Design of a range-segmented CMOS current-mode exponential circuit

Authors : Chihjen CHENG, Kuojen LIN, Jwue CHEN

Pages : 2475-2487

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Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :A CMOS current-mode exponential circuit is designed by plugging candidate circuits into a Taylor`s approximation circuit to make a multiple-segment circuit. The selection of candidate circuits is dependent on a large linearity range in each segment. The proposed range-segmented circuit is different from all segments constructed only by quadratic circuits or only by linear circuits. The proposed circuit was simulated using UMC 0.18~$\mu$m CMOS technology. The output linearity of the circuit is 56.7~dB for gain error less than 0.5~dB, and the --3~dB bandwidth of the circuit is between 69 and 150~MHz for input range from --63 to 198~$\mu$A.
Keywords : Exponential circuit, multiple segments circuit, current mode circuit, quadratic circuit