OPA3682 Datasheet, PDF (15/19 Pages) Burr-Brown (TI) – Triple, Wideband, Fixed Gain BUFFER AMPLIFIER With Disable

The output resistors isolate the outputs from each other
when switching between channels. The feedback network of
the disabled channels forms part of the load seen by the
enabled amplifier, attenuating the signal slightly.
LOWPASS FILTER
The circuit in Figure 5 realizes a 7th-order Butterworth
lowpass filter with a –3dB bandwidth of 20MHz. This filter
is based on the KRC active filter topology, which uses an
amplifier with the fixed gain ≥ 1. The OPA3682 makes a good
amplifier for this type of filter. The component values have
been pre-distorted to compensate for the op amp’s parasitic
effects.
DESIGN-IN TOOLS
APPLICATIONS SUPPORT
The Burr-Brown Applications department is available for
design assistance at 1-800-548-6132 (US/Canada only). The
Burr-Brown internet web page (http://www.burr-brown.com)
has the latest data sheets and other design aids.
DEMONSTRATION BOARDS
A PC board is available to assist in the initial evaluation of
circuit performance using the OPA3682E. It is available as
a free unpopulated PC board delivered with descriptive
documentation. The summary information for this board is
shown in the table below.
PRODUCT
OPA3682E
PACKAGE
SSOP-16
DEMO
BOARD
NUMBER
DEM-OPA368xE
LITERATURE
REQUEST
NUMBER
MKT-354
Contact the Burr-Brown applications support line to request
this board.
MACROMODELS AND APPLICATIONS SUPPORT
Computer simulation of circuit performance using SPICE^®
is often useful when analyzing the performance of analog
circuits and systems. This is particularly true for video and
RF amplifier circuits where parasitic capacitance and induc-
tance can have a major effect on circuit performance. A
SPICE model for the OPA3682 is available through the
Burr-Brown Internet web page (http://www.burr-brown.com).
The Applications department is also available for design
assistance at this number. 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 dG/dφ charac-
teristics. These models do not attempt to distinguish between
the package types in their small-signal AC performance.
47.5Ω
V_IN
124Ω
120pF
82pF
1/3
OPA3682
49.9Ω
110Ω
220pF
255Ω
22pF
56pF
1/3
OPA3682
400Ω
400Ω
(open)
400Ω
400Ω
48.7Ω
180pF
95.3Ω
68pF
1/3
OPA3682
V_OUT
FIGURE 5. 7th-Order Butterworth Filter.
400Ω
400Ω
(open)
®
15
OPA3682