LT1792 Linear Technology, LT1792 Datasheet - Page 10

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

A
also increases the parasitic gate capacitance, which if left
unchecked, can result in increased overshoot and ring-
ing. When the feedback around the op amp is resistive
(R
and capacitance (R
tance (C
R
create excess phase shift and even oscillation. A small
capacitor (C
With R
is completely removed.
TYPICAL
10
LT1792
S
PPLICATI
F
), a pole will be created with R
and R
S
(C
IN
F
S
= 27pF). In low gain configurations and with
in the kilohm range (Figure 5), this pole can
+ C
F
) in parallel with R
B & K MODEL 4381
ACCELEROMETER
OR EQUIVALENT
A
IN
O
PPLICATI
) = R
S
U
, C
V
F
S
IN
C
S
TYPICAL OFFSET
1% TOLERANCES
FOR V
LOWER RESISTOR VALUES WILL RESULT IN LOWER THERMAL NOISE AND LARGER CAPACITORS
), and the amplifier input capaci-
F
I FOR ATIO
, the effect of the feedback pole
U
237k
IN
R1
= 10V
F
O
P-P
10Hz Fourth Order Chebyshev Lowpass Filter (0.01dB Ripple)
eliminates this problem.
F
2
3
, the source resistance
U
, V
C2
100nF
237k
249k
R2
R3
0.8mV
–
+
OUT
W
– 5V TO –15V
100M
S
R1
LT1792
5V TO 15V
= –121dB AT f > 330Hz
= – 6dB AT f = 16.3Hz
7
4
Accelerometer Amplifier with DC Servo
2
3
–
+
R3
2k
6
LT1792
6
–15V
15V
U
1250pF
7
4
2 F
C1
C2
LT1792
33nF
C1
6
+
–
2
3
154k
R4
C3
2 F
20M
18k
20M
R2
R4
R5
C4
330nF
154k
249k
R5
R6
R
S
1792 TA03
2
3
–
+
OUTPUT
R4C2 = R5C3 > R1 (1 + R2/R3) C1
OUTPUT = 0.8mV/pC* = 8.0mV/g**
DC OUTPUT 2.7mV
OUTPUT NOISE = 6nV/ Hz AT 1kHz
**g = EARTH’S GRAVITATIONAL CONSTANT
C
LT1792
*PICOCOULOMBS
S
10nF
C3
Figure 5
–
+
6
C
R
C
F
F
IN
1792 TA06
V
OUT
OUTPUT
1792 F05