Hello,

You can use a noise injection circuit. See the Fig. 13 of the following paper.

S. Goel, A. Kumar and M. A. Bayoumi, "Design of Robust, Energy-Efficient Full Adders for Deep-Submicrometer Design Using Hybrid-CMOS Logic Style," in IEEE Transactions on Very Large Scale Integration (VLSI) Systems, vol. 14, no. 12, pp. 1309-1321, Dec. 2006, doi: 10.1109/TVLSI.2006.887807.