Low-Power Exponential V-I Converter Using Composite PMOS Transistors

A low-power exponential voltage-to-current (V-I) converter is presented. The dB-linear function behavior based on the concept of Taylor series expansion is achieved using the composite PMOS transistors. In a tsmc 0.18μm process, the HSPICE simulation result shows a 15dB linear range with the linearity error less than ±0.5dB. The power consumption of the proposed exponential V-I converter is 24gW from a 1.5V power supply. The presented circuit occupies only 0.014×0.014mm2 layout area after trimming.