THS4302 Datasheet, PDF (13/23 Pages) Texas Instruments – WIDEBAND FIXED-GAIN AMPLIFIER

THS4302
www.ti.com
SLOS403G – OCTOBER 2002 – REVISED JANUARY 2005
APPLICATION INFORMATION
High-Speed Operational amplifiers
The THS4302 fixed-gain operational amplifier set new
performance levels, combining low distortion, high
slew rates, low noise, and a gain bandwidth in excess
of 2 GHz. To achieve the full performance of the
amplifier, careful attention must be paid to
printed-circuit board layout and component selection.
In addition, the devices provide a power-down mode
with the ability to save power when the amplifier is
inactive.
generator. The 50-Ω series resistor at the V_O terminal
in addition to the 50-Ω load impedance of the test
equipment, provides a 100-Ω load. The total 100-Ω
load at the output, combined with the 250-Ω total
feedback network load, presents the THS4302 with
an effective output load of 71 Ω for the circuit of
Figure 44.
INTERNAL FIXED RESISTOR VALUES
DEVICE
GAIN (V/V)
R_f
R_g
THS4302
+5
200
50
Applications Section Contents
• Wideband, Noninverting Operation
• Single Supply Operation
• Saving Power With Power-Down Functionality
• Driving an ADC With the THS4302
• Driving Capacitive Loads
• Power Supply Decoupling Techniques and
Recommendations
• Board Layout
• Printed-Circuit Board Layout Techniques for
Optimal Performance
• PowerPAD Design Considerations
• PowerPAD PCB Layout Considerations
• Thermal Analysis
• Design Tools
• Evaluation Fixtures and Application Support
Information
• Additional Reference Material
• Mechanical Package Drawings
V_S+
+
FB
22 µF
50-Ω Source
V_I
49.9 Ω
R_g
V_S−
R_f
_
+ _THS4302
47 pF
0.1 µF
30.1 Ω
V_O
100 Ω
+ 22 µF ^FB
47 pF
0.1 µF
30.1 Ω
FB = Ferrite Bead
Figure 44. Wideband, Noninverting
Gain Configuration
WIDEBAND, NONINVERTING OPERATION
The THS4302 is a fixed-gain voltage feedback oper-
ational amplifier, with power-down capability,
designed to operate from a single 3-V to 5-V power
supply.
Figure 44 is the noninverting gain configuration used
to demonstrate the typical performance curves. Most
of the curves were characterized using signal sources
with 50-Ω source impedance, and with measurement
equipment presenting a 50-Ω load impedance. In
Figure 44, the 49.9-Ω shunt resistor at the V_IN
terminal matches the source impedance of the test
SINGLE SUPPLY OPERATION
The THS4302 is designed to operate from a single
3-V to 5-V power supply. When operating from a
single power supply, care must be taken to ensure
the input signal and amplifier are biased appropriately
to allow for the maximum output voltage swing. The
circuits shown in Figure 45 demonstrate methods to
configure an amplifier in a manner conducive for
single supply operation.
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