THS4531_14 Datasheet, PDF (31/56 Pages) Texas Instruments – Ultra Low Power, Rail-to-Rail Output, Fully-Differential Amplifier

THS4531
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SLOS358B – SEPTEMBER 2011 – REVISED MARCH 2012
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-Ω
Test Equipment
Cal Diff Probe
R_G
R_IT
V_IN-
No Connection
49.9 Ω
Installed to Balance
Amplifier
0.22 μF
R_G
R_IT
R_F
R_O
V_S+
+
V_OCM
–
V_OUT–
THS4531
V_S–
V_OUT+
R_O
R_F
Measure With
Diff Probe Here
Figure 73. Balance Error Test Circuit
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