Signal Dynamic Range Expansion for Exponentiation Conversion Circuit Capable of Changing the Power Exponent to Any Value

Abstract

In order to compensate for the non-linearity of the electronic device, an exponentiation conversion circuit that can change the power exponent to any value has been proposed. The exponentiation conversion circuit multiplies the logarithmically converted input signal by the power exponent value to perform exponential conversion. As a result, we can obtain the power function characteristic of the power exponent value. This circuit is a small-scale circuit that utilizes the exponential characteristics of the MOSFET subthreshold region. In the conventional circuit, expansion of the signal dynamic range has been an issue. In this paper, it was confirmed by simulation that the signal dynamic range is expanded by optimizing the current density of MOSFETs. In addition, the linearity of the multiplication circuit was improved by introducing operational amplifier. By evaluating its prototype IC with 0.6 µm CMOS process, we confirmed the signal dynamic range was expanded from 6.90 dB to 36.7 dB in current signal input and, the power exponent value can change in the range of -0.068 to 6.2.