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THS4520 Datasheet, PDF (20/37 Pages) Texas Instruments – WIDEBAND, LOW NOISE, LOW DISTORTION FULLY DIFFERENTIAL AMPLIFIER WITH RAIL-TO-RAIL OUTPUTS | |||
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THS4520
SLOS503B â SEPTEMBER 2006 â REVISED JULY 2007
of the network analyzer is 50 â¦. RIT and RG are
chosen to impedance match to 50 â¦, and to maintain
the proper gain. To balance the amplifier, a 0.22-μF
capacitor and 49.9-⦠resistor to ground are inserted
across RIT on the alternate input.
The output is probed using a high-impedance
differential probe across the 100-⦠resistor. The gain
is referred to the amplifier output by adding back the
6-dB loss due to the voltage divider on the output.
From VIN
50 W
Source
RG
RIT
0.22 mF
49.9 W
RG
RIT
RF
VS+
THS4520
CM
VSâ
49.9 W
49.9 W 100 W
Open
0.22 mF
Output Measured
Here With High
Impedance
Differential Probe
RF
Figure 56. Frequency Response Test Circuit
S-Parameter, Slew Rate, Transient Response,
Settling Time, Output Voltage
The circuit shown in Figure 57 is used to measure
s-parameters, slew rate, transient response, settling
time, and output voltage swing.
Because S21 is measured single-ended at the load
with 50-⦠double termination, add 12 dB to see the
amplifierâs output as a differential signal.
www.ti.com
From VIN
50 â¦
Source
RG
R IT
0.22 mF
49.9 W
RG
R IT
RF
VS+
THS4520
CM
VSâ
RF
49.9 W
49.9 W
Open
0.22 mF
VOUT+ To 50 W
Test
VOUTâ Equipment
Figure 57. S-Parameter, SR, Transient Response,
Settling Time, VOUT Swing
CM Input
The circuit shown in Figure 58 is used to measure
the frequency response of the CM input. Frequency
response is measured single-ended at VOUT+ or
VOUTâ with the input injected at VIN, RCM = 0 ⦠and
RCMT = 49.9 â¦.
0.22 mF
49.9 W
0.22 mF
49.9 W
RG
RIT
RG
RIT
RF
VS+
49.9 W
THS4520 49.9 W
CM
VSâ
RF
RCM
RCMT
VOUTâ
To
50-W
Test
VOUT+ Equipment
VIN From
50-W
Source
Figure 58. CM Input Test Circuit
20
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