Datasheet

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APPLICATION INFORMATION
HIGH-SPEED OPERATIONAL AMPLIFIERS
INTERNAL FIXED RESISTOR VALUES
APPLICATIONS SECTION CONTENTS
_
+
THS4303
R
f
49.9 Ω
V
I
+
22 µF 47 pF 0.1 µF
V
S+
50 Ω Source
R
g
V
O
+ 22 µF 47 pF 0.1 µF
V
S−
30.1 Ω
30.1 Ω
FB
FB
FB = Ferrite Bead
49.9 Ω
50 Ω Load
WIDEBAND, NONINVERTING OPERATION
THS4303
SLOS421B – NOVEMBER 2003 – REVISED JANUARY 2005
equipment, provides a 100- Ω load. The total 100- Ω
load at the output, combined with the 500- Ω total
feedback network load, presents the THS4303 with
The THS4303 fixed gain operational amplifier set new
an effective output load of 83 Ω for the circuit of
performance levels, combining low distortion, high
Figure 43 .
slew rates, low noise, and a gain bandwidth in excess
of 1.8 GHz. To achieve the full performance of the
amplifier, careful attention must be paid to
DEVICE GAIN (V/V) R
f
R
g
printed-circuit board layout and component selection.
THS4303 +10 450 50
In addition, the devices provide a power-down mode
with the ability to save power when the amplifier is
inactive.
• Wideband, Noninverting Operation
• Single Supply Operation
• Saving Power With Power-Down Functionality
• Driving an ADC With the THS4303
• Driving Capacitive Loads
• Power Supply Decoupling Techniques and Rec-
ommendations
• Board Layout
• Printed-Circuit Board Layout Techniques for Opti-
mal Performance
• PowerPAD Design Considerations
• PowerPAD PCB Layout Considerations
• Thermal Analysis
• Design Tools
• Evaluation Fixtures and Application Support Infor-
Figure 43. Wideband, Noninverting
mation
Gain Configuration
• Additional Reference Material
• Mechanical Package Drawings
The THS4303 is a fixed gain voltage feedback
operational amplifier, with power-down capability, de-
signed to operate from a single 3-V to 5-V power
supply.
Figure 43 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 43 , the 49.9- Ω shunt resistor at the V
IN
terminal matches the source impedance of the test
generator. The 50- Ω series resistor at the V
O
terminal
in addition to the 50- Ω load impedance of the test
14