| 摘要 |
The impedance of a device under test (DUT) is measured using an AC supply. A transimpedance amplifier is formed of a resistance or capacitor network having positive and negative feedback from the output of an operational amplifier. A first resistance (R21) is between the circuit input and negative amplifier input. A second resistance (R22) is between the negative amplifier input and amplifier output. A third resistance (R23) is between ground and positive amplifier input. A fourth resistance (R24) is between positive amplifier input and amplifier output, with ratios of R21/R22 equal that of R23/R24. The network holds the current input terminal at a ground voltage and the two input terminals of the amplifier at a common finite voltage above the ground voltage. |
