Low power receiver for magnetic digestive motility tracking pill

A CMOS integrated RF receiver of a glass pill for tracking motility in the gastrointestinal (GI) tract is presented. The receiver detects a 125 kHz downlink synchronization signal that is sent from an external base station, which is used to trigger the transmission of the 3-axis pill position and also to change the tuning parameters of the receiver system. The incoming downlink RF signal also includes the tuning parameters for the 10-bit resolution adjustable internal ring-oscillator, which generates a 4 MHz clock for providing the 3-axis pill position through the 125 kHz transmitter. The receiver, which is fabricated in UMC 0.18 μm CMOS process is measured using the housing of the glass pill. Experiments show that a maximum operation distance of 80 cm between the base station and the glass pill is achieved. The total power consumption of the integrated solution provides 4.6 times reduction compared to the previous generation tracking pill.