  The Coulomb Blockade Thermometer (CBT) is a primary thermometer for cryogenic
temperatures, with demonstrated operation from below 1 mK up to 60 K. Its
performance as a primary thermometer has been verified at temperatures from 20
mK to 200 mK at uncertainty level below 1 % (k = 2). In a new project, our aim
is to extend the metrologically verified temperature range of the primary CBT
up to 25 K. We also demonstrate close-to-ideal operation of a CBT with only two
tunnel junctions when the device is embedded in a low-impedance environment.
