Using asynchronous circuits for communications in wireless endoscopic capsule

An ultra-low-power baseband controller in wireless endoscopic capsule is designed in asynchronous circuits based on the 2-wire protocols. The controller is adaptive to different data rates defined by an external reference data rate clock source. Other than the ultra low power property, the controller has the advantages of high bandwidth utilization efficiency and low complexity. The interfaces for asynchronous handshake and baseband channel communication are improved so that it can work with other synchronous functional parts in the application system efficiently. The asynchronous controller implementation is 2.1 K equivalent gates in standard 0.18 um CMOS process. If working at 1.8 V power supply, the IC core consumes 11.7 uW at 2 Mbps and 64.9 uW at 12 Mbps respectively. It proves to have about 60% area and 30% power consumption of the synchronous counterpart.