Abstract
This article presents a controller IC for smart contact lens (SCL). For wireless telemetry, we propose a trans- mitter supporting dual-mode operations with a single external loop antenna. In the wireless-powered backscattering load-shift keying (LSK) mode, the transmitter is configured to use the antenna as an L for magnetic resonance coupling. The trans- mitter switches its configuration to be an active LC oscillator circuit in the RF-radiated transmission mode. To suppress the average power consumption, a 0.2% duty cycling is applied with a controlled timing schedule while minimizing static power consumption in the sleep mode. To reduce the effect of instanta- neous discharging, the period of data transmission is shortened by transmitting data with a higher rate. The designed IC is fabricated using 0.18- µmC M O S .F o rin vitro verifications in both modes, an SCL is implemented by integrating the IC, a glucose sensor, a thin-film battery, a loop antenna, and a supply- regulating capacitor. The IC achieves a power consumption of 143 nW with an input dynamic range of 89 dB.