A New Sub-1 Volt 17ppm/°C Offset-Insensitive Resistorless Switched-capacitor Bandgap Voltage Reference

Abstract

A new PVT compensated voltage reference is presented by using switched-capacitor (S.C.) technique. In the proposed bandgap voltage reference (BGR), a p–n junction is biased with different currents during two different phases and required PTAT and CTAT voltages generated and held by two capacitors. Using a capacitive voltage divider, the PTAT voltage is weighted such that the sub-1V bandgap voltage is achievable. In order to cancel the effect of op-amp offset and to relax the design of op-amp, the offset voltage of the op-amp is sampled by a capacitor during a specified phase and inversely is added to the final bandgap voltage in next phase. The analysis of the proposed S.C. BGR is supplemented by simulation of a 0.5-V BGR with 28[Formula: see text][Formula: see text][Formula: see text]W power consumption in a standard 0.18[Formula: see text][Formula: see text][Formula: see text]m CMOS technology. Simulation results show that the average temperature coefficient of the S.C. BGR is 17[Formula: see text]ppm/∘C and it is robust against the process variations. Applying an arbitrary 100-mV op-amp offset results in a lower than 1.1[Formula: see text]mV deviation in generated reference voltage. Due to the better matching of MIM capacitors in CMOS process (rather than resistors used in conventional BGR) the proposed S.C. bandgap provides good accuracy without any post trimming. Monte–Carlo analysis shows that [Formula: see text]/[Formula: see text] of the generated reference voltage is as low as 0.7%. The sensitivity of the proposed BGR to supply variation is also less than 1%/V.

A CMOS bandgap reference based on switched capacitor with temperature compensation method

“…Ivanov et al proposed a switched capacitor BGR circuit and used it as a part of a large system on chip [21]. In addition, some other studies on switched capacitor BGR circuits have been published [22,23,24,25,26,27,28,29]. Because of the simple first order compensation method, the TC of these reference voltage is significantly large.…”

Design of a bandgap reference voltage source with low temperature coefficient and high precision

“…The bandgap reference voltage source generates a reference voltage that does not change with the power supply voltage, temperature and semiconductor process.For example, in high-precision comparators, the reference voltage source provides a comparison voltage that is not affected by PVT, and is sampled by the sampling circuit. The voltages are compared to output a stable voltage.In high-precision operational amplifiers, the bandgap reference voltage source provides accurate power supply voltage or current bias to ensure normal operation and high circuit performance [1][2][3][4][5] . Therefore, the reference voltage source is the core part of the high-precision system [6] , and its accuracy often directly determines the accuracy of the entire system.…”