A 53%-PTE and 4-Mbps Power and Data Telemetry Circuit based on Adaptive Duty-cycling BPSK Modulated Class-E Amplifier

Abstract

Implantable medical microsystems need an efficient power and data transmission link. The demand for increasing the battery life requests for higher power transfer efficiency (PTE), whereas the increasing functionality of the implantable chip demands a higher data-rate. The traditional single-pair-of-coil link based on Amplitude-Shift keying (ASK) modulated Class-E amplifier tends to have limited immunity on the interference. In addition, due to the conflict on the quality factor (Q) between the power transmission and data transmission band, high PTE and high data rates are difficult to achieve at the same time. This paper proposes a power and data transmission link based on the adaptive duty-cycling binary phase-shift keying (BPSK) modulated Class-E amplifier. The Class-E works alternatively between two modes determined by two clocks with different duty-cycles. The variation of the duty-cycle modulates the phase of the carrier through the resonant networks of the Class-E amplifier. A low-power Costas Loop is adopted to efficiently synchronize the carrier and recover the data from an inductive received signal. The whole link has been implemented and simulated in a 350-nm CMOS process. The simulation shows under date-rate of 4 Mbps, the link achieves a PTE of 53% with an energy efficiency of 600 pJ/bit.