Datasheet

12
LT1169
TYPICAL APPLICATIONS N
U
 LINEAR TECHNOLOGY CORPORATION 1994
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
●
[phone]
FAX: [phone]
●
TELEX: 499-3977
●
www.linear-tech.com
1169fa LT/TP 0198 REV A 4K • PRINTED IN USA
10Hz Fourth Order Chebyshev Lowpass Filter (0.01dB Ripple)
LT1169 • TA08
V
OUT
TYPICAL OFFSET ≈ 0.8mV
1% TOLERANCES
FOR V
IN
= 10V
P-P
, V
OUT
= –121dB AT f > 330Hz
= – 6dB AT f = 16.3Hz
LOWER RESISTOR VALUES WILL RESULT IN LOWER THERMAL NOISE AND LARGER CAPACITORS
R3
249k
C2
100nF
C1
33nF
R1
237k
V
IN
R2
237k
R6
249k
C4
330nF
5
6
–
+
1/2 LT1169
7
C3
10nF
R4
154k
R5
154k
8
1
15V
–15V
4
3
2
–
+
1/2 LT1169
1. ASSUME VOLTAGE NOISE OF LT1169 AND 51 Ω SOURCE RESISTOR = 6.1nV/√Hz
2. GAIN WITH n LT1169s IN PARALLEL = n × 200
3. OUTPUT NOISE = √n × 200 × 6.1nV/√Hz
4. INPUT REFERRED NOISE =
OUTPUT NOISE
=
6.1
nV/√Hz
 n × 200
√
n
5. NOISE CURRENT AT INPUT INCREASES
√
n TIMES
6. IF n = 5, GAIN = 1000, BANDWIDTH = 110kHz, RMS NOISE, DC TO 1MHz =
2.1µV
= 1.0µV
 
8
15V
–15V
4
8
15V
–15V
4
LT1169 • TA06
1.6k
91Ω
7
6
5
3k
1.6k
91Ω
1
2
3
–
+
A2
1/2 LT1169
–
+
1.6k
91Ω
1
2
3
A1
1/2 LT1169
10k
7
5
6
–
+
1/2 LT1169
–
+
An
1/2 LT1169
3k
3k
OUTPUT
√5
Paralleling Amplifiers to Reduce Voltage Noise
RELATED PARTS
PART NUMBER DESCRIPTION COMMENTS
LT1113 Lowest Noise Dual JFET Op Amp 4.5nV/√Hz Voltage Noise
LT1462 Micro Power Dual JFET Op Amp 3.0pA I
B
, 45µA I
SUPPLY
LT1464 Low Power Dual JFET Op Amp 3.0pA (Max) Input Bias Current