Datasheet

S-Parameter, Slew Rate, Transient Response,
5V
CM
V
IN
From
source
49.9 W
0.22 Fm
R
F
R
F
R
G
R
G
R
IT
R
IT
V
OUT+
V
OUT–
To
50-W
Test
Equipment
R
CMT
R
CM
THS4508
50-W
49.9 W
0.22 Fm
49.9 W
49.9 W
CMRR and PSRR
THS4508
CM
V
IN
R
F
R
F
R
G
R
G
R
IT
R
IT
From
50-W
Source
0.22 Fm
49.9 W
V
OUT+
Open
To50-W
Test
Equipment
5V
0.22 Fm
V
OUT-
49.9 W
49.9 W
From
50 W
Source
THS4508
CM
V
IN
CMRR
PSRR+
PSRR-
V
S+
V
S-
5V
100 W
100 W
69.8 W
348 W
348 W
49.9 W
49.9 W
Open
0.22 Fm
100 W
Output
Measured
Here
WithHigh
Impedance
Differential
Probe
CM Input
THS4508
SLAS459E – SEPTEMBER 2005 – REVISED SEPTEMBER 2008 .................................................................................................................................... www.ti.com
The 1-dB compression point is measured with a at V
OUT+
or V
OUT –
with the input injected at V
IN
, R
CM
=
spectrum analyzer with 50- Ω double termination or 0 Ω and R
CMT
= 49.9 Ω . The input impedance is
100- Ω termination as shown in Table 2 . The input measured with R
CM
= 49.9 Ω with R
CMT
= open, and
power is increased until the output is 1 dB lower than calculated by measuring the voltage drop across R
CM
expected. The number reported in the table data is to determine the input current.
the power delivered to the spectrum analyzer input.
Add 3 dB to refer to the amplifier output.
Settling Time, Output Impedance, Overdrive,
Output Voltage, and Turn-On/Off Time
The circuit shown in Figure 46 is used to measure
s-parameters, slew rate, transient response, settling
time, output impedance, overdrive recovery, output
voltage swing, and turn-on/turn-off times of the
amplifier. For output impedance, the signal is injected
at V
OUT
with V
IN
left open and the drop across the
Figure 47. CM Input Test Circuit
49.9 Ω resistor is used to calculate the impedance
seen looking into the amplifier output.
Because S
21
is measured single-ended at the load
The circuit shown in Figure 48 is used to measure the
with 50- Ω double termination, add 12 dB to refer to
CMRR and PSRR of V
S+
and V
S –
. The input is
the amplifier output as a differential signal.
switched appropriately to match the test being
performed.
Figure 46. S-Parameter, SR, Transient Response,
Figure 48. CMRR and PSRR Test Circuit
Settling Time, Z
O
, Overdrive Recovery, V
OUT
Swing, and Turn-On/Off Test Circuit
The circuit shown in Figure 47 is used to measure the
frequency response and input impedance of the CM
input. Frequency response is measured single-ended
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