SLOS358C September 2011 – April 2020 THS4531
The circuit shown in Figure 72 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 50 Ω and is DC coupled. RIT and RG are chosen to impedance match to 50 Ω and maintain the proper gain. To balance the amplifier, a 49.9 Ω resistor to ground is inserted across RIT on the alternate input. The output is measured using a high impedance differential probe at the summing junction of the two RO resistors, with respect to ground.