Energy-minimum sub-threshold self-timed circuits using current-sensing completion detection

This study addresses the design of self-timed energy-minimum circuits, operating in the sub-VT domain and a generic implementation template using bundled-data circuitry and current sensing completion detection (CSCD). Furthermore, a fully decoupled latch controller was developed, which integrates with the current-sensing circuitry.

Different configurations that utilise the proposed latch controller are highlighted. A contemporary synchronous electronic design automation tools-based design flow, which transforms a synchronous design into a corresponding self-timed circuit, is outlined. Different use cases of the CSCD system are examined.

The design flow and the current-sensing technique are validated by the implementation of a self-timed version of a wavelet-based event detector for cardiac pacemaker applications in a standard 65 nm CMOS process. The chip was fabricated and verified to operate down to 250 mV. Spice simulations indicate a gain of 52.58% in throughput because of asynchronous operation.

By trading the throughput improvement, energy dissipation is reduced by 16.8% at the energy-minimum supply voltage.