Near-Threshold 8051 Microprocessor Design With Extended Instruction Set

Wireless sensor network is one of the most important rising embedded applications in recent years.It plays a key role in many high technology fields like Internet of things and environment monitoring.Core of a wireless sensor network node is a typical microprocessor,which usually works at a low frequency fewer than 10 MHz and consumes less than 1mW dynamic power.A specific design methodology is needed for such kind of low frequency and low power digital circuits.In this article,we study and summarize energy-saving technologies in microprocessor design and divide them into three parts including circuit field,architecture field and system field.We design an energy-saving microprocessor for wireless sensor network node,where in circuit filed,a near-threshold cell library is proposed for the microprocessor,and in system field,instruction set is extended for some typical light-weighted encryption algorithms.In circuit field,we propose a near-threshold digital cell library based on SMIC 0.13 um mixed signal technology.Its design voltage is 0.6V.An 8051 microprocessor is implemented using this library and has been tapedout.Chip test results show that this microprocessor can work at 10 MHz clock frequency when given 0.6V supply voltage,and at this mode its power consumption is only 720 uW,which has fully met the need of a wireless sensor network node application.Based on the work above,this article in system field implements an Application Specific Instruction Set Processor design for two kinds of typical light-weighted encryption algorithms in wireless sensor network systems.Take Present Algorithm for example.By instruction extension and hardware acceleration,we eliminate bottleneck of this algorithm and gain a 94.6% execution time saving.So that energy consumption of this algorithm is greatly reduced by about 90%,which has a lot of benefit for subsequent design of the microprocessor.