Background: The log domain technique has been employed to enhance the dynamic range of analog circuits suitable of operation at low supply voltage. Methods: A MOS transistor operating in weak inversion region exhibits logarithmic behavior and could serve as a replacement of bipolar junction transistors which have often been employed in implementing log domain circuits. However, threshold voltage restricts the operation of MOS based log domain circuits at low supply voltage which could be eliminated by floating gate transistors (FGMOS) at the cost of low gain, low output impedance and degraded bandwidth. These limitations can be further overcame by using quasi-floating gate MOSFET (QFGMOS). Results: In this paper, we have designed an integrator based on log domain operation using QFGMOS and its performance has been compared with CMOS and FGMOS versions. Conclusion: It has been found through PSpice simulations that QFGMOS log domain integrator shows better results as compared to FGMOS based log domain integrator in terms of.
Keywords: Compressor, expander, integrator, log domain, weak inversion, threshold voltage
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