TYPICAL APPLICATION
CCD Clock Driver. Two 3rd Order Gaussian Filters Produce Clean CCD Clock Signals
45pF
CCD ARRAY LOAD
20V
1k
CLOCK
INPUT
CLK
1k
+
Q
74HC74
D
1k
100pF
91pF
Q
10Ω
1/2 LT1207
3300pF
–
1k
0.01µF
510Ω
45pF
1k
1k
1k
100pF
CLOCK 5
INPUT 0
+
91pF
10Ω
1/2 LT1207
–
3300pF
0.01µF
–10V
1k
15
LT1207 • TA10
DRIVER
OUTPUT
510Ω
0
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LT1206
Single 250mA/60MHz Current Feedback Amplifier
Single Version of LT1207, 900V/µs Slew Rate, 0.02% Differential
Gain, 0.17° Differential Phase, with AV = 2 and RL = 30Ω, Stable with
CL = 10,000pF, Shutdown Control Reduces Supply Current to 200µA
LT1210
Single 1A/30MHz Current Feedback Amplifier
Higher Output Current Version of LT1206
LT1229/LT1230
Dual/Quad 100MHz Current Feedback Amplifiers
Low Cost CFA for Video Applications, 1000V/µs Slew Rate, 30mA
Output Drive Current, 0.04% Differential Gain, 0.1° Differential
Phase, with AV = 2 and RL = 150Ω, 9.5mA Max Supply Current per
Op Amp, ±2V to ±15V Supply Range
LT1360/LT1361/LT1362
Single/Dual/Quad 50MHz, 800V/µs,
C-LoadTM Op Amps
Fast Settling Voltage Feedback Amplifier, 60ns Settling Time to 0.1%,
10V Step, 5mA Max Supply Current per Op Amp, 9nV√Hz Input Noise
Voltage, Drives All Capacitive Loads, 1mV Max VOS, 0.2% Differential
Gain, 0.3° Differential Phase with AV = 2 and RL = 150Ω
C-Load is a trademark of Linear Technology Corporation
16
Linear Technology Corporation
LT/GP 0196 10K • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● TELEX: 499-3977
 LINEAR TECHNOLOGY CORPORATION 1996