SBOS947A July 2019 – June 2020 TLV2186
Figure 41 shows the circuit configuration for testing the EMIRR +IN. An RF source is connected to the op amp noninverting input terminal using a transmission line. The op amp is configured in a unity-gain buffer topology with the output connected to a low-pass filter (LPF) and a digital multimeter (DMM). A large impedance mismatch at the op amp input causes a voltage reflection; however, this effect is characterized and accounted for when determining the EMIRR IN+. The multimeter samples and measures the resulting DC offset voltage. The LPF isolates the multimeter from residual RF signals that may interfere with multimeter accuracy.