LT1792 Linear Technology, LT1792 Datasheet - Page 11

• Manufacturer Part Number: LT1792
• Description: Low Noise/ Precision/ JFET Input Op Amp
• Manufacturer: Linear Technology

TYPICAL
A
PPLICATI
HAMAMATSU
S1336-5BK
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.
O
2N3904
U
C
D
S
V
51
51
51
–
Paralleling Amplifiers to Reduce Voltage Noise
R5
1k
D2
1N914
Low Noise Light Sensor with DC Servo
3
2
3
2
3
2
R4
1k
+
–
+
–
+
–
LT1792
LT1792
LT1792
1N914
A1
A2
An
D1
–15V
15V
R2C2 > C1R1
C
V
D
O
7
4
= PARASITIC PHOTODIODE CAPACITANCE
= 100mV/ WATT FOR 200nm WAVE LENGTH
1k
1k
1k
2
3
330mV/ WATT FOR 633nm WAVE LENGTH
2pF
R3
1k
C1
–
+
6
6
6
LT1792
1k
1k
1k
1. ASSUME VOLTAGE NOISE OF LT1792 AND 51 SOURCE RESISTOR = 4.3nV/ Hz
2. GAIN WITH n LT1792s IN PARALLEL = n
3. OUTPUT NOISE = n 200 4.3nV/ Hz
4. INPUT REFERRED NOISE =
5. NOISE CURRENT AT INPUT INCREASES n TIMES
6
1M
R1
6
LT1792
V
V
+
–
7
4
0.022 F
2
3
+
–
C2
–
+
2
3
LT1792
1792 TA05
–15V
10k
15V
7
4
100k
OUTPUT NOISE
R2
n 200
6
OUTPUT
OUTPUT
200
=
4.3
n
nV/ Hz
LT1792
11
1792 TA04