OP275GBC 查看數據表（PDF） - Analog Devices
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OP275GBC Datasheet PDF : 12 Pages
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OP275
of the circuit and dc offset errors. If the parallel combination of
RF and RG is larger than 2␣ kΩ, then an additional resistor, RS,
should be used in series with the noninverting input. The value
of RS is determined by the parallel combination of RF and RG to
maintain the low distortion performance of the OP275.
Driving Capacitive Loads
The OP275 was designed to drive both resistive loads to 600 Ω
and capacitive loads of over 1000 pF and maintain stability.
While there is a degradation in bandwidth when driving capaci-
tive loads, the designer need not worry about device stability.
The graph in Figure 16 shows the 0 dB bandwidth of the OP275
with capacitive loads from 10 pF to 1000 pF.
10
9
8
7
6
5
4
3
2
1
0
0
200
400
600
800
1000
CLOAD – pF
Figure 16. Bandwidth vs. CLOAD
High Speed, Low Noise Differential Line Driver
The circuit of Figure 17 is a unique line driver widely used in
industrial applications. With ± 18 V supplies, the line driver can
deliver a differential signal of 30 V p-p into a 2.5 kΩ load. The
high slew rate and wide bandwidth of the OP275 combine to
yield a full power bandwidth of 130 kHz while the low noise
front end produces a referred-to-input noise voltage spectral
density of 10 nV/√Hz.
R3
2k
2
R9
50
1
3 A2
R1
2k
VIN
3
1
2 A1
R7
R4
2k
2k
R5
2k R6
R2
2k
2k
A1 = 1/2 OP275
6
R10
7
50
A3
5
R8
A2, A3 = 1/2 OP275
2k
GAIN
=
R3
R1
SET R2, R4, R5 = R1 AND R6, R7, R8 = R3
VO1
R11
1k
VO2 – VO1 = VIN
P1
10k
R12
1k
VO2
Figure 17. High Speed, Low Noise Differential Line Driver
The design is a transformerless, balanced transmission system
where output common-mode rejection of noise is of paramount
importance. Like the transformer based design, either output
can be shorted to ground for unbalanced line driver applications
without changing the circuit gain of 1. Other circuit gains can be
set according to the equation in the diagram. This allows the
design to be easily set to noninverting, inverting, or differential
operation.
A 3-Pole, 40 kHz Low-Pass Filter
The closely matched and uniform ac characteristics of the
OP275 make it ideal for use in GIC (Generalized Impedance
Converter) and FDNR (Frequency-Dependent Negative Resis-
tor) filter applications. The circuit in Figure 18 illustrates a lin-
ear-phase, 3-pole, 40 kHz low-pass filter using an OP275 as an
inductance simulator (gyrator). The circuit uses one OP275 (A2
and A3) for the FDNR and one OP275 (A1 and A4) as an input
buffer and bias current source for A3. Amplifier A4 is config-
ured in a gain of 2 to set the pass band magnitude response to
0 dB. The benefits of this filter topology over classical ap-
proaches are that the op amp used in the FDNR is not in the
signal path and that the filter’s performance is relatively insensi-
tive to component variations. Also, the configuration is such that
large signal levels can be handled without overloading any of the
the filter’s internal nodes. As shown in Figure 19, the OP275’s
symmetric slew rate and low distortion produce a clean, well-
behaved transient response.
R1
95.3kΩ
C1
2
2200pF
1
VIN
3 A1
R2
787Ω
R6
4.12kΩ
C2
2200pF
2
1
A2 3
R3
1.82kΩ
C3
2200pF
C4
5
2200pF
6 A3 7
R7
100kΩ
5
7
6 A4
R8
R9
1kΩ
1kΩ
VOUT
R4
1.87kΩ
R5
1.82kΩ
A1, A4 = 1/2 OP275
A2, A3 = 1/2 OP275
Figure 18. A 3-Pole, 40 kHz Low-Pass Filter
100
90
VOUT
10Vp-p
10kHz
10
0%
SCALE: VERTICAL–2V/ DIV
HORIZONTAL–10µs/ DIV
Figure 19. Low-Pass Filter Transient Response
–10–
REV. A
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