A Two-step Linear-Exponential Incremental ADC with Slope Extended Counting

Abstract

Two-step linear-exponential architectures can be applied to incremental ADCs (IADC) to achieve high resolution. In the first step, the ADC works as a normal first-order IADC while, in the second step, the exponential integrator is used to implement extended counting. There exist two architectures for the implementation of the exponential step, where the only difference depends on whether the input signal is connected or disconnected. By conducting a comparative analysis on such two slightly different linear-exponential architectures, we propose to combine the exponential and slope techniques to further boost the resolution without degrading its original thermal-noise suppression ability and DWA effectiveness. Mathematical analysis and simulation results are presented to confirm the principle of the proposed IADC.