Novel Impedance Standards based on Series-Connected Metal-Foil Resistors with Voltage-Supplied Encapsulations

We have developed 12.906 kΩ impedance standards based on a series-connection of four commercial encapsulated metal-foil resistors. The series-connection allows selecting single resistors whose deviation from nominal resistance value and temperature dependence have opposite sign and partially cancel each other. To avoid limitation due to the capacitances between the metal foils and their encapsulations, voltage is supplied to the encapsulations in such a way that this contribution is not only greatly reduced but that their residual cancels the residual parallel capacitance (at least partially). In this way, the total capacitance and the corresponding frequency dependence are strongly reduced, constituting excellent standards of impedance and time constant.