A Sub-1 ppm/°C CMOS Bandgap Voltage Reference With Process Tolerant Piecewise Second-Order Curvature Compensation

Abstract

This paper presents a CMOS high-precision bandgap voltage reference. To obtain low temperature coefficient (TC) regardless of process variation, piecewise second-order curvature compensation method is proposed. Curvature compensation current is generated through current subtraction and current squaring operation with two currents with different dependence on temperature. Also, several circuit techniques are adopted to achieve compensate error sources. Chopping technique is utilized to cancel 1/f noise and DC offset of the error amplifier. Trimming resistor is used to compensate process variation. The bandgap reference is designed in a 0.13µm CMOS process. Post layout simulation shows that TC of the bandgap reference is 0.64ppm/°C over a wide temperature range of -40°C to 125°C. Moreover, sub-1 ppm/°C TC is achieved irrespective of process variation after two-point temperature trimming. The bandgap reference consumes 44µA at 27°C and layout size is 0.0534mm2.