OPA2652
www.ti.com
SBOS125A–JUNE 2000–REVISED MAY 2006
Video Line Driver
C2
Figure 32 shows the OPA2652 used as a video line
driver. Its outstanding differential gain and phase
allow it to be used in studio equipment, while its low
cost and SOT23-8 package option also support
consumer applications.
C1
402W
402W
VIN
VOUT
+5V
+5V
1/2
OPA2652
Video
Input
75.0W
Video
1/2
OPA2652
75.0W
Output
402W
-5V
-5V
402W
402W
Figure 34. Inverting Bandpass Filter
DESIGN-IN TOOLS
Figure 32. Video Line Driver
Demonstration Fixtures
Two printed circuit boards (PCBs) are available to
assist in the initial evaluation of circuit performance
using the OPA2652 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 Table 1.
Pulse Delay Circuit
Figure 33 shows the OPA2652 used in a pulse delay
circuit. This circuit cascades the two op amps in the
OPA2652, each forming a single pole, active allpass
filter. The overall gain is +1, and the overall delay
through the filter is:
Table 1. Demonstration Fixtures for the OPA2652
tGD = n(2RC), overall group delay
n = 2, the number of cascaded stages
ORDERING
NUMBER
LITERATURE
NUMBER
PRODUCT
OPA2652U
OPA2652E
PACKAGE
SO-8
DEM-OPA-SO-2A
DEM-OPA-SOT-2A
SBOU003
SBOU001
+5V
+5V
SOT23-8
C
C
VIN
The demonstration fixtures can be requested at the
Texas Instruments web site (www.ti.com) through the
OPA2652 product folder.
1/2
OPA2652
1/2
OPA2652
VO
R
R
-5V
-5V
RG
RF
Macromodels and Applications Support
402W
402W
402W
402W
Computer simulation of circuit performance using
SPICE is often useful when analyzing the
performance of analog circuits and systems. This
method is particularly true for video and RF amplifier
circuits where parasitic capacitance and inductance
can have a major effect on circuit performance.
Check the Texas Instruments web site (www.ti.com)
for available SPICE products (note that not all parts
have models). 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 characteristics. These models do not attempt
to distinguish between the package types in
small-signal AC performance.
Figure 33. Pulse Delay Circuit
RF and RG need to be equal to maintain a constant
gain magnitude. The rise and fall times of the input
pulses, tr(IN), should be slow enough to prevent
pre-shoot artifacts in the response.
tr(IN) ≥ 5RC, minimal pre-shoot
Simple Bandpass Filter
Figure 34 shows the OPA2652 used as simple
bandpass filter. The OPA2652 is well-suited for this
type of circuit because it is very stable at a noise
gain of +1.
12
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