Output Impedance Measurement in Power Sources and Conditioners

The internal output impedance of power sources and power conditioners has a strong impact on conducted interference in mixed-signal circuits. Also, the transient response of power sources and power conditioners in front of sudden load changes must be known to prevent voltage swings beyond the operating tolerance of the load. We propose a measurement method able to determine both the output impedance and the transient response by using an op-amp-based dynamic load. The results show that this measurement method works for devices such as linear voltage regulators, power supplies and batteries. The measurement resolution achieved with the particular devices used in our experimental setup is 40 mOmega.