Input characteristics of a chopped multi-path current feedback instrumentation amplifier

This paper presents simulations and measurements of the input impedance, input bias and offset current of a chopped multi-path current feedback instrumentation amplifier. In precision applications, these parameters, together with a finite impedance source can lead to significant measurement errors. In this paper, design strategies to minimize these errors are provided. At a chopping frequency of 30 kHz, the proposed amplifier has an input impedance of 6 MΩ, with bias and offset currents of 102pA and 43pA, respectively. In addition, it achieves low noise (21nV/√Hz), low (2 μV) input-referred offset, high common-mode rejection ratio (134dB) and high power supply rejection ratio (120dB).