  We present a measurement and analysis scheme for determining traceable
thermodynamic temperature at cryogenic temperatures using Coulomb blockade
thermometry. The uncertainty of the electrical measurement is improved by
utilizing two sampling digital voltmeters instead of the traditional lock-in
technique. The remaining uncertainty is dominated by that of the numerical
analysis of the measurement data. Two analysis methods are demonstrated:
numerical fitting of the full conductance curve and measuring the height of the
conductance dip. The complete uncertainty analysis shows that using either
analysis method the relative combined standard uncertainty (k = 1) in
determining the thermodynamic temperature in the temperature range from 20 mK
to 200 mK is below 0.5 %. In this temperature range, both analysis methods
produced temperature estimates that deviated from 0.39 % to 0.67 % from the
reference temperatures provided by a superconducting reference point device
calibrated against the Provisional Low Temperature Scale of 2000.
