A 0.5V 22.5ppm/°C Bandgap Voltage Reference With Leakage Current Injection for Curvature Correction
Chon-Fai Lee, U Chi-Wa, Rui P. Martins, Chi‐Seng Lam
Abstract
This brief presents a switched-capacitor network (SCN)-based bandgap voltage reference (BGR) with a leakage current injection technique for curvature correction, improving performance in terms of temperature coefficient (TC). A deep N-well NMOS transistor biased with a complementary to absolute temperature (CTAT) voltage generates a leakage current with a concave upward curvature. Subsequently, we inject this current into the SCN during the holding state for curvature correction. The injected leakage current changes the sampled CTAT voltage, achieving TC compensation without consuming too much additional power. The proposed BGR, fabricated in 65nm CMOS, occupies an active area of 0.0442 mm2. Measurements from 5 chips show that the achieved reference voltage is 432.4 mV under a 0.5 V supply. The average TC is 22.5ppm/°C over a temperature range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-40^{\circ }\text{C}$ </tex-math></inline-formula> to 120°C, significantly improving on TC while the power consumption is only 29 nW, which is comparable to previous SCN BGRs. This validates the effectiveness of the proposed leakage current injection technique for curvature correction.