A novel CMOS exponential voltage generator based on differential pair's transfer characteristic

A novel voltage-mode CMOS exponential function circuit for VGAs is developed in this paper. The core circuit is based on a traditional differential pair and a newly-designed three-transistor differential pair. The generated exponential voltage starts from, but does not cross, the 0 V point. On a 0.25 /spl mu/m CMOS process, the simulation results with 3.3 V supply voltage show that the dB-linear function in the entire voltage control range achieves over 50 dB range with an error less than 1 dB.