OP297
100
80
GAIN
OPEN-LOOP GAIN (dB)
70
1000
T
A
= 25 C
V
S
= 15V
A
VCL
= +1
V
OUT
= 100mV p-p
PHASE SHIFT (Deg)
60
40
20
0
–20
PHASE
OVERSHOOT (%)
50
40
OUTPUT IMPEDANCE ( )
V
S
= 15V
C
L
= 30pF
R
L
= 1M
60
–EDGE
100
T
A
= 25 C
V
S
= 15V
10
T
A
= –55 C
+EDGE
30
20
10
1
0.1
0.01
0.001
10
T
A
= +125 C
–40
100
0
1k
100
10k
FREQUENCY (Hz)
1M
10M
0
100
1000
LOAD CAPACITANCE (pF)
10000
100
1k
10k
100k
FREQUENCY (Hz)
1M
TPC 19. Open Loop Gain, Phase
vs. Frequency
TPC 20. Small-Signal Over-
shoot vs. Load Capacitance
TPC 21. Open Loop Output
Impedance vs Frequency
APPLICATIONS INFORMATION
Extremely low bias current over a wide temperature range makes
the OP297 attractive for use in sample-and-hold amplifiers,
peak detectors, and log amplifiers that must operate over a wide
temperature range. Balancing input resistances is unnecessary
with the OP297. Offset voltage and TCV
OS
are degraded only
minimally by high source resistance, even when unbalanced.
The input pins of the OP297 are protected against large differ-
ential voltage by back-to-back diodes and current-limiting
resistors. Common-mode voltages at the inputs are not restricted
and may vary over the full range of the supply voltages used.
The OP297 requires very little operating headroom about the
supply rails and is specified for operation with supplies as low as
2 V. Typically, the common-mode range extends to within 1 V
of either rail. The output typically swings to within 1 V of the
rails when using a 10 kΩ load.
AC PERFORMANCE
100
90
10
0%
20mV
5 s
Figure 5. Small-Signal Transient Response
(C
LOAD
= 1000 pF, A
VCL
= 1)
The OP297’s ac characteristics are highly stable over its full
operating temperature range. Unity gain small-signal response is
shown in Figure 4. Extremely tolerant of capacitive loading on
the output, the OP297 displays excellent response with 1000 pF
loads (Figure 5).
100
90
10
0%
100
90
20mV
5 s
Figure 6. Large-Signal Transient Response
(A
VCL
= 1)
10
0%
20mV
5 s
Figure 4. Small-Signal Transient Response
(C
LOAD
= 100 pF, A
VCL
= 1)
–6–
REV. E
AD [ ANALOG DEVICES ]
