Abstract
A new modified pseudo-Taylor exponential approximation is presented for realizing a current-to-current exponential function generator. The proposed approximation for exponential function generation has been implemented using translinear principle of MOSFETs operating in weak inversion region. The SPECTRE simulation tool from Cadence, with 180 nM CMOS process parameters, has been utilized for testing the workability of the CMOS implementation of the proposed approximation, which uses only \(\pm 0.5\hbox {V}\) power supply. The post-layout simulation results of the proposed CMOS exponential generator, thus, consume only \({\approx }119\,\hbox {nW}\) power and produce 51.6 dB range of linear-in-dB output with only \(\pm 0.21\,\hbox {dB}\) error while occupying an area of \(0.26\,\upmu \hbox {m}^{2}\).
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Notes
While the extension of 3 dB frequency of the proposed exponential generator can be left to future research for utilizing them in high-frequency applications of AGC/VGA such as WLAN receivers, CDMA/WCDMA receivers, GPS receivers and disk drive electronics, nevertheless, the biomedical signals (for instance, ECG or EEG), which are of low-frequency range, e.g., see [9, 11, 20], it can more effectively be processed through amplifiers of the analog front ends in biomedical electronic systems, utilizing the proposed exponential generator. Also, our proposition, with other notable superior features, suites more to many implantable miniature biodevices, namely hearing aids and pacemakers.
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An erratum to this article is available at http://dx.doi.org/10.1007/s00034-017-0509-6.
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Srivastava, P., Sharma, R.K. A Novel Exponential Approximation with \(\pm 0.21\,\hbox {dB}\) Error for Realizing an Improved CMOS Exponential Function Generator. Circuits Syst Signal Process 36, 2941–2957 (2017). https://doi.org/10.1007/s00034-016-0451-z
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DOI: https://doi.org/10.1007/s00034-016-0451-z