THS4531A Datasheet, PDF (27/51 Pages) Texas Instruments – Ultra Low Power, Rail-to-Rail Output, Fully-Differential Amplifier

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THS4531A
SLOS823A – DECEMBER 2012 – REVISED JANUARY 2013
Balance Error
The circuit shown in Figure 73 is used to measure the balance error of the main differential amplifier. A network
analyzer is used as the signal source and the measurement device. The output impedance of the network
analyzer is 50Ω and is DC coupled. R_IT and R_G are chosen to impedance match to 50Ω and maintain the proper
gain. To balance the amplifier, a 49.9Ω resistor to ground is inserted across R_IT on the alternate input. The output
is measured using a high impedance differential probe at the summing junction of the two R_O resistors, with
respect to ground.
V_IN+
Input From 50-
Test Equipment
R_G
R_F
R_O
Cal Diff Probe
V_IN-
No Connection
49.9
Installed to Balance
Amplifier
R_IT
0.22 F
R_G
R_IT
V_S+
V_OUT±
+
V_OCM
±
THS4531A
V_S±
V_OUT+
R_O
R_F
Measure With
Diff Probe Here
Figure 73. Balance Error Test Circuit
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