SBOS968C june 2022 – july 2023 OPA186 , OPA2186 , OPA4186
PRODUCTION DATA
Figure 7-3 shows the circuit configuration for testing the EMIRR +IN. An RF source is connected to the op-amp noninverting input pin 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 can interfere with multimeter accuracy.