Design of highly stable bandgap reference circuit for RF power harvester module of a 13.56 MHz smart card tag IC

Abstract

Design of a temperature compensated and a highly stable bandgap voltage reference (BGR) circuit is presented in this paper. The design is used for power harvester in a 13.56 MHz smart card tag IC. In order to provide a high-power supply rejection ratio (PSRR) and wide range input supply, the bandgap reference circuit is enhanced by a pre-regulator circuit. The pre-regulator circuit is designed using differential amplifier to form a Low-dropout (LDO) regulator with a feedback to BGR core circuit. The pre-regulator circuit mainly improves the stability of output voltage when the input voltage changes. In bandgap core circuit, the reference voltage is obtained by compensating the negative temperature coefficient (CTAT) with a positive temperature coefficient (PTAT). Therefore, the output voltage can be kept stable when the temperature changes. Additionally, the start-up circuit is designed to overcome zero current condition in BGR circuit during the power starts on and this circuit turns off after the whole circuit reaches the desired operating point. This paper provides both the schematic and layout design implemented in 180nm CMOS technology. From the simulation result, the output voltage has a temperature coefficient of −0.26 mV/°C with temperature range from −50 °C to 125 °C and PSRR of −116 dB at DC with input voltage supply range of 1.8–6 V. The output voltage reference is stable around 1.143 V at the operating point region.