  We have developed novel impedance standards based on thin-film
surface-mount-device (SMD) resistors. Due to the small dimensions of such
resistors, the quantities determining its frequency dependence are very small
and can be either measured or numerically calculated. A series connection of
thin-film SMD resistors allows to further improve the dc and the ac properties.
The nominal resistance value of our application is 12.906 kohm but other values
are just as possible. At frequencies up to 2 MHz, the calculated frequency
dependence amounts to only a few parts per million of the dc value, which is
about four orders of magnitude smaller than for all conventional calculable
ac-dc resistors having a similar nominal dc value. To measure the frequency
dependence, we use a precision LCR meter for frequencies up to 2 MHz that has a
reproducibility of a few parts per million but a systematic uncertainty which
is specified by the manufacturer to increase from 300 parts per million in the
lower frequency range to 3000 parts per million at 2 MHz. Measurements of two
very different SMD-based resistance standards allows verification of the model
calculation as well as the calibration of the precision LCR meter, both with a
relative uncertainty of a few parts per million in the whole frequency range.
This boost in precision by two to three orders of magnitude enables new
applications such as the verification of conventional calculable resistance
standards, traceable calibration of high-frequency standards, and future
high-frequency measurements of the quantum Hall resistance.
