Minimum energy point of sub-threshold operated pass-transistor circuits

In systems such as energy-harvester powered wireless sensors, energy consumption is the most important design concern. Thus the initial design point is moved from minimum delay to minimum energy point, found in the sub-threshold operation region. An overview of minimum energy approach to circuit design is given in this paper. In order to lower energy consumption, pass-transistor logic circuits are operated in the sub-threshold region. Benefits of combining these technologies are discussed and investigated through Pspice simulations. The results show that it is possible to further lower energy consumption by slowing down the transitions between the input signal logic levels.