OPA3691 Datasheet, PDF (16/32 Pages) Burr-Brown (TI) – Triple Wideband, Current-Feedback OPERATIONAL AMPLIFIER With Disable

+5V
74HC238
D₁
D₂
Y₀
Y₁
Y₂
+5V
20Ω
1/3
OPA3691
Power-supply
decoupling not shown.
73.2Ω
191Ω
365Ω
20Ω
V_IN
1/3
68.1Ω
50Ω Load
50Ω
OPA3691
61.2Ω
274Ω
20Ω
1/3
OPA3691
20Ω
182Ω
63.4Ω
FIGURE 8. Wideband Programmable Gain.
DESIGN-IN TOOLS
DEMONSTRATION FIXTURES
Two printed circuit boards (PCBs) are available to assist in
the initial evaluation of circuit performance using the OPA3691
in its two package options. Both of these are offered free of
charge as unpopulated PCBs, delivered with a user's guide.
The summary information for these fixtures is shown in the
table below.
PRODUCT
OPA3691IDBQ
OPA3691ID
PACKAGE
ORDERING
NUMBER
SSOP-16 DEM-OPA-SSOP-3A
SO-16
DEM-OPA-SO-3A
LITERATURE
NUMBER
SBOU006
SBOU007
The demonstration fixtures can be requested at the Texas
Instruments web site (www.ti.com) through the OPA3691
product folder.
SPICE MODELS
Computer simulation of circuit performance using SPICE is
often useful when analyzing the performance of analog
circuits and systems. This is particularly true for high-speed
–5V
active devices, like the OPA3691, where parasitic capaci-
tance and inductance can have a major effect on frequency
response.
SPICE models will be available through the TI web page or
on a disk (call our Applications Department). These models
do a good job of predicting small-signal AC and transient
performance under a wide variety of operating conditions.
They do not do as well in predicting the harmonic distortion
or differential gain and phase characteristics. These models
do not distinguish between the AC performance of different
package types.
OPERATING SUGGESTIONS
SETTING RESISTOR VALUES TO
OPTIMIZE BANDWIDTH
A current-feedback op amp like the OPA3691 can hold an
almost constant bandwidth over signal gain settings with the
proper adjustment of the external resistor values. This is
shown in the Typical Characteristics; the small-signal band-
width decreases only slightly with increasing gain. These
curves also show that the feedback resistor has been changed
for each gain setting. The resistor values on the inverting side
16
OPA3691
www.ti.com
SBOS227E