Design of a sub 1-V MOSFET based voltage reference circuit operating in subthreshold region

This paper presents the design and implementation of a precision voltage reference circuit using MOSFETs operating in the subthreshold region. It also shows the effect of technology scaling in designing voltage reference circuits. The circuit has been design and simulated in 28nm and 90nm CMOS technologies. For the 28nm technology, the circuit provides a reference voltage of 225 mV with a line sensitivity of 0.5%. The minimum and the maximum supply voltages are 0.9V and 3.25V, respectively. An average temperature coefficient of 138.5 ppm/°C, through a temperature range of (-20-150) °C, is achieved. Moreover, the power supply rejection ratio is -62dB at 50Hz and -49dB at 100 KHz. For the 90nm technology, a reference voltage of 115mV is obtained with a line sensitivity of 3.1% and a supply voltage as low as 0.25V. The temperature coefficient is 518 ppm/ °C, through a temperature range of (-20-80) °C, whereas the power supply rejection ratio is -31dB at 50Hz and -49dB at 100 KHz. The design is verified using Synopsys Custom Designer and HSPICE CAD tools.