THS4531_15 Datasheet, PDF (32/55 Pages) Texas Instruments – Ultra Low Power, Rail-to-Rail Output, Fully-Differential Amplifier

THS4531
SLOS358B – SEPTEMBER 2011 – REVISED MARCH 2012
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APPLICATION CIRCUITS
The following circuits show application information for the THS4531. For simplicity, power supply decoupling
capacitors are not shown in these diagrams – please see the EVM and Layout Recommendations section for
recommendations. For more detail on the use and operation of fully differential op amps refer to application
report “Fully-Differential Amplifiers” SLOA054D.
Differential Input to Differential Output Amplifier
The THS4531 is a fully differential op amp and can be used to amplify differential input signals to differential
output signals. A basic block diagram of the circuit is shown in Figure 74 (V_OCM and PD inputs not shown). The
gain of the circuit is set by R_F divided by R_G.
R_G
R_F
V_IN+
V_OUT±
Differential
Input
V_S+
+
±
Differential
Output
THS4531
R_G
V_IN±
V_S±
R_F
V_OUT+
Figure 74. Differential Input to Differential Output Amplifier
Single-Ended Input to Differential Output Amplifier
The THS4531 can also be used to amplify and convert single-ended input signals to differential output signals. A
basic block diagram of the circuit is shown in Figure 75 (V_OCM and PD inputs not shown). The gain of the circuit
is again set by R_F divided by R_G.
R_G
R_F
V_IN+
V_OUT–
Single-Ended
Input
V_S+
+
–
Differential
Output
THS4531
V_S–
R_G
R_F
V_OUT+
Figure 75. Single-Ended Input to Differential Output Amplifier
Differential Input to Single-Ended Output Amplifier
Fully differential op amps like the THS4531 are not recommended for differential to single-ended conversion.
This application is best performed with an instrumentation amplifier or with a standard op amp configured as a
classic differential amplifier. See application section of the OPA835 data sheet (SLOS713).
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