CMOS exponential current-to-voltage circuit based on newly proposed approximation method

This paper proposed a low-voltage and low-power current-to-voltage converter with controllable transconductance. The proposed circuit uses a newly proposed approximation function to increase the dB-linear output range. In a 0.25 μm CMOS process, the simulations show a 58 dB output voltage range and a 46 dB with the linearity error less than ±0.5 dB. The average power dissipation is less than 0.8 mW at 1.5 V supply voltage. The proposed circuit can be used for the design of an extremely low-voltage and low-power variable gain amplifier (VGA) and automatic gain control (AGC).