low-power mosfet-only subthreshold voltage reference with high psrr

This work presents a sub-nanowatt voltage reference (vr) achieving a high-power supply ripple rejection (psrr). it utilizes a self-current biasing circuit to reduce the voltage dependency of the output voltage (vref) to the power supply variations. for low-power operation, all transistors operate in the subthreshold region. the design’s performance is verified through post-layout and monte carlo simulations in a standard 180 nm cmos process. results show that the proposed bandgap achieves an output voltage of 0.150 v with a psrr of -81.5 db at v­­dd = 1v. notably, it eliminates the need for an additional startup circuit and consumes only 0.72 nw at t = 27°c with vdd = 0.5v. the proposed voltage reference exhibits a temperature coefficient (tc) of approximately 18 ppm/°c over a temperature range of -20°c to 130°c while without using a trimming circuit a reasonable (σ vref /μvref) = 2.3% is obtained. this design’s average line sensitivity (ls) is 0.072%/v (vdd = 0.5v to 1.8v). however, the psrr and ls values are temperature-dependent. at the high temperature of 130°c (worst-case), the psrr and ls degrade to approximately -80.45 db and 0.084 %/v, respectively.  the output noise at the frequency of 1 khz is obtained as 167.34 nv/ √ hz. the proposed vr occupies a small active area of 513.5 μm2.