LT1793
Low Noise,
Picoampere Bias Current,
JFET Input Op Amp
FEATURES
s
s
s
s
s
s
s
s
s
DESCRIPTIO
Input Bias Current, Warmed Up: 10pA Max
100% Tested Low Voltage Noise: 8nV/√Hz Max
A Grade 100% Temperature Tested
Offset Voltage Over Temp: 1mV Max
Input Resistance: 10
13
Ω
Very Low Input Capacitance: 1.5pF
Voltage Gain: 1 Million Min
Gain-Bandwidth Product: 4.2MHz Typ
Guaranteed Specifications with
±5V
Supplies
APPLICATIO S
s
s
s
s
s
s
Photocurrent Amplifiers
Hydrophone Amplifiers
High Sensitivity Piezoelectric Accelerometers
Low Voltage and Current Noise Instrumentation
Amplifier Front Ends
Two and Three Op Amp Instrumentation Amplifiers
Active Filters
, LTC and LT are registered trademarks of Linear Technology Corporation.
The LT
®
1793 achieves a new standard of excellence in
noise performance for a JFET op amp. For the first time low
voltage noise (6nV/√Hz) is simultaneously offered with
extremely low current noise (0.8fA/√Hz), providing the
lowest total noise for high impedance transducer applica-
tions. Unlike most JFET op amps, the very low input bias
current (3pA typ) is maintained over the entire common
mode range which results in an extremely high input resis-
tance (10
13
Ω).
When combined with a very low input ca-
pacitance (1.5pF) an extremely high input impedance
results, making the LT1793 the first choice for amplifying
low level signals from high impedance transducers. The
low input capacitance also assures high gain linearity when
buffering AC signals from high impedance transducers.
The LT1793 is unconditionally stable for gains of 1 or more,
even with 1000pF capacitive loads. Other key features are
250µV V
OS
and a voltage gain over 4 million. Each indi-
vidual amplifier is 100% tested for voltage noise, slew rate
(3.4V/µs) and gain-bandwidth product (4.2MHz).
Specifications at
±5V
supply operation are also provided.
For an even lower voltage noise please see the LT1792 data
sheet.
TYPICAL APPLICATIO
Low Noise Light Sensor with DC Servo
C1
2pF
TOTAL 1kHz VOLTAGE NOISE DENSITY (nV/√Hz)
10k
V
+
R3
1k
LT1097
2N3904
HAMAMATSU
S1336-5BK
(908) 231-0960
V
–
R5
10k
R4
1k
1793 TA01
V
–
R2C2 > C1R1
C
D
= PARASITIC PHOTODIODE CAPACITANCE
V
OUT
= 100mV/µWATT FOR 200nm WAVE LENGTH
330mV/µWATT FOR 633nm WAVE LENGTH
–
C
D
D1
1N914
+
+
D2
1N914
3
–
2
7
LT1793
4
V
–
R1
1M
6
C2 0.022µF
V
+
V
OUT
1k
100
R2
100k
10
1
100
U
1kHz Output Voltage Noise
Density vs Source Resistance
–
+
R
SOURCE
V
N
U
U
V
N
SOURCE
RESISTANCE
ONLY
1k
T
A
= 25°C
V
S
=
±15V
10k 100k 1M 10M 100M 1G
SOURCE RESISTANCE (Ω)
V
N
=
√
(V
OP AMP
)
2
+ 4kTR
S
+ 2qI
B
R
S2
1793 TA02
1
LT1793
ABSOLUTE
AXI U
RATI GS
Supply Voltage .....................................................
±20V
Differential Input Voltage ......................................
±40V
Input Voltage (Equal to Supply Voltage) ...............
±20V
Output Short-Circuit Duration ........................ Indefinite
Operating Temperature Range ............... – 40°C to 85°C
PACKAGE/ORDER I FOR ATIO
TOP VIEW
V
OS
ADJ 1
– IN A 2
+ IN A 3
V
–
4
N8 PACKAGE
8-LEAD PDIP
T
JMAX
= 150°C,
θ
JA
= 80°C/W
A
ORDER PART
NUMBER
8 NC
7 V
+
6 OUT
5 V
OS
ADJ
LT1793ACN8
LT1793CN8
LT1793AIN8
LT1793IN8
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
SYMBOL
V
OS
I
OS
I
B
e
n
PARAMETER
Input Offset Voltage
V
S
=
±5V
Input Offset Current
Input Bias Current
Input Noise Voltage
Input Noise Voltage Density
i
n
R
IN
Input Noise Current Density
Input Resistance
Differential Mode
Common Mode
Input Capacitance
V
S
=
±5V
Input Voltage Range (Note 5)
Common Mode Rejection Ratio
Power Supply Rejection Ratio
V
CM
= –10V to 13V
T
A
= 25°C, V
S
=
±15V,
V
CM
= 0V, unless otherwise noted.
LT1793AC/LT1793AI
MIN
TYP
MAX
0.25
0.45
1.5
0.5
3
1
2.4
11.5
6
0.8
10
14
10
13
1.5
2.0
13.0
– 10.5
83
85
13.5
– 11.0
102
98
13.0
– 10.5
81
83
8
0.8
1.4
7
2
10
3
LT1793C/LT1793I
MIN
TYP
MAX
0.25
0.45
2.5
0.7
4.0
1.5
2.4
11.5
6
1
10
14
10
13
1.5
2.0
13.5
– 11.0
96
95
8
0.9
1.6
15
4
20
5
UNITS
mV
mV
pA
pA
pA
pA
µV
P-P
nV/√Hz
nV/√Hz
fA/√Hz
Ω
Ω
pF
pF
V
V
dB
dB
CONDITIONS (Note 2)
Warmed Up (Note 3)
T
J
= 25°C (Note 6)
Warmed Up (Note 3)
T
J
= 25°C (Note 6)
0.1Hz to 10Hz
f
O
= 10Hz
f
O
= 1000Hz
f
O
= 10Hz, f
O
= 1kHz (Note 4)
V
CM
= –10V to 13V
C
IN
V
CM
CMRR
PSRR
V
S
=
±4.5V
to
±
20V
2
U
U
W
W W
U
W
(Note 1)
Specified Temperature Range
Commercial (Note 8) ......................... – 40°C to 85°C
Industrial ........................................... – 40°C to 85°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec) ................ 300°C
TOP VIEW
V
OS
ADJ 1
–IN A 2
+IN A 3
V
–
4
A
ORDER PART
NUMBER
8 NC
7 V+
6 OUT
5 V
OS
ADJ
LT1793ACS8
LT1793CS8
LT1793AIS8
LT1793IS8
S8 PART MARKING
1793A
1793
1793AI
1793I
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 160°C,
θ
JA
= 190°C/W
LT1793
ELECTRICAL CHARACTERISTICS
SYMBOL
A
VOL
V
OUT
SR
GBW
I
S
PARAMETER
Large-Signal Voltage Gain
Output Voltage Swing
Slew Rate
Gain-Bandwidth Product
Supply Current
V
S
=
±5V
Offset Voltage
Adjustment Range
T
A
= 25°C, V
S
=
±15V,
V
CM
= 0V, unless otherwise noted.
LT1793AC/LT1793AI
MIN
TYP
MAX
1000
500
±13.0
±12.0
2.3
2.5
4500
3500
±13.2
±12.3
3.4
4.2
4.2
4.2
13
5.20
5.15
LT1793C/LT1793I
MIN
TYP
MAX
900
400
±13.0
±12.0
2.3
2.5
4400
3000
±13.2
±12.3
3.4
4.2
4.2
4.2
13
5.20
5.15
UNITS
V/mV
V/mV
V
V
V/µs
MHz
mA
mA
mV
CONDITIONS (Note 2)
V
O
=
±12V,
R
L
= 10k
V
O
=
±10V,
R
L
= 1k
R
L
= 10k
R
L
= 1k
R
L
≥
2k (Note 7)
f
O
= 100kHz
R
POT
(to V
EE
) = 10k
The
q
denotes specifications which apply over the temperature range 0°C
≤
T
A
≤
70°C, otherwise specifications are at T
A
= 25°C.
V
S
=
±15V,
V
CM
= 0V, unless otherwise noted. (Note 9)
SYMBOL
V
OS
∆V
OS
∆Temp
I
OS
I
B
V
CM
CMRR
PSRR
A
VOL
V
OUT
SR
GBW
I
S
PARAMETER
Input Offset Voltage
V
S
=
±5V
Average Input Offset
Voltage Drift
Input Offset Current
Input Bias Current
Input Voltage Range (Note 5)
Common Mode Rejection Ratio
Power Supply Rejection Ratio
Large-Signal Voltage Gain
Output Voltage Swing
Slew Rate
Gain-Bandwidth Product
Supply Current
V
S
=
±5V
V
CM
= –10V to 12.9V
V
S
=
±4.5V
to
±
20V
V
O
=
±12V,
R
L
= 10k
V
O
=
±10V,
R
L
= 1k
R
L
= 10k
R
L
= 1k
R
L
≥
2k (Note 7)
f
O
= 100kHz
(Note 6)
CONDITIONS (Note 2)
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
LT1793AC
MIN
TYP
MAX
0.50
0.75
5
15
130
12.9
– 10.0
79
83
900
500
13.4
– 10.8
100
97
3600
2600
1.0
1.6
13
100
400
LT1793C
MIN
TYP
MAX
1.0
1.6
8
20
150
12.9
– 10.0
77
81
800
400
13.4
– 10.8
95
94
3400
2400
3.5
4.2
50
130
500
UNITS
mV
mV
µV/°C
pA
pA
V
V
dB
dB
V/mV
V/mV
V
V
V/µs
MHz
±12.9 ±13.2
±11.9 ±12.15
2.2
2.2
3.3
3.3
4.2
4.2
5.30
5.25
±12.9 ±13.2
±11.9 ±12.15
2.2
2.2
3.3
3.3
4.2
4.2
5.30
5.25
mA
mA
3
LT1793
The
q
denotes specifications which apply over the temperature range
– 40°C
≤
T
A
≤
85°C. V
S
=
±15V,
V
CM
= 0V, unless otherwise noted. (Notes 8, 9)
SYMBOL
V
OS
∆V
OS
∆Temp
I
OS
I
B
V
CM
CMRR
PSRR
A
VOL
V
OUT
SR
GBW
I
S
PARAMETER
Input Offset Voltage
V
S
=
±5V
Average Input Offset
Voltage Drift
Input Offset Current
Input Bias Current
Input Voltage Range (Note 5)
Common Mode Rejection Ratio
Power Supply Rejection Ratio
Large-Signal Voltage Gain
Output Voltage Swing
Slew Rate
Gain-Bandwidth Product
Supply Current
V
S
=
±5V
V
CM
= –10V to 12.6V
V
S
=
±4.5V
to
±
20V
V
O
=
±12V,
R
L
= 10k
V
O
=
±10V,
R
L
= 1k
R
L
= 10k
R
L
= 1k
R
L
≥
2k
f
O
= 100kHz
(Note 6)
CONDITIONS (Note 2)
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
ELECTRICAL CHARACTERISTICS
LT1793AC/LT1793AI
MIN
TYP
MAX
0.65
1.00
5
80
700
12.6
– 10.0
78
81
850
400
±12.8
±11.8
2.1
2
13.0
– 10.5
99
96
3300
2200
±13.1
±12.1
3.2
3.1
4.2
4.2
5.40
5.35
1.3
1.9
13
300
2400
LT1793C/LT1793I
MIN
TYP
MAX
1.6
2.0
9
100
800
12.6
– 10.0
76
79
750
300
±12.8
±11.8
2.1
2
13.0
– 10.5
94
93
3000
2000
±13.1
±12.1
3.2
3.1
4.2
4.2
5.40
5.35
4.8
5.5
50
400
3000
UNITS
mV
mV
µV/°C
pA
pA
V
V
dB
dB
V/mV
V/mV
V
V
V/µs
MHz
mA
mA
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
Typical parameters are defined as the 60% yield of parameter
distributions of individual amplifiers.
Note 3:
I
B
and I
OS
readings are extrapolated to a warmed-up temperature
from 25°C measurements and 32°C characterization data.
Note 4:
Current noise is calculated from the formula:
i
n
= (2qI
B
)
1/2
where q = 1.6 • 10
–19
coulomb. The noise of source resistors up to 200M
swamps the contribution of current noise.
Note 5:
Input voltage range functionality is assured by testing offset
voltage at the input voltage range limits to a maximum of 2.3mV
(A grade) to 2.8mV (C grade).
Note 6:
This parameter is not 100% tested.
Note 7:
Slew rate is measured in A
V
= –1; input signal is
±7.5V,
output
measured at
±2.5V.
Note 8:
The LT1793AC and LT1793C are guaranteed to meet specified
performance from 0°C to 70°C and are designed, characterized and
expected to meet these extended temperature limits, but are not tested at
– 40°C and 85°C. The LT1793I is guaranteed to meet the extended
temperature limits. The LT1793AC and LT1793AI grade are 100%
temperature tested for the specified temperature range.
Note 9:
The LT1793 is measured in an automated tester in less than one
second after application of power. Depending on the package used, power
dissipation, heat sinking, and air flow conditions, the fully warmed-up chip
temperature can be 10°C to 50°C higher than the ambient temperature.
4
LT1793
TYPICAL PERFOR A CE CHARACTERISTICS
0.1Hz to 10Hz Voltage Noise
50
RMS VOLTAGE NOISE DENSITY (nV/√Hz)
VOLTAGE NOISE (1µV/DIV)
PERCENT OF UNITS (%)
0
2
4
6
TIME (SEC)
Voltage Noise
vs Chip Temperature
10
V
+
0
–0.5
9
COMMON MODE LIMIT (V)
REFERRED TO POWER SUPPLY
–1.0
–1.5
–2.0
V
+
= 5V TO 20V
COMMON MODE REJECTION RATIO (dB)
VOLTAGE NOISE (AT 1kHz) (nV/√Hz)
V
S
=
±15V
8
7
6
5
4
3
2
–75 –50 –25 0
25 50 75
TEMPERATURE (°C)
100 125
1793 G04
Power Supply Rejection Ratio
vs Frequency
120
POWER SUPPLY REJECTION RATIO (dB)
T
A
= 25°C
100
+PSRR
VOLTAGE GAIN (dB)
180
160
140
120
100
80
60
40
20
0
VOLTAGE GAIN (dB)
80
–PSRR
60
40
20
0
10
100
1k
10k 100k
FREQUENCY (Hz)
U W
8
10
1793 G01
1kHz Input Noise Voltage
Distribution
100
T
A
= 25°C
V
S
=
±15V
510 OP AMPS TESTED
Voltage Noise vs Frequency
T
A
= 25°C
V
S
=
±15V
40
30
10
1/f CORNER
30Hz
20
10
0
4.2 4.6 5.0 5.4 5.8 6.2 6.6 7.0 7.4 7.8 8.2
INPUT VOLTAGE NOISE (nV/√Hz)
1793 G02
1
1
10
100
1k
FREQUENCY (Hz)
10k
1793 G03
Common Mode Limit
vs Temperature
120
100
80
60
40
20
0
–20
60
100
20
TEMPERATURE (°C)
140
1793 G05
Common Mode Rejection Ratio
vs Frequency
T
A
= 25°C
V
S
=
±
15V
4.0
3.5
3.0
2.5
V
–
= – 5V TO – 20V
V
–
+2.0
–60
1k
10k
100k
1M
FREQUENCY (Hz)
10M
1793 G06
Voltage Gain vs Frequency
T
A
= 25°C
V
S
=
±15V
C
L
= 10pF
Gain and Phase Shift
vs Frequency
50
40
30
PHASE
20
10
GAIN
0
–10
180
200
100
1793 G09
T
A
= 25°C
V
S
=
±15V
C
L
= 10pF
80
100
PHASE SHIFT (DEG)
120
140
160
1M
10M
1793 G07
– 20
0.01
1
10k
100
FREQUENCY (Hz)
1M
100M
1793 G08
0.1
1
10
FREQUENCY (MHz)
5
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