A 0.5-ppm/°C Voltage Reference With Sub-Ranging On-Chip Self-Heating and Second-Order Compensation in 65-nm CMOS

This article presents a voltage reference with ultralow temperature coefficient (TC), which is suitable for high-precision industrial applications. Using a shunt resistor in the current-mode bandgap reference (BGR) achieves a complementary-nonlinear PTAT current for second-order temperature compensation ranging from $10~{^{\circ } }$ C to $85~{^{\circ } }$ C. Additionally, a temperature-locked loop (TLL) is implemented to regulate on-chip self-heating, maintaining a stable die temperature at $10~{^{\circ } }$ C across the ambient range from ${-} 40~{^{\circ } }$ C to $10~{^{\circ } }$ C, thereby significantly improving the overall TC. The proposed voltage references have been designed and fabricated using a standard 65-nm CMOS technology. The proposed on-chip self-heating BGR with second-order compensation achieves an average TC of 0.50 ppm/°C with a standard deviation of 0.12 ppm/°C after one-point trimming from ${-} 40~{^{\circ } }$ C to $85~{^{\circ } }$ C. It consumes $23.3~{\mu }$ A at $27~{^{\circ } }$ C and occupies 0.12 mm².