Data Sheet
OP249
APPLICATIONS INFORMATION
V+
+IN
100
90
V
OUT
–IN
10
0%
5V
1µs
A) OP249
100
90
V–
Figure 39. Simplified Schematic (1/2 OP249)
10
0%
2
5V
1µs
1/2
OP249
1
B) LT1057
3
+3V
5kΩ
Figure 41. Large-Signal Transient Response,
V = 1, VIN = 20 V p-p, ZL = 2 kΩ//200 pF, VS = 15 V
A
The OP249 was carefully designed to provide symmetrically
matched slew characteristics in both the negative and positive
directions, even when driving a large output load.
+18V
6
5
8
1/2
OP249
7
The slewing limitation of the amplifier determines the maximum
frequency at which a sinusoidal output can be obtained without
significant distortion. However, it is important to note that the
nonsymmetric slewing typical of previously available JFET
amplifiers adds a higher series of harmonic energy content to
the resulting response—and an additional dc output component.
Examples of potential problems of nonsymmetric slewing behavior
can be in audio amplifier applications, where a natural low dis-
tortion sound quality is desired and in servo or signal processing
systems where a net dc offset cannot be tolerated. The linear
and symmetric slewing feature of the OP249 makes it an ideal
choice for applications that exceed the full power bandwidth
range of the amplifier.
4
+3V
5kΩ
–18V
Figure 40. Burn-In Circuit
The OP249 represents a reliable JFET amplifier design,
featuring an excellent combination of dc precision and high
speed. A rugged output stage provides the ability to drive a
600 Ω load and still maintain a clean ac response. The OP249
features a large signal response that is more linear and symmetric
than previously available JFET input amplifiers. Figure 41
compares the large signal response of the OP249 to other
industry-standard dual JFET amplifiers.
Typically, the slewing performance of the JFET amplifier is
specified as a number of V/µs. There is no discussion on the
quality, that is, linearity and symmetry of the slewing response.
Rev. I | Page 13 of 18
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