Realisation of exponential V-I converter usingcomposite NMOS transistors

Abstract

A CMOS voltage-to-current converter with exponential characteristics is presented. The Taylor's series expansion is used for realising the exponential function. In a 0.35 µm CMOS process, the HSPICE simulation results show a 15 dB linear range with a linearity error of < ±0.5 dB. The total power consumption is < 0.8 mW with ±1.5 V supply voltage. The circuit can be used in the design of a variable gain amplifier (VGA).