Fig. 4. Transistor counts and energy consumption for p-bit and RNG implementations.

The digital p-bits and PRNGs are synthesized by the ASAP7 PDK and simulated in HSPICE in transistor-level simulations. a Transistor count for p-bits and RNGs and (b) Energy Consumption per random bit of p-bits and RNGs. The PRNGs are 32-bits long and LUTs store 2⁸ words that are 32-bits long to be compared with 32-bit RNGs. The sMTJ-based p-bit result is repeated from ref. ²⁸. To activate the LUT, a periodic input signal with low inputs to the p-bit has been used. See the text and Supplementary Note XV for details on the energy calculation.