Analog Devices Inc. 的 LT1223 规格书

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LT1223
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TYPICAL APPLICATIO
U
APPLICATIO S
U
DESCRIPTIO
U
FEATURES
100MHz Current
Feedback Amplifier
■
100MHz Bandwidth at A
V
= 1
■
1000V/µs Slew Rate
■
Wide Supply Range: ±5V to ±15V
■
1mV Input Offset Voltage
■
1µA Input Bias Current
■
5MΩ Input Resistance
■
75ns Settling Time to 0.1%
■
50mA Output Current
■
6mA Quiescent Current
■
Available in 8-Lead Plastic DIP and SO Packages
■
Video Amplifiers
■
Buffers
■
IF and RF Amplification
■
Cable Drivers
■
8-, 10-, 12-Bit Data Acquisition Systems
The LT
®
1223 is a 100MHz current feedback amplifier with
very good DC characteristics. The LT1223’s high slew
rate, 1000V/µs, wide supply range, ±15V, and large output
drive, ±50mA, make it ideal for driving analog signals over
double-terminated cables. The current feedback amplifier
has high gain bandwidth at high gains, unlike conventional
op amps.
The LT1223 comes in the industry standard pinout and
can upgrade the performance of many older products.
The LT1223 is manufactured on Linear Technology’s
proprietary complementary bipolar process.
Video Cable Driver Voltage Gain vs Frequency
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Ω
IN
V
OUT
V
R
G
1k
R
F
1k
75
75
CABLE
Ω
75Ω
+
–
LT1223
LT1223 • TA02
A = 1 +
V
R
F
R
G
AT AMPLIFIER OUTPUT
6dB LESS AT V
OUT
FREQUENCY (Hz)
100k
–20
VOLTAGE GAIN (dB)
–10
10
20
50
60
10M 100M 1G
LT1223 • TPC01
1M
0
30
40
100MHz GAIN
BANDWIDTH
R
G
= 10
R
G
= 33
R
G
= 110
R
G
= 470
R
G
= ∞
1k
R
G
+
–
:1 V Differential Input Voltage ............................. 15V E % Input Voltage .. Equal to Supply Voltage E :1 Output Short Circuit Duration (Note 2) ......... Continuous E 3 Operating Temperature Range LT1223M (OBSOLETE) —55°C to 125°C LT12230 ........................ 0°C to 70“C Emiggig :1::1;‘;”031W Storage Temperature Range 765% to 150“C Junction Temperature Plastic Package ........... 150“C B,Lgfi%2‘}%“fnfiinip Junction Temperature Ceramic Package Timwwswteiwmw OBSDL (OBSOLETE) Lead Temperature (Soldering, 10 sec.) Consider the M Consult LTD Marketing lor parts so /\‘ /\‘ 2 L7HHWEQB
LT1223
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ORDER PART
NUMBER
ABSOLUTE AXI U RATI GS
W
WW
U
(Note 1)
J8 PACKAGE
8-LEAD CERAMIC DIP
TJMAX = 175°C, θJA = 100°CW (J8)
WU
U
PACKAGE/ORDER I FOR ATIO
S8 PART MARKING
LT1223CN8
LT1223CS8
1223
T
J MAX
= 150°C, θ
JA
= 100°C/W(N8)
T
J MAX
= 150°C, θ
JA
= 150°C/W(S8)
OBSOLETE PACKAGE
Consider the N8 or S8 for Alternative Source
Supply Voltage ...................................................... ±18V
Differential Input Voltage ......................................... ±5V
Input Voltage ............................ Equal to Supply Voltage
Output Short Circuit Duration (Note 2) .........Continuous
Operating Temperature Range
LT1223M (OBSOLETE) .............. –55°C to 125°C
LT1223C................................................ 0°C to 70°C
Storage Temperature Range ..................–65°C to 150°C
Junction Temperature Plastic Package ........... 150°C
Junction Temperature Ceramic Package
(OBSOLETE) ..................................... 175°C
Lead Temperature (Soldering, 10 sec.)................. 300°C
LT1223CJ8
LT1223MJ8
Consult LTC Marketing for parts specified with wider operating temperature ranges.
1
2
3
4
8
7
6
5
TOP VIEW
NULL
–IN
+IN
V
–
SHUTDOWN
V
+
OUT
NULL
N8 PACKAGE
8-LEAD PLASTIC DIP
S8 PACKAGE
8-LEAD PLASTIC SO
ELECTRICAL CHARACTERISTICS
LT1223M/C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
OS
Input Offset Voltage V
CM
= 0V ±1±3mV
I
IN
+ Noninverting Input Current V
CM
= 0V ±1±3µA
I
IN
– Inverting Input Current V
CM
= 0V ±1±3µA
e
n
Input Noise Voltage Density f = 1kHz, R
F
= 1k, R
G
= 10Ω3.3 nV/√Hz
i
n
Input Noise Current Density f = 1kHz, R
F
= 1k, R
G
= 10Ω2.2 pA/√Hz
R
IN
Input Resistance V
IN
= ±10V 1 10 MΩ
C
IN
Input Capacitance 1.5 pF
Input Voltage Range ±10 ±12 V
CMRR Common Mode Rejection Ratio V
CM
= ±10V 56 63 dB
Inverting Input Current Common Mode Rejection V
CM
= ±10V 30 100 nA/V
PSRR Power Supply Rejection Ratio V
S
= ±4.5V to ±18V 68 80 dB
Noninverting Input Current Power Supply Rejection V
S
= ±4.5V to ±18V 12 100 nA/V
Inverting Input Current Power Supply Rejection V
S
= ±4.5V to ±18V 60 500 nA/V
A
V
Large Signal Voltage Gain R
LOAD
= 400Ω, V
OUT
= ±10V 70 89 dB
R
OL
Transresistance, ∆V
OUT
/∆I
IN
–R
LOAD
= 400Ω, V
OUT
= ±10V 1.5 5 MΩ
V
OUT
Maximum Output Voltage Swing R
LOAD
= 200Ω±10 ±12 V
I
OUT
Maximum Output Current R
LOAD
= 200Ω50 60 mA
SR Slew Rate R
F
= 1.5k, R
G
= 1.5k (Note 3) 800 1300 V/µs
BW Bandwidth R
F
= 1k, R
G
= 1k, V
OUT
= 100mV 100 MHz
V
S
= ±15V, T
A
= 25°C, unless otherwise noted.
Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
LT1223
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ELECTRICAL CHARACTERISTICS
LT1223M/C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
t
r
Rise Time R
F
= 1.5k, R
G
= 1.5k, V
OUT
= 1V 6.0 ns
t
PD
Propagation Delay R
F
= 1.5k, R
G
= 1.5k, V
OUT
= 1V 6.0 ns
Overshoot R
F
= 1.5k, R
G
= 1.5k, V
OUT
= 1V 5 %
t
s
Settling Time, 0.1% R
F
= 1k, R
G
= 1k, V
OUT
= 10V 75 ns
Differential Gain R
F
= 1k, R
G
= 1k, R
L
= 150Ω0.02 %
Differential Phase R
F
= 1k, R
G
= 1k, R
L
= 150Ω0.12 Deg
R
OUT
Open-Loop Output Resistance V
OUT
= 0, I
OUT
= 0 35 Ω
I
S
Supply Current V
IN
= 0V 6 10 mA
Supply Current, Shutdown Pin 8 Current = 200µA24mA
VS = ±15V, TA = 25°C, unless otherwise noted.
LT1223C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
OS
Input Offset Voltage V
CM
= 0V ●±1±3mV
I
IN
+ Noninverting Input Current V
CM
= 0V ●±1±3µA
I
IN
– Inverting Input Current V
CM
= 0V ●±1±3µA
R
IN
Input Resistance V
IN
= ±10V ●110 MΩ
Input Voltage Range ●±10 ±12 V
CMRR Common Mode Rejection Ratio V
CM
= ±10V ●56 63 dB
Inverting Input Current Common Mode Rejection V
CM
= ±10V ●30 100 nA/V
PSRR Power Supply Rejection Ratio V
S
= ±4.5V to ±18V ●68 80 dB
Noninverting Input Current Power Supply Rejection V
S
= ±4.5V to ±18V ●12 100 nA/V
Inverting Input Current Power Supply Rejection V
S
= ±4.5V to ±18V ●60 500 nA/ V
A
V
Large-Signal Voltage Gain R
LOAD
= 400Ω, V
OUT
= ±10V ●70 89 dB
R
OL
Transresistance, ∆V
OUT
/∆I
IN
–R
LOAD
= 400Ω, V
OUT
= ±10V ●1.5 5 MΩ
V
OUT
Maximum Output Voltage Swing R
LOAD
= 200Ω●±10 ±12 V
I
OUT
Maximum Output Current R
LOAD
= 200Ω●50 60 mA
I
S
Supply Current V
IN
= 0V ●610 mA
Supply Current, Shutdown Pin 8 Current = 200µA●24 mA
The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at VS = ±15V,
VCM = 0V, 0°C ≤ TA ≤ 70°C, unless otherwise noted.
L7LJlJWEI§E
LT1223
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LT1223M
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
OS
Input Offset Voltage V
CM
= 0V ●±1±5mV
I
IN+
Noninverting Input Current V
CM
= 0V ●±1±5µA
I
IN–
Inverting Input Current V
CM
= 0V ●±1±10 µA
R
IN
Input Resistance V
IN
= ±10V ●110 MΩ
Input Voltage Range ●±10 ±12 V
CMRR Common Mode Rejection Ratio V
CM
= ±10V ●56 63 dB
Inverting Input Current Common Mode Rejection V
CM
= ±10V ●30 100 nA/V
PSRR Power Supply Rejection Ratio V
S
= ±4.5V to ±15V ●68 80 dB
Noninverting Input Current Power Supply Rejection V
S
= ±4.5V to ±15V ●12 200 nA/V
Inverting Input Current Power Supply Rejection V
S
= ±4.5V to ±15V ●60 500 nA/V
A
V
Large-Signal Voltage Gain R
LOAD
= 400Ω, V
OUT
= ±10V ●70 89 dB
R
OL
Transresistance, ∆V
OUT
/∆I
IN
–R
LOAD
= 400Ω, V
OUT
= ±10V ●1.5 5 MΩ
V
OUT
Maximum Output Voltage Swing R
LOAD
= 200Ω●±7±12 V
I
OUT
Maximum Output Current R
LOAD
= 200Ω●35 60 mA
I
S
Supply Current V
IN
= 0V ●610 mA
Supply Current, Shutdown Pin 8 Current = 200µA●24 mA
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: A heat sink may be required.
Note 3: Noninverting operation, V
OUT
= ±10V, measured at ±5V.
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at VS = ±15V, VCM = 0V, –55°C ≤ TA ≤ 125°C, unless otherwise noted.
l0 8 / 3 25°C __ ----—” a? g ‘25 C/// j 7 c U 4 55 / z 2 y u g D 2 4 5 E l0 l2 l4 l5 VB 2L7 sumv VOLTAGE (:Vl Input Common Mode Limilvs Temperature ”e vs Common Mode Voltage vymv E S as A w <5 e="" 3="" e="" _="" e="" g="" g="" c:="" d="" v5="15v" \r="" ’50="" ’25="" u="" 25="" 5d="" 75="" h70="" ‘25="" 45="" 4u="" *5="" [i="" 5="" w="" l5="" temperature="" (cc;="" ’="" common="" mdde="" voltage="" (v)’="" _="" output="" voltage="" swing="" vs="" output="" voltage="" swing="" vs="" v05="" vs="" common="" mode="" voltage="" load="" resistor="" supply="" voltage="" 0="" vs="tl5V" vnslmvl="" 45="" 7w="" 75="" o="" 5="" to="" l5="" common="" mdde="" voltage="" (vi="" 122%="" l7tjuwe'zse="" 5="">
LT1223
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TYPICAL PERFOR A CE CHARACTERISTICS
UW
Supply Current vs Supply Voltage, Supply Current vs Supply Voltage Output Short Circuit-Current vs
VIN = 0 (Operating) (Shutdown) Temperature
Input Common Mode Limit vs
Temperature +IB vs Common Mode Voltage –IB vs Common Mode Voltage
Output Voltage Swing vs Output Voltage Swing vs
VOS vs Common Mode Voltage Load Resistor Supply Voltage
SUPPLY VOLTAGE (±V)
0
0
SUPPLY CURRENT (mA)
2
4
6
8
10
LT1223 • TPC02
2 4 6 8 101214161820
–55°C
25°C
125°C
SUPPLY VOLTAGE (±V)
0
0
SUPPLY CURRENT (mA)
1
2
3
4
LT1223 • TPC03
2 4 6 8 101214161820
125°C
–55°C
PIN 8 = 0V
25°C
CASE TEMPERATURE (°C)
–50
0
OUTPUT SHORT CIRCUIT CURRENT (mA)
30
100
LT1223 • TPC04
–25 0 25 50 75 100 125
10
20
40
50
60
70
80
90
TEMPERATURE (°C)
COMMON MODE RANGE (V)
2
LT1223 • TPC05
1
3
4
–4
–3
–2
–1
V = ±15V
S
V = ±5V
S
V = 15V
S
V = 5V
S
–50 –25 0 25 50 75 100 125
V+
V–
COMMON MODE VOLTAGE (V)
–15
–5
I
B
(µA)
–3
–1
1
3
5
LT1223 • TPC06
–10 –5 0 5 10 15
25°C
125°C
–4
–2
0
2
4
–55°C
V = ±15V
S
COMMON MODE VOLTAGE (V)
–15
–10
–IB (µA)
–6
–2
2
6
10
LT1223 ∑ TPC07
–10 –5 0 5 10 15
125°C
–8
–4
0
4
8
–55°C
±V = 15V
S
25°C
COMMON MODE VOLTAGE (V)
–15
–20
V (mV)
–10
10
20
LT1223 • TPC08
–10 –5 0 5 10 15
–15
–5
0
5
15
–55°C
25°C
125°C
OS
V = 15V
S
±
LOAD RESISTOR ( )
100
–20
OUTPUT VOLTAGE SWING (V)
15
20
1000 10000
LT1223 • TPC09
Ω
–15
–10
–5
0
5
10
125°C
V
S
= ±15V
25°C, –55°C
125°C
25°C, –55°C
SUPPLY VOLTAGE (±V)
0
–20
OUTPUT VOLTAGE SWING (V)
–10
–5
10
20
LT1223 • TPC10
2 4 6 8 101214161820
125°C
–15
0
5
15
25°C
25°C
125°C
–55°C
–55°C
iuu 43:18 BANDWIDTH (MHZ) i 2 3 FEEDEACK RESiSTOR (m) Maximum Capacitive Load vs Open-Loop Voltaqe Gain vs Feeilhack Resistor Load Resistor iflk WU AV = 21;: R5 2510 Mann Vs = :isv PEAKWG<5¢b a="" so="" 3="" ik="" 5="" 80="" e="" a="" 9="" s="" e="" a="" 70="" e="" i="" e="" ion="" g="" so="" 3="" 50="" ll)="" 40="" u="" l="" 2="" 3="" ieiei="" ieieiei="" ieieieiei="" feedback="" resistur="" (my="" load="" “mm="" (m="" spot="" noise="" vollage="" and="" current="" vs="" power="" supply="" reieclion="" vs="" frequency="" frequency="" dulput="" impedance="" vs="" frequency="" iuuu="" 3“="" v5=":iiv" r;="W" t:="" g="" positive="" %_="" s="" 60="" g="" “10="" e="" lin="" a="" ;="" g="" nega‘hve="" a="" in="" a="" z="" e="" e="" 3="" 2“="" $="" t:="" in="" ion="" ik="" ink="" frequencv="" (hz)="" 12234::="" 6="" l7lil1wei§b="">
LT1223
6
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TYPICAL PERFOR A CE CHARACTERISTICS
UW
–3dB Bandwidth vs –3dB Bandwidth vs Minimum Feedback Resistor vs
Feedback Resistor Supply Voltage Voltage Gain
Maximum Capacitive Load vs Open-Loop Voltage Gain vs
Feedback Resistor Load Resistor Transimpedance vs Load Resistor
Spot Noise Voltage and Current vs Power Supply Rejection vs
Frequency Frequency Output Impedance vs Frequency
FEEDBACK RESISTOR (k )
0
0
–3dB BANDWIDTH (MHz)
30
100
LT1223 • TPC11
123
10
20
40
50
60
70
80
90
Ω
LS
Ω
A = 2; RF = RG
R = 100 ; V = 15V
NO CAPACITIVE LOAD
V±
SUPPLY VOLTAGE ( V)
0
0
–3dB BANDWIDTH (MHz)
30
100
LT1223 • TPC12
51015
10
20
40
50
60
70
80
90
±
R
F
= 750 R
F
= 1k
R
F
= 1.5k
R
F
= 2k
R
F
= R
G
A = 2
R = 100
T = 25°C
V
Ω
A
L
VOLTAGE GAIN (V/V)
0
100
FEEDBACK RESISTOR ( )
400
1000
LT1223 • TPC13
20 40 60
200
300
500
600
700
800
900
10 30 50
Ω
2dB PEAKING
0dB PEAKING
V = 15V
R = 100
S±
L
FEEDBACK RESISTOR (k )
0
10
CAPACITIVE LOAD (pF)
100
1k
10k
123
LT1223 • TPC14
Ω
LS
A = 2; R
F
= R
G
R = 100; V = 15V
PEAKING < 5dB
V
±
LOAD RESISTOR ( )
100
40
OPEN LOOP VOLTAGE GAIN (dB)
100
1000 10000
LT1223 • TPC15
Ω
50
60
70
80
90
–55°C
25°C
125°C
V = 15V
V = 10V
S
±
O
±
LOAD RESISTOR ( )
100
0
TRANSIMPEDANCE (M )
10
1000 10000
LT1223 • TPC16
Ω
1
2
3
5
Ω
4
6
7
8
9V = 15V
V = 10V
S
±
O
±
–55°C
25°C
125°C
FREQUENCY (Hz)
10
1
SPOT NOISE (nV/ OR pA/ )
10
100
1000
100 1k 10k
LT1223 • TPC17
en
+in
–in
Hz Hz√√
FREQUENCY (Hz)
20
POWER SUPPLY REJECTION (dB)
40
60
80
10k 1M 10M 100M
LT1223 • TPC18
0
100k
NEGATIVE
POSITIVE
V = ±15V
R
F
= 1k
S
FREQUENCY (Hz)
0.1
MAGNITUDE OF OUTPUT IMPEDANCE ( )
1
10
100
10k 1M 10M 100M
LT1223 • TPC19
0.01
100k
Ω
R
F
= R
G
= 3k
V = 15V
S
±
R
F
= R
G
= 1k
225 v5: :ISV R; = R5 : lk ‘30 l35 1: E Rflflflfl in; tk 9” E E 45 g :3 PHASE i 5 in 2 t a e E Rl : ions: ’45 g E 790 a 435' 430 *225 IM iuM work is Ink max FREQUENCV (Hz) . . CV(H1) . . Nuninvertinp Amplilier Settling Nnninvertinp Amplilier Settling Inverting Amplifier Settling Timetu1l1mV vs Output Step Timetu1mV vs Output Step Time vs Output Step Av=ol szti Rp=lk i2;=ii< umv="" v5="1t5V" vs="tt5V" anix="" rl="lk" o="" 20="" no="" so="" on="" ion="" settling="" tlme="" [its]="" flpplicf-itioi'is="" inronmnrion="" current="" feedback="" basics="" the="" small»signal="" bandwidth="" otthe="" lt1223,="" like="" all="" current="" does="" in="" a="" voltage="" feedback="" amplifiers,="" isn'tastraight="" inverse="" function="" ofthe="" bandwidth="" does="" n="" closed»loop="" gain.="" this="" is="" because="" the="" feedback="" resistors="" lent="" gain="" bandwidt="" determine="" the="" amount="" of="" current="" driving="" the="" amplifier’s="" plitier="" is="" set="" by="" the="" internal="" compensation="" capacitor.="" in="" fact,="" the="" amplifier’s="" inverting="" input="" and="" feedback="" resistor="" (r;)="" from="" output="" to="" inverting="" input="" bykeeping="" rgcons="" works="" with="" internaljunction="" capacitancesofthe="" lt1223to="" thevenin="" resistanc="" set="" the="" closed»loop="" bandwidth.="" change="" in="" gain.="" as="" of="" the="" lt1223="" rem="" eventhoughthegainsetresistor(relfrominvertinginput="" gains="" to="" ground="" works="" with="" rf="" to="" set="" the="" voltage="" gain="" just="" like="" it="" l7jen2="">
LT1223
7
1223fb
APPLICATIO S I FOR ATIO
WUUU
TYPICAL PERFOR A CE CHARACTERISTICS
UW
does in a voltage feedback op amp, the closed-loop
bandwidth does not change. This is because the equiva-
lent gain bandwidth product of the current feedback am-
plifier is set by the Thevenin equivalent resistance at the
inverting input and the internal compensation capacitor.
By keeping R
F
constant and changing the gain with R
G
, the
Thevenin resistance changes by the same amount as the
change in gain. As a result, the net closed-loop bandwidth
of the LT1223 remains the same for various closed-loop
gains.
Voltage Gain and Phase vs Total Harmonic Distortion vs 2nd and 3rd Harmonic
Frequency Frequency Distortion vs Frequency
Noninverting Amplifier Settling Noninverting Amplifier Settling Inverting Amplifier Settling
Time to 10mV vs Output Step Time to 1mV vs Output Step Time vs Output Step
Current Feedback Basics
The small-signal bandwidth of the LT1223, like all current
feedback amplifiers, isn’t a straight inverse function of the
closed-loop gain. This is because the feedback resistors
determine the amount of current driving the amplifier’s
internal compensation capacitor. In fact, the amplifier’s
feedback resistor (R
F
) from output to inverting input
works with internal junction capacitances of the LT1223 to
set the closed-loop bandwidth.
Even though the gain set resistor (R
G
) from inverting input
to ground works with R
F
to set the voltage gain just like it
FREQUENCY (Hz)
1M
–30
VOLTAGE GAIN (dB)
–15
5
20
10M 100M 1G
LT1223 • TPC20
R 1k
L
GAIN
–25
–20
–10
–5
0
10
15
PHASE SHIFT (DEGREES)
–225
–90
90
225
–180
–135
–45
0
45
135
180
PHASE
≥
R = 100
LΩ
R 1k
L≥
R = 100
LΩ
V = 15V
RF = RG = 1k
S±
FREQUENCY (Hz)
TOTAL HARMONIC DISTORTION (%)
0.01
0.1
10 1k 10k 100k
LT1223 • TPC21
0.001
100
THD
V = 15V
V = 7V
R = 400
RF = RG =1k
S
O
L
±
RMS
Ω
FREQUENCY (MHz)
1
–70
DISTORTION (dBc)
–20
10 100
LT1223 • TPC22
–60
–50
–40
–30
2ND
3RD
V = 15V
V = 2V
P-P
R = 100
R
F
= 1k
A = 10dB
S
±
O
L
V
SETTLING TIME (ns)
0
–10
OUTPUT STEP (V)
–4
10
LT1223 • TPC23
20 40 60 80 100
–8
–6
–2
0
2
4
6
8
TO 10mV
TO 10mV
V
S
L
±
A = +1
R
F
= 1k
V = 15V
R = 1k
SETTLING TIME ( s)
0
–10
OUTPUT STEP (V)
–4
10
LT1223 • TPC24
12
–8
–6
–2
0
2
4
6
8
TO 1mV
µ
TO 1mV
A = +1
R = 1k
V = 15V
R = 1k
F
S±
V
L
SETTLING TIME (ns)
0
–10
OUTPUT STEP (V)
–4
10
LT1223 • TPC25
100
–8
–6
–2
0
2
4
6
8
TO 1mV
TO 10mV
A = –1
R = 1k
V = 15V
R = 1k
F
S
±
V
20 40 60 80
L
TO 10mV
TO 1mV
L7LJlJWEI§E
LT1223
8
1223fb
APPLICATIO S I FOR ATIO
WUUU
The curve on the first page shows the LT1223 voltage gain
versus frequency while driving 100Ω, for five gain settings
from 1 to 100. The feedback resistor is a constant 1k and
the gain resistor is varied from infinity to 10Ω. Shown for
comparison is a plot of the fixed 100MHz gain bandwidth
limitation that a voltage feedback amplifier would have. It
is obvious that for gains greater than one, the LT1223
provides 3 to 20 times more bandwidth. It is also evident
that second order effects reduce the bandwidth somewhat
at the higher gain settings.
Feedback Resistor Selection
Because the feedback resistor determines the compensa-
tion of the LT1223, bandwidth and transient response can
be optimized for almost every application. To increase the
bandwidth when using higher gains, the feedback resistor
(and gain resistor) can be reduced from the nominal 1k
value. The Minimum Feedback Resistor versus Voltage
Gain curve shows the values to use for ±15V supplies.
Larger feedback resistors can also be used to slow down
the LT1223 as shown in the –3dB Bandwidth versus
Feedback Resistor curve.
Capacitive Loads
The LT1223 can be isolated from capacitive loads with a
small resistor (10Ω to 20Ω) or it can drive the capacitive
load directly if the feedback resistor is increased. Both
techniques lower the amplifier’s bandwidth about the
same amount. The advantage of resistive isolation is that
the bandwidth is only reduced when the capacitive load is
present. The disadvantage of resistor isolation is that
resistive loading causes gain errors. Because the DC
accuracy is not degraded with resistive loading, the de-
sired way of driving capacitive loads, such as flash con-
verters, is to increase the feedback resistor. The Maximum
Capacitive Load versus Feedback Resistor curve shows
the value of feedback resistor and capacitive load that
gives 5dB of peaking. For less peaking, use a larger
feedback resistor.
Power Supplies
The LT1223 may be operated with single or split supplies
as low as ±4V (8V total) to as high as ±18V (36V total). It
is not necessary to use equal value split supplies, how-
ever, the offset voltage will degrade about 350µV per volt
of mismatch. The internal compensation capacitor de-
creases with increasing supply voltage. The –3dB Band-
width versus Supply Voltage curve shows how this affects
the bandwidth for various feedback resistors. Generally,
the bandwidth at ±5V supplies is about half the value it is
at ±15V supplies for a given feedback resistor.
The LT1223 is very stable even with minimal supply
bypassing, however, the transient response will suffer if
the supply rings. It is recommended for good slew rate and
settling time that 4.7µF tantalum capacitors be placed
within 0.5 inches of the supply pins.
Input Range
The noninverting input of the LT1223 looks like a 10M
resistor in parallel with a 3pF capacitor until the common
mode range is exceeded. The input impedance drops
somewhat and the input current rises to about 10µA when
the input comes too close to the supplies. Eventually,
when the input exceeds the supply by one diode drop, the
base collector junction of the input transistor forward
biases and the input current rises dramatically. The input
current should be limited to 10mA when exceeding the
supplies. The amplifier will recover quickly when the input
is returned to its normal common mode range unless the
input was over 500mV beyond the supplies, then it will
take an extra 100ns.
Offset Adjust
Output offset voltage is equal to the input offset voltage
times the gain plus the inverting input bias current times
the feedback resistor. For low gain applications (3 or less)
a 10kΩ pot connected to Pins 1 and 5 with wiper to V
+
will
trim the inverting input current (±10µA) to null the output;
it does not change the offset voltage very much. If the
LT1223 is used in a high gain application, where input
offset voltage is the dominate error, it can be nulled by
pulling approximately 100µA from Pin 1 or 5. The easy
way to do this is to use a 10kΩ pot between Pin 1 and 5 with
a 150k resistor from the wiper to ground for 15V supply
applications. Use a 47k resistor when operating on a 5V
supply.
LT1223
9
1223fb
Shutdown
Pin 8 activates a shutdown control function. Pulling more
than 200mA from Pin 8 drops the supply current to less
than 3mA, and puts the output into a high impedance state.
The easy way to force shutdown is to ground Pin 8, using
an open collector (drain) logic stage. An internal resistor
limits current, allowing direct interfacing with no addi-
tional parts. When Pin 8 is open, the LT1223 operates
normally.
Slew Rate
The slew rate of a current feedback amplifier is not inde-
pendent of the amplifier gain configuration the way it is in
a traditional op amp. This is because the input stage and
the output stage both have slew rate limitations. Inverting
amplifiers do not slew the input and are therefore limited
only by the output stage. High gain, noninverting amplifi-
ers are similar. The input stage slew rate of the LT1223 is
about 350V/µs before it becomes nonlinear and is en-
hanced by the normally reverse-biased emitters on the
input transistors. The output slew rate depends on the size
of the feedback resistors. The peak output slew rate is
about 2000V/µs with a 1k feedback resistor and drops
proportionally for larger values. At an output slew rate of
1000V/µs or more, the transistors in the “mirror circuits”
will begin to saturate due to the large feedback currents.
This causes the output to have slew induced overshoot and
is somewhat unusual looking; it is in no way harmful or
dangerous to the device. The photos show the LT1223 in
a noninverting gain of three (R
F
= 1k, R
G
= 500Ω) with a
20V peak-to-peak output slewing at 500V/µs, 1000V/µs
and 2000V/µs.
Settling Time
The Inverting Amplifier Settling Time versus Output Step
curve shows that the LT1223 will settle to within 1mV of
final value in less than 100ns for all output changes of 10V
or less. When operated as an inverting amplifier there is
less than 500µV of thermal settling in the amplifier.
However, when operating the LT1223 as a noninverting
amplifier, there is an additional thermal settling compo-
nent that is about 200µV for every volt of input common
mode change. So a noninverting gain of one amplifier will
Output Slew Rate at 2000V/µs Shows Aberrations (See Text)
Output Slew Rate of 1000V/µs
Output Slew Rate of 500V/µs
1223 A01
1223 A02
1223 A03
APPLICATIO S I FOR ATIO
WUUU
L7LJlJWEI§E
LT1223
10
1223fb
have about 2.5mV thermal tail on a 10V step. Unfortu-
nately, reducing the input signal and increasing the gain
always results in a thermal tail of about the same amount
for a given output step. For this reason we show separate
graphs of 10mV and 1mV non-inverting amplifier settling
times. Just as the bandwidth of the LT1223 is fairly
constant for various closed-loop gains, the settling time
remains constant as well.
Adjustable Gain Amplifier
To make a variable gain amplifier with the LT1223, vary the
value of R
G
. The implementation of R
G
can be a pot, a light
controlled resistor, a FET, or any other low capacitance
variable resistor. The value of R
F
should not be varied to
change the gain. If R
F
is changed, then the bandwidth will
be reduced at maximum gain and the circuit will oscillate
when R
F
is very small.
Adjustable Bandwidth Amplifier
Because the resistance at the inverting input determines
the bandwidth of the LT1223, an adjustable bandwidth
circuit can be made easily. The gain is set as before with
R
F
and R
G
; the bandwidth is maximum when the variable
resistor is at a minimum.
Accurate Bandwidth Limiting the LT1223
It is very common to limit the bandwidth of an op amp by
putting a small capacitor in parallel with R
F
. DO NOT PUT
A SMALL CAPACITOR FROM THE INVERTING INPUT OF
A CURRENT FEEDBACK AMPLIFIER TO ANYWHERE ELSE,
ESPECIALLY NOT TO THE OUTPUT. The capacitor on the
inverting input will cause peaking or oscillations. If you
need to limit the bandwidth of a current feedback amplifier,
use a resistor and capacitor at the noninverting input (R1
and C1). This technique will also cancel (to a degree) the
peaking caused by stray capacitance at the inverting input.
Unfortunately, this will not limit the output noise the way
it does for the op amp.
Current Feedback Amplifier Integrator
Since we remember that the inverting input wants to see
a resistor, we can add one to the standard integrator
circuit. This generates a new summing node where we can
apply capacitive feedback. The LT1223 integrator has
excellent large signal capability and accurate phase shift at
high frequencies.
APPLICATIO S I FOR ATIO
WUUU
LT1223 • TA03
+
–
IN
V
OUT
V
LT1223
R
F
R
G
LT1223 • TA04
+
–
IN
V
OUT
V
LT1223
R
F
5k
R
G
LT1223 • TA05
+
–
IN
V
OUT
V
LT1223
R
F
R
G
R1
R1 = 300
C1
Ω
C1 = 100pF
BW = 5MHz
LT1223 • TA06
+
–
IN
V
OUT
V
LT1223
R
F
1k C1
OUT
V
IN
V
1
sC1R1
=
R1
L7 JIJW #
LT1223
11
1223fb
inverting input (A1) senses the shield and the non-invert-
ing input (A2) senses the center conductor. Since this
amplifier does not load the cable (take care to minimize
stray capacitance) and it rejects common mode hum and
noise, several amplifiers can sense the signal with only
one termination at the end of the cable. The design
equations are simple. Just select the gain you need (it
should be two or more) and the value of the feedback
resistor (typically 1k) and calculate R
G1
and R
G2
. The gain
can be tweaked with R
G2
and the CMRR with R
G1
if needed.
The bandwidth of the noninverting input signal is not
reduced by the presence of the other amplifier, however,
the inverting input signal bandwidth is reduced since it
passes two amplifiers. The CMRR is good at high frequen-
cies because the bandwidth of the amplifiers are about the
same even though they do not necessarily operate at the
same gain.
Summing Amplifier (DC Accurate)
The summing amplifier is easily made by adding additional
inputs to the basic inverting amplifier configuration. The
LT1223 has no I
OS
spec because there is no correlation
between the two input bias currents. Therefore, we will not
improve the DC accuracy of the inverting amplifier by
putting in the extra resistor in the noninverting input.
Difference Amplifier
The LT1223 difference amplifier delivers excellent
performance if the source impedance is very low. This is
because the common mode input resistance is only equal
to R
F
+ R
G
.
Video Instrumentation Amplifier
This instrumentation amplifier uses two LT1223s to in-
crease the input resistance to well over 1M. This makes an
excellent “loop through” or cable sensing amplifier if the
Cable Driver
The cable driver circuit is shown on the front page. When
driving a cable it is important to properly terminate both
ends if even modest high frequency performance is
required. The additional advantage of this is that it isolates
the capacitive load of the cable from the amplifier so it can
operate at maximum bandwidth.
APPLICATIO S I FOR ATIO
WUUU
V = –R
LT1223 • TA07
+
–
In
V
OUT
V
LT1223
+
I1
V
I2
V
1
R
2
R
n
R
V V V
I1 I2 In
G1 G2 Gn
OUT F
•
•
•
R R R
+
G
G
G
RF
()
(R
F
– 50)
LT1223 • TA08
+
–
OUT
V
LT1223
R
F
100
V1
V2
OPTIONAL TRIM
FOR CMRR
R
G
R
G
(V1 – V2)
R
F
R
G
V
OUT
=
R
G1
1k
LT1223 • TA09
OUT
V
A1
LT1223
IN
V
A2
LT1223
IN
V
–+
++
––
R
F1
1k
R
G2
1k
R
F2
1k
V
OUT
= G (V
IN+
– V
IN–
)
R
F1
= R
F2
; R
G1
= (G – 1) R
F2
; R
G2
=
TRIM GAIN (G) WITH R
G2
; TRIM CMRR WITH R
G1
R
F2
G – 1
52:... (kl: 3JL [2 Wk KM 31 IE Wk k 21 2|. HE Ales] ME m m . .H.» \J. .; L7LJlJWEI§E
LT1223
12
1223fb
TYPICAL APPLICATIO
U
150mA Output Current Video Amp
SCHE ATIC
WW
SI PLIFIED
75Ω
75Ω
75Ω
75Ω
75Ω75Ω
75Ω
75Ω
75Ω
LT1223 • TA10
+
–
LT1223
V
IN
IN LT1010 OUT
V–
V
2k
+
75
20
V+
V–
2k
BIAS
R = 2k TO STABILIZE CIRCUIT
DIFFERENTIAL GAIN = 1%
DIFFERENTIAL PHASE = 1°
f
Ω
Ω
LT1223 • TA01
BIAS
3
4
6
7
8
1
5
10k
15k
BIAS
2
74': am asca ‘ n 52 no)" 3 \ aux, m (oznainm) 06715" / an 025 (0350 um) OBSOLETE PACKAGE
LT1223
13
1223fb
PACKAGE DESCRIPTIO
U
J8 Package
8-Lead CERDIP (Narrow .300 Inch, Hermetic)
(Reference LTC DWG # 05-08-1110)
OBSOLETE PACKAGE
J8 0801
.014 – .026
(0.360 – 0.660)
.200
(5.080)
MAX
.015 – .060
(0.381 – 1.524)
.125
3.175
MIN
.100
(2.54)
BSC
.300 BSC
(7.62 BSC)
.008 – .018
(0.203 – 0.457) 0° – 15°
.005
(0.127)
MIN
.405
(10.287)
MAX
.220 – .310
(5.588 – 7.874)
1234
87
65
.025
(0.635)
RAD TYP
.045 – .068
(1.143 – 1.650)
FULL LEAD
OPTION
.023 – .045
(0.584 – 1.143)
HALF LEAD
OPTION
CORNER LEADS OPTION
(4 PLCS)
.045 – .065
(1.143 – 1.651)
NOTE: LEAD DIMENSIONS APPLY TO SOLDER DIP/PLATE
OR TIN PLATE LEADS
sun 7 325 (7 52D 7 a 255) 0037 ms 7 (02037038!) was 325,m5 on 889' [a 25570 3m 14 L7LJlJWEI§E
LT1223
14
1223fb
N8 Package
8-Lead PDIP (Narrow .300 Inch)
(Reference LTC DWG # 05-08-1510)
PACKAGE DESCRIPTIO
U
N8 1002
.065
(1.651)
TYP
.045 – .065
(1.143 – 1.651)
.130 ± .005
(3.302 ± 0.127)
.020
(0.508)
MIN
.018 ± .003
(0.457 ± 0.076)
.120
(3.048)
MIN
12 34
87 65
.255 ± .015*
(6.477 ± 0.381)
.400*
(10.160)
MAX
.008 – .015
(0.203 – 0.381)
.300 – .325
(7.620 – 8.255)
.325 +.035
–.015
+0.889
–0.381
8.255
()
NOTE:
1. DIMENSIONS ARE INCHES
MILLIMETERS
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm)
.100
(2.54)
BSC
m 245 Mm Jflfi; RECOMMENDED SOLDER PAD LAV am, 020 w 254 7 n 508) nus, am (a 203 7 u 254) X45"~>‘ e ms 7 use (043571270) HHHH 0537 059 a 345 mime 9‘ ‘9 ‘ (massinm) TVP mlmmalmn mvmshed by Lmeav Tecnnnlagy empammn \5 hehaved m be mums and vename Hnwevev nu rasvansmmly .s assumed my us use Lmeav Tecnnnlagy empammn makes nu vepvesanr mmnmazmamzanunnemanamscumnsasaascnneahemnwunmmmnqeunemsunqpa‘enmgms
LT1223
15
1223fb
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
PACKAGE DESCRIPTIO
U
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 on existing patent rights.
.016 – .050
(0.406 – 1.270)
.010 – .020
(0.254 – 0.508)× 45°
0°– 8° TYP
.008 – .010
(0.203 – 0.254)
SO8 0303
.053 – .069
(1.346 – 1.752)
.014 – .019
(0.355 – 0.483)
TYP
.004 – .010
(0.101 – 0.254)
.050
(1.270)
BSC
1234
.150 – .157
(3.810 – 3.988)
NOTE 3
8765
.189 – .197
(4.801 – 5.004)
NOTE 3
.228 – .244
(5.791 – 6.197)
.245
MIN .160 ±.005
RECOMMENDED SOLDER PAD LAYOUT
.045 ±.005
.050 BSC
.030 ±.005
TYP
INCHES
(MILLIMETERS)
NOTE:
1. DIMENSIONS IN
2. DRAWING NOT TO SCALE
3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)
L7LJlJWEI§E
LT1223
16
1223fb
RELATED PARTS
PART NUMBER DESCRIPTION COMMENTS
LT1206 250mA/60MHz Current Feedback Amplifier 900V/µs, Shutdown
LT1395 400MHz Current Feedback Amplifier 800V/µs, 4.6mA Supply Current, SOT-23 Package
LT1497 Dual 125mA, 50MHz Current Feedback Amplifier 900V/µs, 7mA Supply Current
LT6210/LT6211 Single/Dual Programmable Supply Current, Rail-to-Rail C-LoadTM Stable, 200MHz, 700V/µs
Output
C-Load is a trademark of Linear Technology Corporation.
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507
●
www.linear.com
© LINEAR TECHNOLOGY CORPORATION 1992
LT/LT 0605 REV B • PRINTED IN USA