A SoC with 3.9mW 3Mbps UHF transmitter and 240μW MCU for capsule endoscope with bidirectional communication

An ultra-low-power system-on-a-chip (SoC) for wireless capsule endoscopes has been implemented, providing bidirectional communication between the capsule and the external data logger. The SoC is composed of a programmable UHF band transceiver with 3Mbps MSK transmitting and 64kbps OOK receiving, a 1.2V MCU with a dedicated image compressor, multiple on-chip voltage regulators, and etc. The SoC can work with a power supply down to 2.5V. The 3Mbps transmitter working at 400MHz band consumes only 3.9mW power, and the MCU draws only 200μΑ current from 1.2V supply. Fabricated in 0.18μm CMOS, the SoC occupies a die area of 13.3mm2 including the I/O pads. A capsule endoscope prototype has been developed using this SoC plus an image sensor. With this SoC, the capsule endoscope can capture 512∗512 gastrointestinal images with a frame rate of up to 3 fps.