Datasheet

Single-Ended to Fully Differential Application
3-3
THS4500EVM Applications
Figure 3−2. Single Supply Operation
J2
Vout+
R2
374
W
−
Vocm
+
U1
THS4500
1
8
2
3
6
5
4
R17
0
J3
Vout−
R3
402
W
R5
392
W
C13
1
m
F
R4
392
W
+VS
TP1
Vocm
C2 0
J1
Vin−
R6 0
R1
56.2
W
C1 0
R7 0
Figure 3−3. Output of an AC-Coupled, Single-Supply Application
3
2
1
0
−1
0 500 n 1 Ω
t − Time − s
Volts
Note that a small offset is present on the input voltage. This is caused by a
voltage divider formed by R2 + R4 and the parallel combination of R1 and
the source resistance of the signal generator.
This application circuit has interaction between R
source
, R
termination
, and R
g
.
Texas Instruments has provided an engineer design utility to facilitate the
design of these circuits. Engineer design utilities are available on the Ampli-
fiers and Comparators section of the Analog and Mixed Signal portion of
the TI web page.
The designer should be aware that each individual feedback path is an in-
verting path. There is no non-inverting gain circuit for fully differential amps.
The designer should also be aware that the gain is affected by the open
loop characteristic of the FDA, the same assingle-ended op-amps. If there
is sufficient safety margin between the closed loop response and open loop
response of the FDA (40 dB or more), the error contribution from the open
loop response of the FDA is negligible and can be ignored.