LT1395 [Linear]
Single/Dual/Quad 400MHz Current Feedback Amplifier; 单/双/四核400MHz的电流反馈放大器
| 型号： | LT1395 |
| 厂家： | 
Linear |
| 描述： | Single/Dual/Quad 400MHz Current Feedback Amplifier |
| 文件： | 总12页 (文件大小：200K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LT1395/ LT1396/ LT1397
Sing le / Dua l/ Qua d 400MHz
Curre nt Fe e d b a c k Am p lifie r
U
FEATURES
DESCRIPTIO
The LT®1395/LT1396/LT1397 are single/dual/quad
400MHzcurrentfeedbackamplifiers withan800V/µs slew
rate and the ability to drive up to 80mA of output current.
■
400MHz Bandwidth on ±5V (AV = 1)
350MHz Bandwidth on ±5V (AV = 2, –1)
0.1dB Gain Flatness: 100MHz (AV = 1, 2 and –1)
High Slew Rate: 800V/µs
Wide Supply Range: ±2V(4V) to ±6V(12V)
80mA Output Current
Low Supply Current: 4.6mA/Amplifier
LT1395: SO-8 Package
■
■
■
The LT1395/LT1396/LT1397 operate on all supplies from
a single 4V to ±6V. At ±5V, they draw 4.6mA of supply
current per amplifier.
■
■
■
■
The LT1395/LT1396/LT1397 are manufactured on Linear
Technology’s proprietarycomplementarybipolarprocess.
They have standard single/dual/quad pinouts and they are
optimized for use on supply voltages of ±5V.
LT1396: SO-8 and MSOP Packages
LT1397: SO-14 and SSOP-16 Packages
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, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
■
Cable Drivers
Video Amplifiers
MUX Amplifiers
High Speed Portable Equipment
■
■
■
■
IF Amplifiers
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TYPICAL APPLICATIO
Unity-Gain Video Loop-Through Amplifier
Loop-Through Amplifier
Frequency Response
R
63.4Ω
R
R
R
F2
G2
G1
F1
10
1.02k
255Ω
255Ω
0
NORMAL SIGNAL
–10
–
–
1/2
LT1396
1/2
LT1396
–20
V
OUT
V
+
V
–
3.01k
3.01k
IN
IN
+
+
–30
–40
1% RESISTORS
FOR A GAIN OF G:
= G (V – V )
–
IN
0.67pF
12.1k
0.67pF
12.1k
COMMON MODE SIGNAL
V
+
OUT
IN
–50
–60
R
R
= R
F2
= (G + 3) R
F1
G1
F2
100 1k
10k 100k 1M 10M 100M 1G
FREQUENCY (Hz)
R
F2
BNC INPUTS
R
=
G2
G + 3
TRIM CMRR WITH R
HIGH INPUT RESISTANCE DOES NOT LOAD CABLE
EVEN WHEN POWER IS OFF
1395/6/7 TA02
G1
1395/6/7 TA01
1
LT1395/ LT1396/ LT1397
W W W
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(Note 1)
ABSOLUTE AXI U RATI GS
Total Supply Voltage (V+ to V–) ........................... 12.6V Operating Temperature Range (Note 4) . –40°C to 85°C
Input Current (Note 2) ....................................... ±10mA Specified Temperature Range (Note 5).. –40°C to 85°C
Output Current................................................. ±100mA Storage Temperature Range ................ –65°C to 150°C
Differential Input Voltage (Note 2) ........................... ±5V Junction Temperature (Note 6)............................ 150°C
Output Short-Circuit Duration (Note 3)........ Continuous
Lead Temperature (Soldering, 10 sec)................. 300°C
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/O
PACKAGE RDER I FOR ATIO
TOP VIEW
TOP VIEW
TOP VIEW
+
OUT A 1
–IN A 2
8 V
7 OUT B
6
5
+
V
NC
–IN
+IN
1
2
3
4
8
7
6
5
NC
OUT A
–IN A
+IN A
1
2
3
4
8
7
6
5
–
+
+
V
+IN A 3
–
–IN A
+IN B
–
+
OUT B
–IN A
+IN B
–
+
–
+
V
4
OUT
NC
–
+
MS8 PACKAGE
–
V
–
V
8-LEAD PLASTIC MSOP
S8 PACKAGE
8-LEAD PLASTIC SO
S8 PACKAGE
8-LEAD PLASTIC SO
TJMAX = 150°C, θJA = 150°C/W
TJMAX = 150°C, θJA = 250°C/W
TJMAX = 150°C, θJA = 150°C/W
ORDER PART NUMBER
LT1395CS8
ORDER PART NUMBER
LT1396CMS8
ORDER PART NUMBER
LT1396CS8
S8 PART MARKING
1395
MS8 PART MARKING
LTDY
S8 PART MARKING
1396
TOP VIEW
TOP VIEW
1
2
3
4
5
6
7
8
OUT D
–IN D
+IN D
1
2
3
4
5
6
7
14
13
12
11
10
9
16
15
14
13
12
11
10
9
OUT A
–IN A
+IN A
OUT D
–IN D
+IN D
OUT A
–IN A
+IN A
–
+
–
+
–
+
–
+
–
+
–
+
V
V
V
V
+IN C
–IN C
OUT C
NC
+IN B
–IN B
OUT B
+IN C
–IN C
OUT C
+IN B
–IN B
OUT B
NC
+
–
+
–
+
–
+
–
8
S PACKAGE
14-LEAD PLASTIC SO
GN PACKAGE
16-LEAD PLASTIC SSOP
TJMAX = 150°C, θJA = 100°C/W
TJMAX = 150°C, θJA = 135°C/W
ORDER PART NUMBER
LT1397CS
ORDER PART NUMBER
LT1397CGN
GN PART MARKING
1397
Consult factory for Industrial and Military grade parts.
2
LT1395/ LT1396/ LT1397
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the specified operating temperature range, otherwise specifications are at TA = 25°C.
For each amplifier: VCM = 0V, V = ±5V, pulse tested, unless otherwise noted. (Note 5)
S
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
Input Offset Voltage
1
±10
±12
mV
mV
OS
●
●
∆V /∆T
Input Offset Voltage Drift
Noninverting Input Current
15
10
µV/°C
OS
+
I
IN
±25
±30
µA
µA
●
●
–
I
IN
Inverting Input Current
10
±50
±60
µA
µA
e
Input Noise Voltage Density
Noninverting Input Noise Current Density
Inverting Input Noise Current Density
Input Resistance
f = 1kHz, R = 1k, R = 10Ω, R = 0Ω
4.5
6
nV/√Hz
pA/√Hz
pA/√Hz
MΩ
n
F
G
S
+i
f = 1kHz
f = 1kHz
n
–i
25
1
n
R
V
IN
= ±3.5V
●
0.3
3.5
IN
C
Input Capacitance
2.0
pF
IN
V
Input Voltage Range, High
V = ±5V
●
●
4.0
4.0
V
V
INH
S
V = 5V, 0V
S
V
Input Voltage Range, Low
Output Voltage Swing, High
V = ±5V
–4.0
1.0
–3.5
V
V
INL
S
V = 5V, 0V
S
V
V = ±5V
3.9
3.7
4.2
V
V
V
OUTH
S
V = ±5V
●
●
●
S
V = 5V, 0V
S
4.2
V
Output Voltage Swing, Low
Output Voltage Swing, High
Output Voltage Swing, Low
Common Mode Rejection Ratio
V = ±5V
–4.2
–3.9
–3.7
V
V
V
OUTL
S
V = ±5V
S
V = 5V, 0V
S
0.8
3.6
V
V = ±5V, R = 150Ω
3.4
3.2
V
V
V
OUTH
S
L
V = ±5V, R = 150Ω
S
L
V = 5V, 0V; R = 150Ω
3.6
S
L
V
V = ±5V, R = 150Ω
–3.6
–3.4
–3.2
V
V
V
OUTL
S
L
V = ±5V, R = 150Ω
●
●
S
L
V = 5V, 0V; R = 150Ω
0.6
52
10
S
L
CMRR
V
CM
= ±3.5V
42
56
dB
–I
Inverting Input Current
Common Mode Rejection
V
V
CM
= ±3.5V
= ±3.5V
16
22
µA/V
µA/V
CMRR
CM
●
●
PSRR
+I
Power Supply Rejection Ratio
V = ±2V to ±5V
S
70
1
dB
Noninverting Input Current
Power Supply Rejection
V = ±2V to ±5V
S
2
3
µA/V
µA/V
PSRR
●
●
–I
Inverting Input Current
Power Supply Rejection
V = ±2V to ±5V
S
2
7
µA/V
PSRR
A
Large-Signal Voltage Gain
V
= ±2V, R = 150Ω
50
40
80
65
dB
kΩ
V
OUT
L
–
R
OL
Transimpedance, ∆V /∆I
V
OUT
= ±2V, R = 150Ω
100
OUT IN
L
I
Maximum Output Current
Supply Current per Amplifier
Slew Rate (Note 7)
R = 0Ω
L
●
●
mA
mA
V/µs
OUT
I
S
4.6
6.5
SR
A = –1, R = 150Ω
V
500
800
L
–3dB BW
–3dB Bandwidth
A = 1, R = 374Ω, R = 100Ω
400
300
MHz
MHz
V
F
L
A = 2, R = R = 255Ω, R = 100Ω
V
F
G
L
0.1dB BW
0.1dB Bandwidth
A = 1, R = 374Ω, R = 100Ω
100
100
MHz
MHz
V
F
L
A = 2, R = R = 255Ω, R = 100Ω
V
F
G
L
3
LT1395/ LT1396/ LT1397
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the specified operating temperature range, otherwise specifications are at TA = 25°C.
For each amplifier: VCM = 0V, V = ±5V, pulse tested, unless otherwise noted. (Note 5)
S
SYMBOL
t , t
PARAMETER
CONDITIONS
R = R = 255Ω, R = 100Ω, V = 1V
P-P
MIN
TYP
1.3
MAX
UNITS
ns
Small-Signal Rise and Fall Time
Propagation Delay
r
f
F
G
L
OUT
t
R = R = 255Ω, R = 100Ω, V = 1V
P-P
2.5
ns
PD
F
G
L
OUT
os
Small-Signal Overshoot
Settling Time
R = R = 255Ω, R = 100Ω, V = 1V
P-P
10
%
F
G
L
OUT
t
0.1%, A = –1, R = R = 280Ω, R = 150Ω
25
ns
S
V
F
G
L
dG
dP
Differential Gain (Note 8)
Differential Phase (Note 8)
R = R = 255Ω, R = 150Ω
0.02
0.04
%
F
G
L
R = R = 255Ω, R = 150Ω
DEG
F
G
L
Note 1: Absolute Maximum Ratings are those values beyond which the life
Note 6: T is calculated from the ambient temperature TA and the
J
of a device may be impaired.
power dissipation PD according to the following formula:
Note 2: This parameter is guaranteed to meet specified performance
LT1395CS8: T = TA + (PD • 150°C/W)
J
through design and characterization. It has not been tested.
LT1396CS8: T = TA + (PD • 150°C/W)
J
Note 3: A heat sink may be required depending on the power supply
voltage and how many amplifiers have their outputs short circuited.
LT1396CMS8: T = TA + (PD • 250°C/W)
J
LT1397CS14: T = TA + (PD • 100°C/W)
J
Note 4: The LT1395C/LT1396C/LT1397C are guaranteed functional over
the operating temperature range of –40°C to 85°C.
LT1397CGN16: T = TA + (PD • 135°C/W)
J
Note 7: Slew rate is measured at ±2V on a ±3V output signal.
Note 5: The LT1395C/LT1396C/LT1397C are guaranteed to meet specified
performance from 0°C to 70°C. The LT1395C/LT1396C/LT1397C are
designed, characterized and expected to meet specified performance from
–40°C and 85°C but is not tested or QA sampled at these temperatures.
For guaranteed I-grade parts, consult the factory.
Note 8: Differential gain and phase are measured using a Tektronix
TSG120YC/NTSC signal generator and a Tektronix 1780R Video
Measurement Set. The resolution of this equipment is 0.1% and 0.1°.
Ten identical amplifier stages were cascaded giving an effective
resolution of 0.01% and 0.01°.
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TYPICAL AC PERFOR A CE
SMALL SIGNAL
–3dB BW (MHz)
SMALL SIGNAL
0.1dB BW (MHz)
SMALL SIGNAL
PEAKING (dB)
V (V)
S
A
V
R (Ω)
L
R (Ω)
F
R (Ω)
G
±5
±5
±5
1
2
100
100
100
374
255
280
–
400
350
350
100
100
100
0.1
0.1
0.1
255
280
–1
U W
TYPICALPERFOR A CE CHARACTERISTICS
Closed-Loop Gain vs Frequency
(AV = 1)
Closed-Loop Gain vs Frequency
(AV = 2)
Closed-Loop Gain vs Frequency
(AV = –1)
0
–2
–4
–6
0
–2
–4
–6
6
4
2
0
1M
10M
100M
1G
1M
10M
100M
1G
1M
10M
100M
1G
1397 G01
V = ±5V
S
V = ±5V
S
FREQUENCY (Hz)
V = ±5V
S
FREQUENCY (Hz)
FREQUENCY (Hz)
1397 G03
1397 G02
VIN = –10dBm
VIN = –10dBm
VIN = –10dBm
RF = RG = 255Ω
RL = 100Ω
RF = 374Ω
RL = 100Ω
RF = RG = 280Ω
RL = 100Ω
4
LT1395/ LT1396/ LT1397
U W
TYPICALPERFOR A CE CHARACTERISTICS
Large-Signal Transient Response
(AV = 1)
Large-Signal Transient Response
(AV = 2)
Large-Signal Transient Response
(AV = –1)
1395/6/7 G04
1395/6/7 G05
1395/6/7 G06
V = ±5V
S
TIME (10ns/DIV)
V = ±5V
S
TIME (10ns/DIV)
V = ±5V
S
TIME (10ns/DIV)
VIN = ±2.5V
VIN = ±1.25V
VIN = ±2.5V
RF = 374Ω
RL = 100Ω
RF = RG = 255Ω
RL = 100Ω
RF = RG = 280Ω
RL = 100Ω
2nd and 3rd Harmonic Distortion
vs Frequency
Maximum Undistorted Output
Voltage vs Frequency
PSRR vs Frequency
8
7
6
5
4
3
2
80
70
60
50
40
30
20
10
0
30
40
T = 25°C
A
R = R = 255Ω
F
G
R = 100Ω
L
A = +1
A = +2
V
V = ±5V
V
S
50
V
OUT
= 2VPP
+PSRR
–PSRR
60
70
HD3
HD2
80
T
= 25°C
A
90
R = 374Ω (A = 1)
T = 25°C
F V
A
R = R = 255Ω (A = 2)
R = R = 255Ω
F
L
G
V
F
G
R
= 100Ω
R = 100Ω
100
110
L
V = ±5V
S
A = +2
V
1M
10M
FREQUENCY (Hz)
100M
10k
100k
1M
10M
100M
1k
10k
100k
1M
10M 100M
FREQUENCY (Hz)
FREQUENCY (Hz)
1397 G09
1397 G08
1397 G07
Input Voltage Noise and Current
Noise vs Frequency
Maximum Capacitive Load
vs Feedback Resistor
Output Impedance vs Frequency
1000
100
100
10
1000
100
10
R = R = 255Ω
F
G
R = 50Ω
L
A = +2
V
V = ±5V
S
1
–i
n
+i
n
10
1
0.1
0.01
e
R = R
n
F
G
A = +2
V
V = ±5V
S
PEAKING ≤ 5dB
2100 2700 3300
FEEDBACK RESISTANCE (Ω)
1
10 30 100 300 1k 3k 10k 30k 100k
FREQUENCY (Hz)
300
900
1500
10k
100k
1M
10M
100M
FREQUENCY (Hz)
1397 G11
1397 G10
1397 G13
5
LT1395/ LT1396/ LT1397
U W
TYPICALPERFOR A CE CHARACTERISTICS
Capacitive Load
vs Output Series Resistor
Output Voltage Swing
vs Temperature
Supply Current vs Supply Voltage
40
30
20
10
0
5
4
6
5
R = R = 255Ω
F
G
V = ±5V
S
OVERSHOOT < 2%
R = 100k
R = 150Ω
L
3
L
2
4
1
3
2
V = ±5V
S
0
–1
–2
–3
–4
–5
R = 100k
L
R = 150Ω
L
1
0
10
100
CAPACITIVE LOAD (pF)
1000
0
1
2
3
4
5
6
7
8
9
–50
0
25
50
75
125
–25
100
SUPPLY VOLTAGE (±V)
AMBIENT TEMPERATURE (°C)
1397 G14
1397 G15
1397 G16
Input Bias Currents
vs Temperature
Positive Supply Current per
Amplifier vs Temperature
Input Offset Voltage
vs Temperature
15
12
9
3.0
2.5
2.0
1.5
1.0
0.5
0
5.00
4.95
4.90
4.85
4.80
4.75
4.70
4.65
4.60
4.55
4.50
V = ±5V
S
V = ±5V
V = ±5V
S
S
+
I
B
–
I
B
6
3
–0.5
–1.0
0
50
100 125
–50 –25
0
25
75
–25
0
50
75 100 125
–25
0
50
75 100 125
–50
25
–50
25
AMBIENT TEMPERATURE (°C)
AMBIENT TEMPERATURE (°C)
AMBIENT TEMPERATURE (°C)
1397 G19
1397 G17
1397 G18
Square Wave Response
Propagation Delay
Rise Time and Overshoot
OS = 10%
1395/6/7 G22
RL = 100Ω
TIME (10ns/DIV)
RF = RG = 255Ω
f = 10MHz
1395/6/7 G20
1395/6/7 G21
tPD = 2.5ns
tr = 1.3ns
AV = +2
TIME (500ps/DIV)
A = +2
V
TIME (500ps/DIV)
RL = 100Ω
RF = RG = 255Ω
RL = 100Ω
RF = RG = 255Ω
6
LT1395/ LT1396/ LT1397
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PIN FUNCTIONS
LT1395CS8
OUT B (Pin 7): B Channel Output.
NC (Pin 1): No Connection.
–IN (Pin 2): Inverting Input.
+IN (Pin 3): Noninverting Input.
OUT C (Pin 8): C Channel Output.
–IN C (Pin 9): Inverting Input of C Channel Amplifier.
+IN C (Pin 10):Noninverting Input of C Channel Amplifier.
V– (Pin 11): Negative Supply Voltage, Usually –5V.
+IND(Pin12):NoninvertingInputofDChannelAmplifier.
–IN D (Pin 13): Inverting Input of D Channel Amplifier.
OUT D (Pin 14): D Channel Output.
V– (Pin 4): Negative Supply Voltage, Usually –5V.
NC (Pin 5): No Connection.
OUT (Pin 6): Output.
V+ (Pin 7): Positive Supply Voltage, Usually 5V.
NC (Pin 8): No Connection.
LT1397CGN
LT1396CMS8, LT1396CS8
OUT A (Pin 1): A Channel Output.
OUT A (Pin 1): A Channel Output.
–IN A (Pin 2): Inverting Input of A Channel Amplifier.
+IN A (Pin 3): Noninverting Input of A Channel Amplifier.
V+ (Pin 4): Positive Supply Voltage, Usually 5V.
+IN B (Pin 5): Noninverting Input of B Channel Amplifier.
–IN B (Pin 6): Inverting Input of B Channel Amplifier.
OUT B (Pin 7): B Channel Output.
–IN A (Pin 2): Inverting Input of A Channel Amplifier.
+IN A (Pin 3): Noninverting Input of A Channel Amplifier.
V– (Pin 4): Negative Supply Voltage, Usually –5V.
+IN B (Pin 5): Noninverting Input of B Channel Amplifier.
–IN B (Pin 6): Inverting Input of B Channel Amplifier.
OUT B (Pin 7): B Channel Output.
NC (Pin 8): No Connection.
V+ (Pin 8): Positive Supply Voltage, Usually 5V.
NC (Pin 9): No Connection.
OUT C (Pin 10): C Channel Output.
LT1397CS
–IN C (Pin 11): Inverting Input of C Channel Amplifier.
+IN C (Pin 12):Noninverting Input of C Channel Amplifier.
V– (Pin 13): Negative Supply Voltage, Usually –5V.
+IND(Pin14):NoninvertingInputofDChannelAmplifier.
–IN D (Pin 15): Inverting Input of D Channel Amplifier.
OUT D (Pin 16): D Channel Output.
OUT A (Pin 1): A Channel Output.
–IN A (Pin 2): Inverting Input of A Channel Amplifier.
+IN A (Pin 3): Noninverting Input of A Channel Amplifier.
V+ (Pin 4): Positive Supply Voltage, Usually 5V.
+IN B (Pin 5): Noninverting Input of B Channel Amplifier.
–IN B (Pin 6): Inverting Input of B Channel Amplifier.
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PPLICATI
A
S I FOR ATIO
Feedback Resistor Selection
resistor, the closed-loop gain and the load resistor. The
LT1395/LT1396/LT1397 have been optimized for ±5V
supply operation and have a –3dB bandwidth of 400MHz
at a gain of 1 and 350MHz at a gain of 2. Please refer to the
resistor selection guide in the Typical AC Performance
table.
Thesmall-signalbandwidthoftheLT1395/LT1396/LT1397
is set by the external feedback resistors and the internal
junction capacitors. As a result, the bandwidth is a func-
tion of the supply voltage, the value of the feedback
7
LT1395/ LT1396/ LT1397
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PPLICATI
S I FOR ATIO
A
Capacitance on the Inverting Input
the feedback resistor and internal capacitance. At a gain
of 2 with 255Ω feedback and gain resistors and ±5V
supplies, theoutputslewrateis typically800V/µs. Larger
feedback resistors will reduce the slew rate as will lower
supply voltages.
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).
Differential Input Signal Swing
To avoid any breakdown condition on the input transis-
tors, thedifferentialinputswingmustbelimitedto±5V. In
normal operation, the differential voltage between the
input pins is small, so the ±5V limit is not an issue.
Capacitive Loads
The LT1395/LT1396/LT1397 can drive many capacitive
loads directly when the proper value of feedback resistor
is used. The required value for the feedback resistor will
increaseas loadcapacitanceincreases andas closed-loop
gaindecreases. Alternatively, asmallresistor(5Ωto35Ω)
canbeputinseries withtheoutputtoisolatethecapacitive
loadfromtheamplifieroutput. This has theadvantagethat
the amplifier bandwidth is only reduced when the capaci-
tive load is present. The disadvantage is that the gain is a
function of the load resistance. See the Typical Perfor-
mance Characteristics curves.
Buffered RGB to Color-Difference Matrix
An LT1397 can be used to create buffered color-differ-
ence signals from RGB inputs (Figure 1). In this applica-
tion, the R input arrives via 75Ω coax. It is routed to the
noninverting input of LT1397 amplifier A1 and to a 845Ω
resistor R8. There is also an 82.5Ω termination resistor
R11, which yields a 75Ω input impedance at the R input
when considered in parallel with R8. R8 connects to the
inverting input of a second LT1397 amplifier (A2), which
also sums the weighted G and B inputs to create a
–0.5 • Y output. LT1397 amplifier A3 then takes the
–0.5 • Y output and amplifies it by a gain of –2, resulting
in the Y output. Amplifier A1 is configured in a noninvert-
ing gain of 2 with the bottom of the gain resistor R2 tied
to the Y output. The output of amplifier A1 thus results in
the color-difference output R-Y.
Power Supplies
The LT1395/LT1396/LT1397 will operate from single or
split supplies from ±2V (4V total) to ±6V (12V total). It
is not necessary to use equal value split supplies, how-
ever the offset voltage and inverting input bias current
will change. The offset voltage changes about 2.5mV per
volt of supply mismatch. The inverting bias current will
typicallychangeabout10µApervoltofsupplymismatch.
The B input is similar to the R input. It arrives via 75Ω
coax, and is routed to the noninverting input of LT1397
amplifier A4, and to a 2320Ω resistor R10. There is also
a 76.8Ω termination resistor R13, which yields a 75Ω
input impedance when considered in parallel with R10.
R10 also connects to the inverting input of amplifier A2,
adding the B contribution to the Y signal as discussed
above. Amplifier A4 is configured in a noninverting gain
of 2 configuration with the bottom of the gain resistor R4
tied to the Y output. The output of amplifier A4 thus
results in the color-difference output B-Y.
Slew Rate
Unlike a traditional voltage feedback op amp, the slew rate
of a current feedback amplifier is not independent of the
amplifier gain configuration. In a current feedback ampli-
fier,boththeinputstageandtheoutputstagehaveslewrate
limitations.Intheinvertingmode,andforgains of2ormore
inthenoninvertingmode,thesignalamplitudebetweenthe
input pins is small and the overall slew rate is that of the
outputstage.Forgains less than2inthenoninvertingmode,
the overall slew rate is limited by the input stage.
The G input also arrives via 75Ω coax and adds its
contributiontotheYsignalviaa432ΩresistorR9, which
is tied to the inverting input of amplifier A2. There is also
a 90.9Ω termination resistor R12, which yields a 75Ω
The input slew rate of the LT1395/LT1396/LT1397 is
approximately600V/µs andis setbyinternalcurrents and
capacitances. The output slew rate is set by the value of
8
LT1395/ LT1396/ LT1397
O U
W
U
PPLICATI
A
S I FOR ATIO
termination when considered in parallel with R9. Using
superposition, it is straightforward to determine the
output of amplifier A2. Although inverted, it sums the R,
G and B signals in the standard proportions of 0.3R,
0.59G and 0.11B that are used to create the Y signal.
Amplifier A3 then inverts and amplifies the signal by 2,
resulting in the Y output.
is attenuated via resistors R6 and R7 such that amplifier
A2’s noninverting input sees 0.83Y. Using superposition,
we can calculate the positive gain of A2 by assuming that
R8 and R9 are grounded. This results in a gain of 2.41 and
a contribution at the output of A2 of 2Y. The R-Y input is
amplified by A2 with the gain set by resistors R8 and R10,
giving an amplification of –1.02. This results in a contri-
bution at the output of A2 of 1.02Y – 1.02R. The B-Y input
is amplified by A2 with the gain set by resistors R9 and
R10, giving an amplification of –0.37. This results in a
contribution at the output of A2 of 0.37Y – 0.37B.
+
75Ω
SOURCES
R8
845Ω
A1
R-Y
1/4 LT1397
R
–
R1
255Ω
R11
82.5Ω
R9
432Ω
R7
G
B
255Ω
R12
90.9Ω
Ifwenowsumthethreecontributions attheoutputofA2,
we get:
R10
2320Ω
–
R6
127Ω
R5
255Ω
R2
255Ω
R13
A2
76.8Ω
1/4 LT1397
A2OUT = 3.40Y – 1.02R – 0.37B
+
–
A3
It is important to remember though that Y is a weighted
sum of R, G and B such that:
Y
1/4 LT1397
+
R4
255Ω
Y = 0.3R + 0.59G + 0.11B
R3
255Ω
–
If we substitute for Y at the output of A2 we then get:
ALL RESISTORS 1%
= ±5V
A4
B-Y
V
S
1/4 LT1397
1395/6/7 F01
A2OUT = (1.02R – 1.02R) + 2G + (0.37B – 0.37B)
= 2G
+
Figure 1. Buffered RGB to Color-Difference Matrix
Theback-terminationresistorR11thenhalves theoutput
of A2 resulting in the G output.
Buffered Color-Difference to RGB Matrix
An LT1395 combined with an LT1396 can be used to
create buffered RGB outputs from color-difference sig-
nals (Figure 2). The R output is a back-terminated 75Ω
signal created using resistor R5 and amplifier A1 config-
ured for a gain of +2 via 255Ω resistors R3 and R4. The
noninverting input of amplifier A1 is connected via 1k
resistors R1 and R2 to the Y and R-Y inputs respectively,
resulting in cancellation of the Y signal at the amplifier
input. The remaining R signal is then amplified by A1.
R1
1k
Y
R2
1k
R5
75Ω
+
A1
R-Y
R
1/2 LT1396
–
R3
267Ω
R4
267Ω
R6
205Ω
R11
75Ω
+
R7
1k
A2
G
LT1395
–
R10
267Ω
R8
261Ω
The B output is also a back-terminated 75Ω signal
created using resistor R16 and amplifier A3 configured
for a gain of +2 via 255Ω resistors R14 and R15. The
noninverting input of amplifier A3 is connected via 1k
resistors R12 and R13 to the Y and B-Y inputs respec-
tively, resulting in cancellation of the Y signal at the
amplifier input. The remaining B signal is then amplified
by A3.
R9
698Ω
B-Y
R12
1k
R16
75Ω
+
A3
R13
1k
B
1/2 LT1396
–
R14
267Ω
ALL RESISTORS 1%
= ±5V
V
S
R15
267Ω
1395/6/7 F02
The G output is the most complicated of the three. It is a
weighted sum of the Y, R-Y and B-Y inputs. The Y input
Figure 2. Buffered Color-Difference to RGB Matrix
9
LT1395/ LT1396/ LT1397
W
W
, each amplifier
SI PLIFIED SCHE ATIC
+
V
–IN
OUT
+IN
–
V
1395/6/7 SS
U
Dimensions in inches (millimeters) unless otherwise noted.
PACKAGE DESCRIPTIO
GN Package
16-Lead Plastic SSOP (Narrow 0.150)
(LTC DWG # 05-08-1641)
0.189 – 0.196*
(4.801 – 4.978)
0.009
(0.229)
REF
16 15 14 13 12 11 10 9
0.229 – 0.244
(5.817 – 6.198)
0.150 – 0.157**
(3.810 – 3.988)
1
2
3
4
5
6
7
8
0.015 ± 0.004
(0.38 ± 0.10)
× 45°
0.053 – 0.068
(1.351 – 1.727)
0.004 – 0.0098
(0.102 – 0.249)
0.007 – 0.0098
(0.178 – 0.249)
0° – 8° TYP
0.016 – 0.050
(0.406 – 1.270)
0.0250
(0.635)
BSC
0.008 – 0.012
(0.203 – 0.305)
* 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
GN16 (SSOP) 1098
10
LT1395/ LT1396/ LT1397
U
Dimensions in inches (millimeters) unless otherwise noted.
PACKAGE DESCRIPTIO
MS8 Package
8-Lead Plastic MSOP
(LTC DWG # 05-08-1660)
0.118 ± 0.004*
(3.00 ± 0.102)
8
7
6
5
0.040 ± 0.006
(1.02 ± 0.15)
0.034 ± 0.004
(0.86 ± 0.102)
0.007
(0.18)
0° – 6° TYP
0.118 ± 0.004**
(3.00 ± 0.102)
SEATING
PLANE
0.193 ± 0.006
(4.90 ± 0.15)
0.012
(0.30)
REF
0.021 ± 0.006
(0.53 ± 0.015)
0.006 ± 0.004
(0.15 ± 0.102)
0.0256
(0.65)
BSC
MSOP (MS8) 1098
1
2
3
4
* DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH,
PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
S8 Package
8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.189 – 0.197*
(4.801 – 5.004)
0.010 – 0.020
(0.254 – 0.508)
7
5
8
6
× 45°
0.053 – 0.069
(1.346 – 1.752)
0.004 – 0.010
(0.101 – 0.254)
0.008 – 0.010
(0.203 – 0.254)
0°– 8° TYP
0.150 – 0.157**
(3.810 – 3.988)
0.228 – 0.244
(5.791 – 6.197)
0.016 – 0.050
(0.406 – 1.270)
0.050
(1.270)
BSC
0.014 – 0.019
(0.355 – 0.483)
TYP
*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
1
3
4
2
SO8 1298
S Package
14-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.337 – 0.344*
(8.560 – 8.738)
0.010 – 0.020
(0.254 – 0.508)
14
13
12
11
10
9
8
× 45°
0.053 – 0.069
(1.346 – 1.752)
0.004 – 0.010
(0.101 – 0.254)
0.008 – 0.010
(0.203 – 0.254)
0° – 8° TYP
0.228 – 0.244
0.150 – 0.157**
(5.791 – 6.197)
(3.810 – 3.988)
0.050
(1.270)
BSC
0.014 – 0.019
(0.355 – 0.483)
TYP
0.016 – 0.050
(0.406 – 1.270)
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
S14 1298
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
1
2
3
4
5
6
7
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 its circuits as described herein will not infringe onexisting patent rights.
11
LT1395/ LT1396/ LT1397
U
O
TYPICAL APPLICATI
Single Supply RGB Video Amplifier
input. Assuming a 75Ω source impedance for the signal
driving V , the Thevenin equivalent signal arriving at
IN
The LT1395 can be used with a single supply voltage of
6V or more to drive ground-referenced RGB video. In
Figure3,two1N4148diodes D1andD2havebeenplaced
in series with the output of the LT1395 amplifier A1 but
within the feedback loop formed by resistor R8. These
diodes effectively level-shift A1’s output downward by 2
diodes, allowing the circuit output to swing to ground.
A1’s positive input is 3V + 0.4V , with a source imped-
IN
ance of 714Ω. The combination of these two inputs gives
anoutputatthecathodeofD2of2•V withnoadditional
IN
DC offset. The 75Ω back termination resistor R9 halves
the signal again such that VOUT equals a buffered version
of V .
IN
It is important to note that the 4.7µF capacitor C1 has
been added to provide enough current to maintain the
voltage drop across diodes D1 and D2 when the circuit
outputdrops lowenoughthatthediodes mightotherwise
turn off. This means that this circuit works fine for
continuous videoinput, butwillrequirethatC1chargeup
after a period of inactivity at the input.
Amplifier A1 is used in a positive gain configuration. The
feedback resistor R8 is 255Ω. The gain resistor is cre-
ated from the parallel combination of R6 and R7, giving
a Thevenin equivalent 63.5Ω connected to 3.75V. This
gives an AC gain of +5 from the noninverting input of
amplifier A1 to the cathode of D2. However, the video
input is also attenuated before arriving at A1’s positive
5V
C1
4.7µF
V
S
R1
R6
6V TO 12V
1000Ω
84.5Ω
D1
D2
R9
75Ω
+
–
V
OUT
1N4148 1N4148
A1
LT1395
R2
1300Ω
R3
160Ω
R8
255Ω
V
IN
1395/6/7 TA03
R4
75Ω
R7
255Ω
R5
2.32Ω
Figure 3. Single Supply RGB Video Amplifier (1 of 4 Channels)
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LT1227/LT1229/LT1230
LT1252/LT1253/LT1254
LT1398/LT1399
140MHz Single/Dual/Quad Current Feedback Amplifier 1100V/µs Slew Rate, Single Adds Shutdown Pin
Low Cost Video Amplifiers
Single, Dual and Quad 100MHz Current Feedback Amplifiers
300MHz Bandwidth, 0.1dB Flatness > 150MHz with Shutdown
2.5ns Switching Time, 250MHz Bandwidth
Dual/Triple Current Feedback Amplifiers
Triple 2:1 Buffered Video Mulitplexer
70MHz Single/Dual/Quad Op Amps
LT1675
LT1363/LT1364/LT1365
1000V/µs Slew Rate, Voltage Feedback
139567f LT/TP 0100 4K • PRINTED IN USA
LINEAR TECHNOLOGY CORPORATION 1999
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
12
●
●
(408)432-1900 FAX:(408)434-0507 www.linear-tech.com
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