Energy Recycling Telemetry IC With Simultaneous 11.5 mW Power and 6.78 Mb/s Backward Data Delivery Over a Single 13.56 MHz Inductive Link

Abstract

We present a telemetry IC with a new data modulation scheme for efficient simultaneous transfer of power and backward data over a single inductive link. Data-driven synchronized single-cycle shorting of the secondary LC tank conserves reactive energy while inducing an instantaneous voltage change on the primary side. Contrary to conventional load shift keying modulation, the recovery time of the secondary LC oscillation after shorting improves asymptotically with increasing quality factor of the secondary LC tank. Since quality factor does not reduce the data rate, the LC tank can be simultaneously optimized for power and data telemetry, obviating the conventional tradeoff between power transfer efficiency and data rate. Cyclic ON-OFF keying time-encoded symbol data mapping of the shorting cycle allows transmission of two data bits per four carrier cycles while supporting simultaneous power delivery during at least six nonshorting out of eight half cycles. All timing control signals for rectification and data transmission are generated from a low-power clock recovery comparator and a phased-locked loop. The 0.92 mm(2) 65 nm CMOS IC delivers up to 11.5 mW power to the load and simultaneously transmits 6.78 Mb/s data while dissipating 64 mu W power. A bit error rate of <= 9.9 x 10(-8) was measured over a single 1 cm 13.56 MHz inductive link at a data rate of 6.78 Mb/s with a 10 mW load power.