A 1.8V low noise threshold voltage reference generator with temperature and process calibration

Abstract

The bandgap voltage reference is ideally independent of the power supply and the temperature drift. However, the low frequency output noise of the circuit is large due to noise contribution from the current mirrors and this is the problem in noise-sensitive applications. In this paper, a 1.8V low noise threshold voltage reference generator is proposed to generate a fairly precise reference voltage with a very low noise. A 5-bit digital calibration loop is utilized to overcome the effects of the temperature drift and process variations. Designed and simulated in a 65 nm CMOS process, the proposed threshold voltage reference generator has an output noise of 13.1nV/sqrt(Hz) at 100 KHz at 35°C, far better than traditional bandgap reference circuit. The output voltage inaccuracy is ±2.4% when the supply voltage deviates from 2.5V to 3.5V, the temperature varies from -35°C to 95°C, and over all of the process variation corners.