This paper presents a novel bimodal, low-power, mm-scale transceiver for insertable smart pills. The proposed PA-less, 915 MHz uplink transmitter (TX) incorporates an 1.21.2 mm2 on-chip, non-resonated antenna as part of a current-starved ring oscillator (RO) and directly transmits data by turning the RO on/off. This RO-based uplink TX is implemented in 180 nm CMOS along with a power management unit, which generates all internal reference voltages and supplies from a single battery. The uplink TX achieves a data rate of 33 Mb/s and consumes 210 μW, resulting in an energy efficiency of 6.4 pJ/bit. The orientation-insensitive magnetic field-based downlink receiver (RX) is implemented with an external 3-D magnetic sensor, achieves 0.02 kb/s of data rate limited by our measurement setup, and consumes 270 μW. Wireless measurements in saline over 150 cm and prototype of the 3.213.62.3 mm3 insertable pill are presented.
Keywords: Gastrointestinal (GI) tract; RF transmitter; ingestible devices; insertable pills; low-power transceiver; magnetic field-based receiver; on-chip antenna; on-off keying.