A low-energy low-voltage asynchronous 8051 microcontroller core

In this paper, we propose a low-energy, low-voltage (1.1 V) 8051 microcontroller core using asynchronous logic based on Austria Micro Systems (AMS) 0.35 mum technology for hearing instrument (hearing aid) applications. The A8051 microcontroller features precise functionality at voltages even down to 0.9 V. We propose several novel techniques to achieve low energy dissipation. Firstly, to minimize the activity of the system, we divide the microcontroller into a 2-stage pipeline. Both stages of the pipeline operate almost independent of each other, thus minimizing the chances of pipeline stalls. Secondly, to be energy efficient, we eliminate predictive algorithms; fetching every instruction and data only if necessary. Thirdly, identifying regular opcode patterns and using partial decodings to achieve a 30% reduction in energy dissipation. Lastly, we propose a unique indirect data memory fetching method where an indirect data can be fetched in one memory request cycle. Transistor-level simulations show that our proposed A8051 microcontroller operates at 0.6 MIPS and dissipates 130 pJ/instruction @ 1.1V