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LT1813 Dual 3mA, 100MHz, 750V/s Operational Amplifier
FEATURES
s s s s s s s s s s s s
DESCRIPTIO
100MHz Gain Bandwidth 750V/s Slew Rate 3.6mA Maximum Supply Current per Amplifier 8nV/Hz Input Noise Voltage Unity-Gain Stable 1.5mV Maximum Input Offset Voltage 4A Maximum Input Bias Current 400nA Maximum Input Offset Current 40mA Minimum Output Current, VOUT = 3V 3.5V Minimum Input CMR, VS = 5V Specified at 5V, Single 5V Available in MS8 and SO-8 Packages
The LT(R)1813 is a low power, high speed, very high slew rate operational amplifier with excellent DC performance. The LT1813 features reduced supply current, lower input offset voltage, lower input bias current and higher DC gain than other devices with comparable bandwidth. The circuit topology is a voltage feedback amplifier with the slewing characteristics of a current feedback amplifier. The output drives a 100 load to 3.5V with 5V supplies. On a single 5V supply, the output swings from 1.1V to 3.9V with a 100 load connected to 2.5V. The amplifier is stable with a 1000pF capacitive load which makes it useful in buffer and cable driver applications. The LT1813 is manufactured on Linear Technology's advanced low voltage complementary bipolar process. For higher supply voltage single, dual and quad operational amplifiers with up to 70MHz gain bandwidth, see the LT1351 through LT1365 data sheets.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
s s s s s s
Wideband Amplifiers Buffers Active Filters Video and RF Amplification Cable Drivers Data Acquisition Systems
TYPICAL APPLICATIO
232
4MHz, 4th Order Butterworth Filter
10 0
274 232 VIN 220pF 665 47pF
VOLTAGE GAIN (dB)
-10 -20 -30 -40 -50 -60 -70 -80 -90 0.1 VS = 5V VIN = 600mVP-P PEAKING < 0.12dB 1 10 FREQUENCY (MHz) 100
1813 TA02
1/2 LT1813
470pF
+
-
274
562
22pF
1/2 LT1813
VOUT
1813 TA01
U
Filter Frequency Response
U
+
-
U
1
LT1813
ABSOLUTE MAXIMUM RATINGS (Note 1)
Total Supply Voltage (V + to V -) ............................. 12.6V Differential Input Voltage (Transient Only, Note 2) ... 3V Input Voltage ........................................................... VS Output Short-Circuit Duration (Note 3) ............ Indefinite Operating Temperature Range ................ - 40C to 85C Specified Temperature Range (Notes 8, 9) ......................................... - 40C to 85C Maximum Junction Temperature ......................... 150C Storage Temperature Range .................. - 65C to 150C Lead Temperature (Soldering, 10 sec)................... 300C
PACKAGE/ORDER INFORMATION
ORDER PART NUMBER
TOP VIEW OUT A -IN A +IN A V- 1 2 3 4 8 7 6 5 V+ OUT B -IN B +IN B
LT1813DMS8*
MS8 PACKAGE 8-LEAD PLASTIC MSOP
MS8 PART MARKING LTGZ
TJMAX = 150C, JA = 250C/ W
Consult factory for Military grade parts. *See note 9.
ELECTRICAL CHARACTERISTICS
SYMBOL VOS IOS IB en in RIN CIN PARAMETER Input Offset Voltage Input Offset Current Input Bias Current Input Noise Voltage Input Noise Current Input Resistance Input Capacitance Input Voltage Range (High) Input Voltage Range (Low) CMRR PSRR AVOL VOUT IOUT ISC SR Common Mode Rejection Ratio Power Supply Rejection Ratio Large-Signal Voltage Gain Output Swing Output Current Short-Circuit Current Slew Rate Full Power Bandwidth (Note 4)
TA = 25C, VS = 5V, VCM = 0V unless otherwise noted.
MIN TYP 0.5 50 - 0.9 MAX 1.5 400 4 UNITS mV nA A nV/Hz pA/Hz M M pF - 3.5 V V dB dB V/mV V/mV V V mA mA V/s MHz
CONDITIONS
f = 10kHz f = 10kHz VCM = 3.5V Differential 3
VCM = 3.5V VS = 2V to 5.5V VOUT = 3V, RL = 500 VOUT = 3V, RL = 100 RL = 500, 30mV Overdrive RL = 100, 30mV Overdrive VOUT = 3V, 30mV Overdrive VOUT = 0V, VIN = 1V AV = - 1 (Note 5) 3V Peak (Note 6)
2
U
U
W
WW
U
W
TOP VIEW OUT A 1 -IN A 2 A +IN A 3 V- 4 B 5 6 -IN B +IN B 8 7 V+ OUT B
ORDER PART NUMBER LT1813CS8 LT1813IS8 LT1813DS8* S8 PART MARKING 1813 1813I 1813D
S8 PACKAGE 8-LEAD PLASTIC SO TJMAX = 150C, JA = 150C/ W
8 1 10 1.5 2 3.5 75 78 1.5 1.0 3.80 3.35 40 75 500 4.2 - 4.2 85 96 3.0 2.5 4.0 3.5 60 100 750 40
LT1813
ELECTRICAL CHARACTERISTICS
SYMBOL GBW tr, tf PARAMETER Gain Bandwidth Rise Time, Fall Time Overshoot Propagation Delay Output Resistance Channel Separation Supply Current
TA = 25C, VS = 5V, VCM = 0V unless otherwise noted.
MIN 75 TYP 100 2 25 2.8 0.4 90 3 MAX UNITS MHz ns % ns dB mA
CONDITIONS f = 200kHz AV = 1, 10% to 90%, 0.1V, RL = 100 AV = 1, 0.1V, RL = 100 50% VIN to 50% VOUT, 0.1V, RL = 100 AV = 1, f = 1MHz VOUT = 3V, RL = 100 Per Amplifier
RO IS
82
3.6
TA = 25C, VS = 5V, VCM = 2.5V, RL to 2.5V unless otherwise noted.
SYMBOL VOS IOS IB en in RIN CIN PARAMETER Input Offset Voltage Input Offset Current Input Bias Current Input Noise Voltage Input Noise Current Input Resistance Input Capacitance Input Voltage Range (High) Input Voltage Range (Low) Common Mode Rejection Ratio Large-Signal Voltage Gain Output Swing (High) Output Swing (Low) IOUT ISC SR GBW tr, tf Output Current Short-Circuit Current Slew Rate Full Power Bandwidth Gain Bandwidth Rise Time, Fall Time Overshoot Propagation Delay Output Resistance Channel Separation Supply Current CONDITIONS (Note 4) MIN TYP 0.7 50 -1 8 1 20 1.5 2 4 1 82 2.0 1.5 4.1 3.9 0.9 1.1 35 75 350 55 94 2.1 25 3 0.45 92 2.9 MAX 2 400 4 UNITS mV nA A nV/Hz pA/Hz M M pF V V dB V/mV V/mV V V V V mA mA V/s MHz MHz ns % ns dB mA
f = 10kHz f = 10kHz VCM = 1.5V to 3.5V Differential
3
3.5 VCM = 1.5V to 3.5V VOUT = 1.5V to 3.5V, RL = 500 VOUT = 1.5V to 3.5V, RL = 100 RL = 500, 30mV Overdrive RL = 100, 30mV Overdrive RL = 500, 30mV Overdrive RL = 100, 30mV Overdrive VOUT = 3.5V or 1.5V, 30mV Overdrive VOUT = 2.5V, VIN = 1V AV = - 1 (Note 5) 1V Peak (Note 6) f = 200kHz AV = 1, 10% to 90%, 0.1V, RL = 100 AV = 1, 0.1V, RL = 100 50% VIN to 50% VOUT, 0.1V, RL = 100 AV = 1, f = 1MHz VOUT = 1.5V to 3.5V, RL = 100 Per Amplifier 73 1.0 0.7 3.9 3.7
1.5
CMRR AVOL VOUT
1.1 1.3
25 55 200 65
RO IS
81
3.6
The q denotes the specifications which apply over the temperature range 0C TA 70C. VS = 5V, VCM = 0V unless otherwise noted (Note 9).
SYMBOL VOS IOS IB PARAMETER Input Offset Voltage Input VOS Drift Input Offset Current Input Bias Current CONDITIONS (Note 4) (Note 7) MIN
q q q q
ELECTRICAL CHARACTERISTICS
TYP 10
MAX 2 15 500 5
UNITS mV V/C nA A
3
LT1813
The q denotes the specifications which apply over the temperature range 0C TA 70C. VS = 5V, VCM = 0V unless otherwise noted (Note 9).
SYMBOL PARAMETER Input Voltage Range (High) Input Voltage Range (Low) Common Mode Rejection Ratio Power Supply Rejection Ratio Large-Signal Voltage Gain Output Swing Output Current Short-Circuit Current Slew Rate Gain Bandwidth Channel Separation Supply Current CONDITIONS
q q
ELECTRICAL CHARACTERISTICS
MIN 3.5 73 76 1.0 0.7 3.70 3.25 35 60 400 65 81
TYP
MAX - 3.5
CMRR PSRR AVOL VOUT IOUT ISC SR GBW IS
VCM = 3.5V VS = 2V to 5.5V VOUT = 3V, RL = 500 VOUT = 3V, RL = 100 RL = 500, 30mV Overdrive RL = 100, 30mV Overdrive VOUT = 3V, 30mV Overdrive VOUT = 0V, VIN = 1V AV = - 1 (Note 5) f = 200kHz VOUT, 3V, RL = 100 Per Amplifier
q q q q q q q q q q q q
4.5
UNITS V V dB dB V/mV V/mV V V mA mA V/s MHz dB mA
0C TA 70C, VS = 5V, VCM = 2.5V, RL to 2.5V unless otherwise noted (Note 9).
VOS IOS IB Input Offset Voltage Input VOS Drift Input Offset Current Input Bias Current Input Voltage Range (High) Input Voltage Range (Low) Common Mode Rejection Ratio Large-Signal Voltage Gain Output Swing (High) Output Swing (Low) IOUT ISC SR GBW IS Output Current Short-Circuit Current Slew Rate Gain Bandwidth Channel Separation Supply Current (Note 4) (Note 7)
q q q q q q
10
2.5 15 500 5 1.5
3.5 71 0.7 0.5 3.8 3.6 1.2 1.4 20 45 150 55 80 4.5
CMRR AVOL VOUT
VCM = 1.5V to 3.5V VOUT = 1.5V to 3.5V, RL = 500 VOUT = 1.5V to 3.5V, RL = 100 RL = 500, 30mV Overdrive RL = 100, 30mV Overdrive RL = 500, 30mV Overdrive RL = 100, 30mV Overdrive VOUT = 3.5V or 1.5V, 30mV Overdrive VOUT = 2.5V, VIN = 1V AV = - 1 (Note 5) f = 200kHz VOUT, 1.5V to 3.5V, RL = 100 Per Amplifier
q q q q q q q q q q q q q
mV V/C nA A V V dB V/mV V/mV V V V V mA mA V/s MHz dB mA
- 40C TA 85C. VS = 5V, VCM = 0V unless otherwise noted (Notes 8, 9).
SYMBOL VOS IOS IB PARAMETER Input Offset Voltage Input VOS Drift Input Offset Current Input Bias Current Input Voltage Range (High) Input Voltage Range (Low) CMRR PSRR Common Mode Rejection Ratio Power Supply Rejection Ratio VCM = 3.5V VS = 2V to 5.5V CONDITIONS (Note 4) (Note 7)
q q q q q q q q
MIN
TYP 10
MAX 3 30 600 6
UNITS mV V/C nA A V V dB dB
3.5 - 3.5 72 75
4
LT1813
ELECTRICAL CHARACTERISTICS
SYMBOL AVOL VOUT IOUT ISC SR GBW IS PARAMETER Large-Signal Voltage Gain Output Swing Output Current Short-Circuit Current Slew Rate Gain Bandwidth Channel Separation Supply Current
The q denotes the specifications which apply over the temperature range - 40C TA 85C. VS = 5V, VCM = 0V unless otherwise noted (Notes 8, 9).
CONDITIONS VOUT = 3V, RL = 500 VOUT = 3V, RL = 100 RL = 500, 30mV Overdrive RL = 100, 30mV Overdrive VOUT = 3V, 30mV Overdrive VOUT = 0V, VIN = 1V AV = - 1 (Note 5) f = 200kHz VOUT, 3V, RL = 100 Per Amplifier
q q q q q q q q q q
MIN 0.8 0.6 3.60 3.15 30 55 350 60 80
TYP
MAX
UNITS V/mV V/mV V V mA mA V/s MHz dB
5
mA
- 40C TA 85C, VS = 5V, VCM = 2.5V, RL to 2.5V unless otherwise noted (Notes 8, 9).
VOS IOS IB Input Offset Voltage Input VOS Drift Input Offset Current Input Bias Current Input Voltage Range (High) Input Voltage Range (Low) CMRR AVOL VOUT Common Mode Rejection Ratio Large-Signal Voltage Gain Output Swing (High) Output Swing (Low) IOUT ISC SR GBW IS Output Current Short-Circuit Current Slew Rate Gain Bandwidth Channel Separation Supply Current VCM = 1.5V to 3.5V VOUT = 1.5V to 3.5V, RL = 500 VOUT = 1.5V to 3.5V, RL = 100 RL = 500, 30mV Overdrive RL = 100, 30mV Overdrive RL = 500, 30mV Overdrive RL = 100, 30mV Overdrive VOUT = 3.5V or 1.5V, 30mV Overdrive VOUT = 2.5V, VIN = 1V AV = - 1 (Note 5) f = 200kHz VOUT, 1.5V to 3.5V, RL = 100 Per Amplifier (Note 4) (Note 7)
q q q q q q q q q q q q q q q q q q q
3.5 10 30 600 6 3.5 1.5 70 0.6 0.4 3.7 3.5 1.3 1.5 17 40 125 50 79 5
mV V/C nA A V V dB V/mV V/mV V V V V mA mA V/s MHz dB mA
Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: Differential inputs of 3V are appropriate for transient operation only, such as during slewing. Large sustained differential inputs can cause excessive power dissipation and may damage the part. Note 3: A heat sink may be required to keep the junction temperature below absolute maximum when the output is shorted indefinitely. Note 4: Input offset voltage is pulse tested and is exclusive of warm-up drift. Note 5: Slew rate is measured between 2V on the output with 3V input for 5V supplies and 2VP-P on the output with a 3VP-P input for single 5V supplies.
Note 6: Full power bandwidth is calculated from the slew rate: FPBW = SR/2VP. Note 7: This parameter is not 100% tested. Note 8: The LT1813C is guaranteed to meet specified performance from 0C to 70C and is designed, characterized and expected to meet these extended temperature limits, but is not tested at - 40C and 85C. The LT1813I is guaranteed to meet the extended temperature limits. Note 9: The LT1813D is 100% production tested at 25C. It is designed, characterized and expected to meet the 0C to 70C specifications although it is not tested or QA sampled at these temperatures. The LT1813D is guaranteed functional from -40C to 85C but may not meet those specifications.
5
LT1813 TYPICAL PERFOR A CE CHARACTERISTICS
Supply Current vs Temperature
5 PER AMPLIFIER 4
SUPPLY CURRENT (mA)
INPUT COMMON MODE RANGE (V)
V+ - 0.5
INPUT BIAS CURRENT (A)
VS = 5V 3 VS = 2.5V
2
1
0 -50 -25
50 25 0 75 TEMPERATURE (C)
Input Bias Current vs Temperature
- 0.6 - 0.7 INPUT BIAS CURRENT (A) - 0.8 - 0.9 -1.0 -1.1 -1.2 - 50 - 25 VS = 5V
INPUT VOLTAGE NOISE (nV/Hz)
100
OPEN-LOOP GAIN (dB)
50 25 75 0 TEMPERATURE (C)
Open-Loop Gain vs Temperature
75.0 72.5
OPEN-LOOP GAIN (dB)
VS = 5V VO = 3V
OUTPUT VOLTAGE SWING (V)
-1.0 -1.5 - 2.0 RL = 100
OUTPUT VOLTAGE SWING (V)
70.0 67.5 65.0 62.5 60.0 -50 -25
RL = 500
RL = 100
50 25 75 0 TEMPERATURE (C)
6
UW
100
1813 G01
Input Common Mode Range vs Supply Voltage
0
Input Bias Current vs Common Mode Voltage
TA = 25C VS = 5V
-1.0 -1.5 - 2.0 TA = 25C VOS < 1mV 2.0 1.5 1.0 0.5
- 0.5
-1.0
-1.5
125
V- 0 1 4 3 2 5 SUPPLY VOLTAGE ( V) 6 7
1813 G02
- 2.0 - 5.0
0 2.5 - 2.5 INPUT COMMON MODE VOLTAGE (V)
5.0
1813 G03
Input Noise Spectral Density
10 TA = 25C VS = 5V AV = 101 RS = 10k
Open-Loop Gain vs Resistive Load
75.0 INPUT CURRENT NOISE (pA/Hz) 72.5 70.0 VS = 5V 67.5 VS = 2.5V 65.0 62.5 60 100 TA = 25C
in 10 en 1
1
100
125
10
100
1k 10k FREQUENCY (Hz)
0.1 100k
1813 G05
1k LOAD RESISTANCE ()
10k
1813 G06
1813 G04
Output Voltage Swing vs Supply Voltage
TA = 25C - 0.5 VIN = 30mV V+ V+ RL = 500 - 0.5 -1.0 -1.5 - 2.0
Output Voltage Swing vs Load Current
VS = 5V VIN = 30mV 85C 25C - 40C
2.0 1.5 1.0 0.5 RL = 500 0 1 4 3 2 5 SUPPLY VOLTAGE ( V) 6 7
1813 G02
2.0 1.5 1.0 0.5 V- -60 -40 0 20 40 -20 OUTPUT CURRENT (mA) 60
1813 G09
RL = 100
100
125
V-
1813 G07
LT1813 TYPICAL PERFOR A CE CHARACTERISTICS
Output Short-Circuit Current vs Temperature
120
OUTPUT SHORT-CIRCUIT CURRENT (mA)
VS = 5V SOURCE
OUTPUT IMPEDANCE ()
110
OUTPUT STEP (V)
100 SINK
90
80 -50 -25
75 0 25 50 TEMPERATURE (C)
Gain and Phase vs Frequency
70 60 50 GAIN PHASE TA = 25C AV = -1 RF = RG = 500 120 100 80 60 2.5V 2.5V 20 10 0 -10 10k 100k 1M 10M FREQUENCY (Hz) 100M 5V 20 0 -20 -40 1000M
1813 G13
GAIN BANDWIDTH (MHz)
GAIN (dB)
40 30 5V
CROSSTALK (dB)
Frequency Response vs Supply Voltage, AV = 1
6 4 TA = 25C AV = 1 NO RL VS = 2.5V 8 6
VOLTAGE MAGNITUDE (dB)
VOLTAGE MAGNITUDE (dB)
VOLTAGE MAGNITUDE (dB)
2 0 -2 -4 -6 -8 -10 -12
VS = 5V
-14 1M
10M 100M FREQUENCY (Hz)
UW
100
1813 G10
1813 G16
Settling Time vs Output Step
5 4 3 2 1 0 -1 -2 -3 -4 -5 VS = 5V AV = -1 RF = 500 CF = 3pF 0.1% SETTLING 0 5 20 15 10 25 SETTLING TIME (ns) 30 35
Output Impedance vs Frequency
100 AV = 100 AV = 10 1 AV = 1
10
0.1
0.01 TA = 25C VS = 5V 100k 1M 10M FREQUENCY (Hz) 100M
1813 G12
125
0.001 10k
1813 G11
Crosstalk vs Frequency
0 -10 -20 -30 -40 -50 -60 -70 -80 -90 100k 1M 10M 100M FREQUENCY (Hz) 1000M
1813 G14
Gain Bandwidth and Phase Margin vs Temperature
115
TA = 25C AV = 10 VIN = 0dBm RL = 100
105
GBW VS = 5V
PHASE MARGIN (DEG)
PHASE (DEG)
95 GBW VS = 2.5V PHASE MARGIN VS = 5V
40
85
42
PHASE MARGIN VS = 2.5V -50 -25 50 25 0 75 TEMPERATURE (C) 100
40
38 125
1813 G15
Frequency Response vs Supply Voltage, AV = 2
12 TA = 25C AV = 2 RL = 100
Frequency Response vs Capacitive Load, AV = - 1
TA = 25C AV = -1 V = 5V 8S RF = RG = 500 NO RL 4 CL= 1000pF CL= 500pF CL= 200pF CL= 100pF CL= 50pF CL= 0
4 2 VS = 2.5V 0 -2 -4 -6 1M VS = 5V
0
-4
-8 10M 100M FREQUENCY (Hz) 500M
1813 G17
500M
1
10M FREQUENCY (Hz)
100M 200M
1813 G18
7
LT1813 TYPICAL PERFOR A CE CHARACTERISTICS
Gain Bandwidth and Phase Margin vs Supply Voltage
105 100
GAIN BANDWIDTH (MHz)
95 90 85 80
GBW RL = 500 GBW RL = 100 44 PHASE MARGIN RL = 100 PHASE MARGIN RL = 500 0 1 4 3 5 2 SUPPLY VOLTAGE (V) 6 7 42 40 38
POWER SUPPLY REJECTION RATIO (dB)
COMMON MODE REJECTION RATIO (dB)
TA = 25C
Slew Rate vs Supply Voltage
1000 TA =25C 900 AV = -1 /2 V =V 800 RIN= R S(TOTAL)500 F G = RL = 700 600 500 400 300 200 100 0 0 1 4 3 2 5 SUPPLY VOLTAGE (V) 6 7
1813 G22
SR
SLEW RATE (V/s)
350 SR + 300 SR -
SLEW RATE (V/s)
SLEW RATE (V/s)
Slew Rate vs Temperature
TOTAL HARMONIC DISTORTION + NOISE (%)
1100 1000 900 SR + VS = 5V
SLEW RATE (V/s)
800 700 600 500 400 300 200 -50 SR - VS = 2.5V SR + VS = 2.5V -25
0.005 AV = 1
OUTPUT VOLTAGE (VP-P)
SR - VS = 5V
0 75 50 25 TEMPERATURE (C)
8
UW
1813 G19
Power Supply Rejection Ratio vs Frequency
100
Common Mode Rejection Ratio vs Frequency
100 TA = 25C VS = 5V
80 +PSRR 60
TA = 25C AV = 1 VS = 5V -PSRR
80
PHASE MARGIN (DEG)
60
40
40
20
20
0 1k 10k 1M 100k FREQUENCY (Hz) 10M 100M
1813 G20
0 1k 10k 1M 100k FREQUENCY (Hz) 10M 100M
1813 G21
Slew Rate vs Supply Voltage
450 TA =25C AV = -1 V = 1V 400 RIN= R = R = 500 F G L
1200
Slew Rate vs Input Level
TA =25C AV = -1 V = 5V 1000 RS = R = R = 500 F G L 800 SR - 600
+
SR -
SR +
250
400
200 0 1 4 3 2 5 SUPPLY VOLTAGE (V) 6 7
1813 G23
200 0 1 2 4 3 5 6 INPUT LEVEL (VP-P) 7 8
1813 G24
Total Harmonic Distortion + Noise vs Frequency
0.01
Undistorted Output Swing vs Frequency
9 8 AV = - 1 AV = 1
AV = -1
7 6 5 4 3 2 1
0.002 TA = 25C VS = 5V VO = 2VP-P RL = 500 10 100 1k 10k FREQUENCY (Hz) 100k
1813 G26
0.001
100
125
0 100k
VS = 5V RL = 100 2% MAX DISTORTION 1M 10M FREQUENCY (Hz) 100M
1813 G27
1813 G25
LT1813 TYPICAL PERFOR A CE CHARACTERISTICS
2nd and 3rd Harmonic Distortion vs Frequency
-30 -40 HARMONIC DISTORTION (dB) -50 -60 -70 -80 3RD HARMONIC -90 -100 100k 2ND HARMONIC RL = 500 1M FREQUENCY (Hz) 10M
1813 G28
DIFFERENTIAL PHASE (DEG)
AV = 2 VS = 5V VO = 2VP-P 2ND HARMONIC 3RD HARMONIC RL = 100
0.1 0
OVERSHOOT (%)
Small-Signal Transient (AV = 1)
Large-Signal Transient (AV = 1)
UW
1813 G31 1813 G34
Differential Gain and Phase vs Supply Voltage
0.5 DIFFERENTIAL GAIN RL = 150 DIFFERENTIAL GAIN RL = 1k 0.5 0.4 0.3 0.2 0.1 0 4 10 8 6 TOTAL SUPPLY VOLTAGE (V) 12
1813 G29
Capacitive Load Handling
100 90 80 DIFFERENTIAL GAIN (%) 70 60 50 40 30 20 10 0 10 100 1000 CAPACITIVE LOAD (pF) 10000
1813 G30
0.4 0.3 0.2
TA = 25C VS = 5V AV = 1
DIFFERENTIAL PHASE RL = 150 DIFFERENTIAL PHASE RL = 1k
AV = -1
Small-Signal Transient (AV = -1)
Small-Signal Transient (AV = 1, CL = 100pF)
1813 G32
1813 G33
Large-Signal Transient (AV = -1)
Large-Signal Transient (AV = -1, CL = 200pF)
1813 G35
1813 G36
9
LT1813
APPLICATIONS INFORMATION
Layout and Passive Components The LT1813 amplifier is more tolerant of less than ideal layouts than other high speed amplifiers. For maximum performance (for example, fast settling) use a ground plane, short lead lengths and RF-quality bypass capacitors (0.01F to 0.1F). For high drive current applications, use low ESR bypass capacitors (1F to 10F tantalum). The parallel combination of the feedback resistor and gain setting resistor on the inverting input combine with the input capacitance to form a pole that can cause peaking or oscillations. If feedback resistors greater than 2k are used, a parallel capacitor of value CF > RG * CIN/RF should be used to cancel the input pole and optimize dynamic performance. For applications where the DC noise gain is 1 and a large feedback resistor is used, CF should be greater than or equal to CIN. An example would be an I-to-V converter. Input Considerations Each of the LT1813 amplifier inputs is the base of an NPN and PNP transistor whose base currents are of opposite polarity and provide first-order bias current cancellation. Because of variation in the matching of NPN and PNP beta, the polarity of the input current can be positive or negative. The offset current does not depend on beta matching and is well controlled. The use of balanced source resistance at each input is recommended for applications where DC accuracy must be maximized. The inputs can withstand differential input voltages of up to 3V without damage and need no clamping or source resistance for protection. Differential inputs generate the large supply currents (up to 40mA) required for high slew rates. Typically, power dissipation does not significantly increase in normal, closed-loop operation because of the low duty cycle of the transient inputs. The device should not be used as a comparator because with sustained differential inputs, excessive power dissipation may result. Slew Rate The slew rate is proportional to the differential input voltage. Highest slew rates are therefore seen in the lowest gain configurations. For example, a 5V output step in a gain of 10 has a 0.5V input step, whereas in unity gain there is a 5V input step. The LT1813 is tested for slew rate in a gain of - 1. Lower slew rates occur in higher gain configurations. Power Dissipation The LT1813 combines high speed and large output drive in a small package. It is possible to exceed the maximum junction temperature under certain conditions. Maximum junction temperature (TJ) is calculated from the ambient temperature (TA) and power dissipation (PD) as follows: LT1813CS8: TJ = TA + (PD * 150C/W) Power dissipation is composed of two parts. The first is due to the quiescent supply current and the second is due to on-chip dissipation caused by the load current. The worst-case load induced power occurs when the output voltage is at 1/2 of either supply voltage (or the maximum swing if less than 1/2 supply voltage). For each amplifier: PDMAX = (V + - V - )(ISMAX) + (V +/2)2/RL or PDMAX = (V + - V - )(ISMAX) + (V + - VOMAX)(VOMAX/RL) Capacitive Loading The LT1813 is stable with a 1000pF capacitive load which is outstanding for a 100MHz amplifier. This is accomplished by sensing the load induced output pole and adding compensation at the amplifier gain node. As the capacitive load increases, both the bandwidth and phase margin decrease so there will be peaking in the frequency domain and in the transient response. Coaxial cable can be driven directly, but for best pulse fidelity, a resistor of value equal to the characteristic impedance of the cable (i.e., 75) should be placed in series with the output. The other end of the cable should be terminated with the same value resistor to ground.
10
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W
U
U
LT1813
APPLICATIONS INFORMATION
Example: LT1813 in SO-8 at 70C, VS = 5V, RL = 100 PDMAX = (10V)(4.5mA) + (2.5V)2/100 = 108mW TJMAX = 70C + (2 * 108mW)(150C/W) = 102C Circuit Operation The LT1813 circuit topology is a true voltage feedback amplifier that has the slewing behavior of a current feedback amplifier. The operation of the circuit can be understood by referring to the Simplified Schematic. The inputs are buffered by complementary NPN and PNP emitter followers which drive a 300 resistor. The input voltage appears across the resistor generating currents that are mirrored into the high impedance node. Complementary followers form an output stage that buffers the gain node from the load. The bandwidth is set by the input resistor and the capacitance on the high impedance node. The slew rate is determined by the current available to charge the gain node capacitance. This current is the differential input voltage divided by R1, so the slew rate is proportional to the input. Highest slew rates are therefore seen in the lowest gain configurations. The RC network across the output stage is bootstrapped when the amplifier is driving a light or moderate load and has no effect under normal operation. When driving capacitive loads (or a low value resistive load) the network is incompletely bootstrapped and adds to the compensation at the high impedance node. The added capacitance slows down the amplifier which improves the phase margin by moving the unity-gain cross away from the pole formed by the output impedance and the capacitive load. The zero created by the RC combination adds phase to ensure that the total phase lag does not exceed 180 degrees (zero phase margin) and the amplifier remains stable. In this way, the LT1813 is stable with up to 1000pF capacitive loads in unity gain, and even higher capacitive loads in higher closed-loop gain configurations.
SI PLIFIED SCHEMATIC
V+
R1 300 -IN
V-
1813 SS
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 its circuits as described herein will not infringe on existing patent rights.
U
W
W
U
U
W
+IN C
RC
CC OUT
11
LT1813
TYPICAL APPLICATION
Two Op Amp Instrumentation Amplifier
R5 220 R1 10k R2 1k R4 10k
VIN
R4 1 R2 R3 R2 + R3 GAIN = 1 + + + R5 R3 2 R1 R4 TRIM R5 FOR GAIN TRIM R1 FOR COMMON MODE REJECTION BW = 1MHz
PACKAGE DESCRIPTION
MS8 Package 8-Lead Plastic MSOP
(LTC DWG # 05-08-1660)
0.118 0.004* (3.00 0.102)
8
0.193 0.006 (4.90 0.15)
1 0.040 0.006 (1.02 0.15) 0.007 (0.18) 0.021 0.006 (0.53 0.015) 0 - 6 TYP SEATING PLANE 0.012 (0.30) 0.0256 REF (0.65) BSC
* 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
RELATED PARTS
PART NUMBER LT1360/LT1361/LT1362 LT1363/LT1364/LT1365 LT1398/LT1399 DESCRIPTION Single/Dual/Quad 50MHz, 800V/s, C-LoadTM Amplifiers Single/Dual/Quad 70MHz, 1000V/s C-Load Amplifiers Dual/Triple 300MHz Current Feedback Amplifiers COMMENTS 15V Operation, 1mV Max VOS, 1A Max IB 15V Operation, 1.5mV Max VOS, 2A Max IB 4.5mA Supply Current, 80mA Output Current, Shutdown
C-Load is a trademark of Linear Technology Corporation.
12
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 q FAX: (408) 434-0507 q www.linear-tech.com
U
U
- +
-
1/2 LT1813
R3 1k
-
1/2 LT1813 VOUT
+
+
(
) = 102

1813 TA03
S8 Package 8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.189 - 0.197* (4.801 - 5.004) 8 7 6 5
76
5
0.118 0.004** (3.00 0.102)
0.228 - 0.244 (5.791 - 6.197)
0.150 - 0.157** (3.810 - 3.988)
23
4 0.034 0.004 (0.86 0.102)
1 0.010 - 0.020 x 45 (0.254 - 0.508) 0.008 - 0.010 (0.203 - 0.254) 0.053 - 0.069 (1.346 - 1.752) 0- 8 TYP 2 3 4
0.004 - 0.010 (0.101 - 0.254)
0.006 0.004 (0.15 0.102)
MSOP (MS8) 1098
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
0.016 - 0.050 (0.406 - 1.270)
0.050 (1.270) BSC
SO8 1298
1813f LT/TP 0999 4K * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 1999

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