THS4505 Datasheet, PDF (24/38 Pages) Texas Instruments – WIDEBAND, LOW-DISTORTION, FULLY DIFFERENTIAL AMPLIFIERS

THS4504
THS4505
SLOS363C – AUGUST 2002 – REVISED MARCH 2004
dissipation is relatively small compared to the
maximum power dissipation rating to achieve the
best results.
• Comprehend the effect of the load impedance
seen by the fully differential amplifier when per-
forming system-level intercept point calculations.
Lighter loads (such as those presented by an
ADC) allow smaller intercept points to support the
same level of intermodulation distortion perform-
ance.
EXAMPLE ANALOG-TO-DIGITAL
CONVERTER DRIVER CIRCUITS
The THS4500 family of devices is designed to drive
high-performance ADCs with extremely high linearity,
allowing for the maximum effective number of bits at
the output of the data converter. Two representative
circuits shown below highlight single-supply operation
and split supply operation. Specific feedback resistor,
gain resistor, and feedback capacitor values are not
specified, as their values depend on the frequency of
interest. Information on calculating these values can
be found in the applications material above.
C_F
R_S
R_g
R_f
5V
V_S
R_T
5V
10 µF
+−
V_OCM
0.1 µF _Riso
IN _ADS5410
12 Bit/80 MSps
1 µF
−+
THS4503
IN
R_iso
CM
R_g
−5 V ^{10 µF 0.1 µF}
R_f
0.1 µF
C_F
Using the THS4503 With the ADS5410
Figure 79.
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C_F
R_S
R_g
R_f
5V
V_S
R_T
5V
10 µF 0.1 µF _Riso
+−
IN ^ADS5421
V_OCM
14 Bit/40 MSps
1 µF
−+
THS4501
IN
R_iso
CM
R_g
R_f
C_F
Using the THS4501 With the ADS5421
Figure 80.
0.1 µF
FULLY DIFFERENTIAL LINE DRIVERS
The THS4500 family of amplifiers can be used as
high-frequency, high-swing differential line drivers.
Their high power supply voltage rating (16.5 V
absolute maximum) allows operation on a single 12-V
or a single 15-V supply. The high supply voltage,
coupled with the ability to provide differential outputs
enables the ability to drive 26 V_PP into reasonably
heavy loads (250 Ω or greater). The circuit in
Figure 81 illustrates the THS4500 family of devices
used as high speed line drivers. For line driver
applications, close attention must be paid to thermal
design constraints due to the typically high level of
power dissipation.
R_S
C_{G Rg}
R_f
V_S
R_T
15 V
R_iso ^CS
V_OCM
+−
THS4504
V_DD
R_L
0.1 µF
−+
R_{iso CS}
R_f
R_g
C_G
V_OD = 26 V_PP
Fully Differential Line Driver With High Output Swing
Figure 81.
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