Multijunction thermal converters are routinely used at many primary standards laboratories for ac voltage measurements and calibrations. After nearly two decades of inactivity, the Primary Standards Laboratory at Sandia National Laboratories has reestablished the process of fabricating silicon based multijunction thermal converters. Initial results indicate the devices perform similarly to devices fabricated circa 2001 with ac-dc differences of less than $2\ \mu \mathrm{V}/\mathrm{V}$ over the frequency range of 20 Hz to 20 kHz. From 20 kHz to 1 MHz, the ac-dc difference was higher, but remained below $200\ \mu \mathrm{V}/\mathrm{V}$ . In addition to presenting these results, new design considerations, such as high-resistivity substrates for high-frequency applications, are discussed.
