A 1V 16.9ppm/°C 250nA Switched-Capacitor CMOS Voltage Reference

Abstract

We have developed a switched-capacitor CMOS voltage reference (SCVR). The circuit is shown in Fig. 24.3.2 and is composed of a low-power bias circuit [G. De Vita and G. iannacone, 2007], a core circuit and a switched-capacitor difference amplifier that is insensitive to op-amp offset voltage. The clock signals (phi <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> , phi <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , phi <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ') are non-overlapping to prevent leakage. The core circuit supplies V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">gs1</sub> and V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">gs2</sub> to the switched-capacitor difference amplifier on phases phi <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> and phi <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , respectively. The difference amplifier then generates an output, which has a low TC, based on the gate-source voltage difference, AVGS.