Computer-Aided Design Techniques for Low Power Sequential Logic Circuits

This text presents a methodology for low power design. The authors first present a survey of techniques for estimating the average power dissipation of a logic circuit. At the logic level, power dissipation is directly related to average switching activity. A symbolic simulation method that accurately computes the average switching activity in logic circuits is then described. This method is extended to handle sequential logic circuits by modelling correlation in time and by calculating the probabilities of present state lines. The author then presents a survey of methods to optimize logic circuits for low power dissipation which target reduced switching activity. A method to retime a sequential logic circuit where registers are repositioned such that the overall glitching in the circuit is minimized is also described. The author then detail a powerful optimization method that is based on selectively precomputing the output logic values of a circuit one clock cycle before they are required, and using the precomputed value to reduce internal switching activity in the succeeding clock cycle.Presented next is a survey of methods that reduce switching activity in circuits described at the register-transfer and behavioral levels. Also described is a scheduling algorithm that reduces power dissipation by maximising the inactivity period of the modules in a given circuit.