LT1793_15 Datasheet, PDF (1/12 Pages) Linear Technology – Low Noise, Picoampere Bias Current, JFET Input Op Amp

FEATURES
s _{Input Bias Current, Warmed Up: 10pA Max}
s _{100% Tested Low Voltage Noise: 8nV/√Hz Max}
s _{A Grade 100% Temperature Tested}
s _{Offset Voltage Over Temp: 1mV Max}
s _{Input Resistance: 10}¹³_Ω
s _{Very Low Input Capacitance: 1.5pF}
s _{Voltage Gain: 1 Million Min}
s _{Gain-Bandwidth Product: 4.2MHz Typ}
s _{Guaranteed Specifications with ±5V Supplies}
U
APPLICATIO S
s _{Photocurrent Amplifiers}
s _{Hydrophone Amplifiers}
s _{High Sensitivity Piezoelectric Accelerometers}
s _{Low Voltage and Current Noise Instrumentation}
Amplifier Front Ends
s _{Two and Three Op Amp Instrumentation Amplifiers}
s _{Active Filters}
, LTC and LT are registered trademarks of Linear Technology Corporation.
LT1793
Low Noise,
Picoampere Bias Current,
JFET Input Op Amp
DESCRIPTIO
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 (10¹³â„¦). 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
D2
1N914
C_D
2N3904
V⁺
2–
7
6
LT1793
3+
4
V^–
D1
1N914
R3
1k
R1
1M
C2 0.022µF
V⁺
R2
100k
LT1097
HAMAMATSU
S1336-5BK
[phone]
R5
10k
V^–
R4
1k
R2C2 > C1R1
V^–
1793 TA01
C_D = PARASITIC PHOTODIODE CAPACITANCE
V_OUT = 100mV/µWATT FOR 200nm WAVE LENGTH
330mV/µWATT FOR 633nm WAVE LENGTH
V_OUT
1kHz Output Voltage Noise
Density vs Source Resistance
10k
–
V_N
1k
+
R_SOURCE
100
10 V_N
SOURCE
RESISTANCE
ONLY
T_A = 25°C
V_S = ±15V
1
100 1k 10k 100k 1M 10M 100M 1G
SOURCE RESISTANCE (Ω)
V_N = √(V_{OP AMP})² + 4kTR_S + 2qI_BR_S2
1793 TA02
1