156 dB low-voltage low-power CMOS exponential function generator circuit

Abstract

An original exponential function generator is presented, the original approach allowing to extremely accurate approximate the exponential function. The circuit output dynamic range is approximately 156 dB, for a maximal approximation error equal with 1 dB. The new proposed method uses a very precise superior-order approximation function, which is developed for requiring a very ressonable hardware resources for its implementation in CMOS technology. For further improving the accuracy of the proposed function generator circuit, an additional new method using a convenient variable changing is used. The proposed computational structure is designed for low-voltage low-power operation. The circuit is supplied at 1.1 V and its maximal power consumption is approximately 5 μW. The computational structure is developed for implementing in 0.18μ TSMC CMOS process, the approximately area being 1600 μm². The SPICE simulations of the exponential function generator operation confirm the theoretical estimated results.