Adiabatic Implementation of Manchester Encoding for Passive NFC System

Energy plays an important role in NFC passive tags as they are powered by radio waves from the reader. Hence reducing the energy consumption of the tag can bring large interrogation range, increase security and maximizes the reader's battery life. The ISO 14443 standard utilizes Manchester coding for the data transmission from passive tag to the reader in the majority of the cases for NFC passive communications. This paper proposes a novel method of Manchester encoding using the adiabatic logic technique for energy minimization. The design is implemented by generating replica bits of the actual transmitted bits and then flipping the replica bits, for generating the Manchester coded bits. The proposed design was implemented using two adiabatic logic families namely; Positive Feedback Adiabatic Logic (PFAL) and Improved Efficient Charge Recovery Logic (IECRL) which are compared in terms of energy for the range of frequency variations. The energy comparison was also made including the power-clock generator designed using 2-stepwise charging circuit (SWC) with FSM controller. The simulation results presented for 180nm CMOS technology at 1.8V power supply shows that IECRL shows approximately 40% less system energy compared to PFAL family.