Design of area efficient and low power bandgap voltage reference using sub-threshold MOS transistors

Voltage references are very essential components of analog VLSI circuits. A reference source is expected to remain constant against supply voltage, temperature and process parameter variations. The forward voltage drop across junction diode exhibits a negative temperature dependence of about 2mV/°C, which is compensated by a suitably scaled proportional to absolute temperature (PTAT) component to obtain the bandgap voltage reference. The conventional bandgap voltage reference constituting of bipolar transistors and opamp will consume more power and area. In order to overcome this drawback, we propose a novel design of low power bandgap voltage reference that substitutes sub-threshold MOS transistors in place of bipolar transistors and a regenerative bias circuit in place of opamp. The circuit works on a supply of 1V (±10%) and within a temperature range of -40°C to 125°C. The circuit is designed to give a constant voltage of 546.3mV with a temperature coefficient of 14.4ppm/°C. The proposed circuit occupies an area of 0.0094mm² which is very less as compared to commonly used architectures. The designed architecture is tested across all the process corners [SS, FF, TT, SNFP and FNSP] in 180nm technology using CADENCE tool (UMC180).