A 0.9-V 33.7-ppm/°C 85-nW Sub-Bandgap Voltage Reference Consisting of Subthreshold MOSFETs and Single BJT

A low temperature coefficient (TC) and high power supply ripple rejection (PSRR) CMOS sub-bandgap voltage reference (sub-BGR) circuit using subthreshold MOS transistors and a single BJT is presented in this brief. The proposed sub-BGR consists of a novel complementary-to-absolute-temperature (CTAT) voltage generator based on a scaled emitter-base voltage of a BJT, and an improved proportional-to-absolute-temperature (PTAT) voltage generator based on stacking of $\Delta V_{\mathbf {GS}}$ of sub- $V_{\mathbf {TH}}$ MOSFETs. As the CTAT circuit achieves a reduced absolute value of the negative TC, the PTAT circuit achieves reduced power consumption without consuming a large chip area. The proposed sub-BGR circuit is implemented in a standard 0.18- $\mu \text{m}$ CMOS process. Measured results show that the sub-BGR circuit can run with a supply voltage down to 0.9 V while the power consumption is only 85 nW. An average TC of 33.7 ppm/°C and a PSRR of better than −40 dB over the full frequency range are achieved.