  We perform the characterization and modeling of a floating-gate device
realized with a commercial 350-nm CMOS technology at cryogenic temperature. The
programmability of the device offers a solution in the realization of a precise
and flexible cryogenic system for qubits control in large-scale quantum
computers. The device stores onto a floating-gate node a non-volatile charge,
which can be bidirectionally modified by Fowler-Nordheim tunneling and
impact-ionized hotelectron injection. These two injection mechanisms are
characterized and modeled in compact equations both at 300 K and 15 K. At
cryogenic temperature, we show a fine-tuning of the stored charge compatible
with the operation of a precise analog memory. Moreover, we developed accurate
simulation models of the proposed floating-gate device that set the stage for
designing a programmable analog circuit with better performances and accuracy
at a few Kelvin. This work offers a solution in the design of configurable
analog electronics to be employed for accurately read out the qubit state at
deep-cryogenic temperature.
