dB-linear V-I converter using composite NMOS transistor

A new CMOS exponential V-I converter (EVIC), based on Taylor's concept and using NMOS transistor, is presented in this paper. The proposed-modified Taylor series expansion is used to extend the dB-linear output current range. In a 0.25 /spl mu/m CMOS process, the simulations show more than 22 dB output current range and 17 dB linear range with the linearity error less than /spl plusmn/0.5 dB. The power dissipation is less than 0.3 mW with /spl plusmn/1.5 V supply voltage. The proposed EVIC can be used for the design of an extremely low-voltage and low-power variable gain amplifier (VGA) and automatic gain control (AGC).