CMOS LOGARITHMIC CURRENT GENERATOR AND METHOD FOR GENERATING A LOGARITHMIC CURRENT

摘要

A CMOS logarithmic current generator includes current mode circuitry having a design principle based on a Taylor's series expansion that approximates an exponential function. A MOSFET circuit provides a function generator core cell having a biasing current I_b. The FETs of the circuit are matched and are biased in the weak inversion region. Additional transistors are used to convert a pair of input currents to a pair of voltages to provide an output current based upon a current mode logarithmic function. The biasing current I_b can be varied to provide a variable gain in the circuit.