A Novel High-Resolution Interface Circuit for Resistance Measurement

Resistive sensors have been widely used due to their advantages in high linearity and stable performance. The measurement of their resistance is a key issue in the sensor readout circuit design. In this article, a novel resistance measurement interface circuit is proposed and fabricated in standard 180-nm CMOS technology. The presented circuit consists of a bandgap reference, an autozero offset-stabilized amplifier, a damped-switch capacitor (SC)-based self-adapted variable gain amplifier (VGA), and a 12-bit successive approximation register (SAR) analog-to-digital converter (ADC). The reference adopts a novel second-order base-current compensation circuit to generate stable supply for the circuit. Autozero offset-stabilized amplifier reduces the effect of the input offset voltage and the self-adapted VGA increases the dynamic input range of resistance the circuit as well as reduces the offset of two-stage amplifier. The experimental results indicate that the circuit has an input range of $50~\Omega $ –1.8 k $\Omega $ . The maximum of relative error in the test is 1.82% at about $100~\Omega $ and 0.64% at about $1000~\Omega $ . The power consumption of the circuit is $221~\mu $ W and the area of the core of the whole chip is 0.5192 mm2.