OP467 Datasheet, PDF (13/16 Pages) Analog Devices – Quad Precision, High Speed Operational Amplifier

2.5mV
–2.5mV
0.01% 10V STEP
V_S = ؎15V
POS SLOPE
Figure 42. Instrumentation Amplifier Settling Time to
0.01% for a 10 V Step Input (Positive Slope)
TO
INPUT
2k⍀
TO
IN-AMP
OUTPUT
2k⍀
+V_S
+
+
AD9617 _1k⍀
–
–
61.9⍀
–V_S
549⍀
ERROR
TO
SCOPE
Figure 43. Settling Time Measurement Circuit
OP467
2 MHz BIQUAD BANDPASS FILTER
The circuit in Figure 44 is commonly used in medical imaging
ultrasound receivers. The 30 MHz bandwidth is sufficient to
accurately produce the 2 MHz center frequency, as the mea-
sured response shows in Figure 45. When the op amp’s band-
width is too close to the filter’s center frequency, the amplifier’s
internal phase shift causes excess phase shift at 2 MHz, which
alters the filter’s response. In fact, if the chosen op amp has a
bandwidth close to 2 MHz, the combined phase shift of the
three op amps will cause the loop to oscillate.
Careful consideration must be given to the layout of this circuit
as with any other high speed circuit.
If the phase shift introduced by the layout is large enough, it
could alter the circuit performance, or worse, it will oscillate.
C1
50pF
R6
1k⍀
R1
3k⍀
2k⍀
1/4
OP467
–+
V_IN
R2
2k⍀
–
R3
1/4
2k⍀
OP467
+
V_OUT
R4
2k⍀
–
1/4
OP467
+
C2
50pF
R5
2k⍀
–
1/4
OP467
+
Figure 44. 2 MHz Biquad Filter
0
–10
–20
–30
–40
10k
100k
1M
10M
100M
FREQUENCY – Hz
Figure 45. Biquad Filter Response
REV. C
–13–