An optimized back bias generator (BBG) was designed and implemented in the NS32332 32-bit microprocessor. A novel analysis method based on energy transfer in the charge pump circuit was used for better understanding of the circuit. The complete considerations, implementation, and the improved performance results are presented and discussed. The most important design consideration was to implement a very strong pump and to eliminate mechanisms that might cause instabilities. It has been shown that even a relatively small BBG can pump a large VLSI NMOS circuit to a stable predetermined voltage.