Translinear circuits in subthreshold MOS
Analog Integrated Circuits and Signal Processing - Special issue: translinear circuits
A low power 48-dB/stage linear-in-dB variable gain amplifier for direct-conversion receivers
Microelectronics Journal
1.5-V CMOS exponential current generator
Analog Integrated Circuits and Signal Processing
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A new CMOS current-mode circuit to produce the exponential function, y=exp(x), is proposed. The proposed design has large input and output dynamic ranges while keeping very small linearity error. The functionality of the proposed design, confirmed using Tanner tool with 0.35@mm CMOS process technology indicates that it has superior performance compared to previously reported designs. A nearly 96dB output dynamic range is obtained with the linearity error less than +/-0.5dB over an input range -5.75@?x@?5.75. The change in the output current due to temperature variation is +/-1.27dB over 100^oC range. Application of the proposed exponential function generator in the design of an exponentially controlled variable gain amplifier is presented and its functionality is confirmed using simulation. 71 Linear-in-dB variable gain was achieved. The dB gain is controlled linearly by the control current, resulting in simple and low power structure.