Datasheet

APPLICATION INFORMATION
HIGH-SPEED OPERATIONAL AMPLIFIERS
WIDEBAND, INVERTING OPERATION
Applications Section Contents
WIDEBAND, NONINVERTING OPERATION
_
+
R
g
1.3 kΩ
R
T
649 Ω
100 pF
0.1 µF 6.8 µF
−V
S
−5 V
50 Ω Source
+
V
I
100 pF
0.1 µF 6.8 µF
+
+V
S
5 V
V
O
C
T
0.1 µF
R
f
1.3 kΩ
R
M
52.3 Ω
499 Ω
_
+
R
f
1.3 kΩ
49.9 Ω
100 pF
0.1 µF 6.8 µF
−V
S
−5 V
R
g
50 Ω Source
+
V
I
100 pF
0.1 µF 6.8 µF
+
+V
S
5 V
V
O
499 Ω
1.3 kΩ
SN10501
SN10502
SN10503
SLOS408B – MARCH 2003 – REVISED JANUARY 2009 .................................................................................................................................................. www.ti.com
decrease the loading effect of the feedback network
on the output of the amplifier, but this enhancement
comes at the expense of additional noise and
The SN1050x operational amplifiers are a family of
potentially lower bandwidth. Feedback-resistor values
single, dual, and triple rail-to-rail output voltage
between 1 k Ω and 2 k Ω are recommended for most
feedback amplifiers. The SN1050x family combines
situations.
both a high slew rate and a rail-to-rail output stage.
Since the SN1050x family are general-purpose,
• Wideband, Noninverting Operation
wideband voltage-feedback amplifiers, several
• Wideband, Inverting Gain Operation
familiar operational-amplifier applications circuits are
• Video Drive Circuits
available to the designer. Figure 34 shows a typical
inverting configuration where the input and output
• Single Supply Operation
impedances and noise gain from Figure 33 are
• Power Supply Decoupling Techniques and
retained in an inverting circuit configuration. Inverting
Recommendations
operation is one of the more common requirements
• Active Filtering With the SN1050x
and offers several performance benefits. The
• Driving Capacitive Loads
inverting configuration shows improved slew rates
• Board Layout
and distortion due to the pseudo-static voltage
maintained on the inverting input.
• Thermal Analysis
• Additional Reference Material
• Mechanical Package Drawings
The SN1050x is a family of unity gain stable
rail-to-rail output voltage feedback operational
amplifiers designed to operate from a single 3-V to
15-V power supply.
Figure 33 is the noninverting gain configuration of
2V/V used to demonstrate the typical performance
curves.
Figure 34. Wideband, Inverting Gain
Configuration
In the inverting configuration, some key design
considerations must be noted. One is that the gain
resistor (R
g
) becomes part of the signal channel input
impedance. If input impedance matching is desired
(beneficial when the signal is coupled through a
cable, twisted pair, long PC-board trace, or other
transmission-line conductors), R
g
may be set equal to
the required termination value and R
f
adjusted to give
the desired gain. However, care must be taken when
Figure 33. Wideband, Noninverting Gain
dealing with low inverting gains, because the resulting
Configuration
feedback-resistor value can present a significant load
to the amplifier output. For an inverting gain of 2,
Voltage-feedback amplifiers, unlike current-feedback
setting R
g
to 49.9 Ω for input matching eliminates the
designs, can use a wide range of resistors values to
need for R
M
but requires a 100- Ω feedback resistor.
set their gain with minimal impact on their stability
This has the advantage that the noise gain becomes
and frequency response. Larger-valued resistors
equal to 2 for a 50- Ω source impedance — the same
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Product Folder Link(s): SN10501 SN10502 SN10503