An improved CMOS voltage bandgap reference circuit

Abstract

Bandgap Reference (BGR) circuit plays a vital role in analog and digital circuit design. BGRs provide temperature-insensitive reference voltages subject to silicon bandgap (1.2 eV). Implementation of BGR circuit zero temperature coefficient (TC) by using P–N diodes and making temperature independent by combining proportional to absolute temperature (PTAT) and complimentary to absolute temperature (CTAT) voltages. PTAT generation and start-up circuits are the two basic elements of BGR to anticipate in nano-watt applications. Start-up circuit requires for PTAT to avoid undesirable zero bias condition. The start-up circuit consists a potential divider with resistors between supply rails. The DC current flows through a resistance path which is larger than leakage current to make the start-up circuit in stable operation. This work proposes bandgap reference circuit with PTAT generation by avoiding the need of start-up circuit and assumption made for PTAT as strong forward bias. This simulation is carried with cadence environment in UMC 180 nm technology. This proposed work results show low temperature coefficient, high accuracy in output voltage, and temperature is varied from −20 to 200 ppm/°C with 1.8 V supply voltage.