MBus: A 17.5 pJ/bit/chip portable interconnect bus for millimeter-scale sensor systems with 8 nW standby power

We propose an ultra-low power interconnect bus for millimeter-scale wireless sensor nodes. Using only 4 IO pads, the bus minimizes the required chip real estate, enabling ultrasmall form factors in modular sensor node designs. Low power is achieved using a “clockless” design of member nodes while aggressive power gating allows an ultra-low power standby mode with only 53 gates powered on. An integrated wakeup scheme is compatible with PMUs that have a special low power standby mode. The MBus is fully synthesizable and uses robust timing. Implemented in a 3 module system in 180nm technology, Mbus achieves 8nW of standby power and 17.5 pJ/bit/chip.