LTC6257_15 Datasheet, PDF (15/24 Pages) Linear Technology – 6.5MHz, 65A Power Efficient Rail-to-Rail I/O Op Amps

LTC6255/LTC6256/LTC6257
Typical Applications
200kHz 130µA Gain-of-100 Amplifier
0.9V
V_IN
+
1/2 LTC6256
–
–0.9V
+
1/2 LTC6256
–
V_OUT
90.9k
90.9k
10k
10k
625567 F03a
Frequency Response of 40dB
Gain Amplifier
50
40
30
20
10
0
–10
–20
–30
–40
–50
10 100 1k 10k 100k 1M 10M
FREQUENCY (Hz)
625567 F03b
Figure 3. Gain of 100 Amplifier (3dB Bandwidth of 200kHz on 130µA Supply Current)
LTC6255 Very Low Power 2nd Order Lowpass Filter
The LTC6256 circuit shown in Figure 4 is a 2nd order,
100kHz, Butterworth lowpass filter. The filter’s differential
output maximizes the dynamic range in very low voltage
operation. A general 2nd order lowpass circuit is shown in
Figure  5 with the equations to calculate the RC components
for cutoff frequencies up to 100kHz for a Butterworth or a
Bessel approximation (a Bessel lowpass filter has very low
transient response overshoot). In addition the equations
for a 4th order lowpass filter are provided to calculate the
RC components for two cascaded 2nd order sections.
A, 1.8V, 140µA, 100kHz, Lowpass Filter
(Single-Ended Input and Differential Output)
2.49k
V_IN
2.49k
10k
1000pF
100pF
1.8V _0.1µF
2– ⁸
1/2 LTC6256 ¹
3+
100k
1.8V
100k
10µF
2.49k
2.49k
6_–
1/2 LTC6256 ⁷
5₊
4
V_OUT–
V_OUT+
625567 F04a
Figure 4
6
0
–6
–12
–18
–24
–30
–36
–42
10k
Frequency Response
100k
FREQUENCY (Hz)
1M
625567 F04b
625567fb
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