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Linearity improvement of source degenerated transconductance amplifiers

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Abstract

Mobility degradation is predominant in submicron CMOS technology. The effect of this mobility reduction in a linear operational transconductance amplifier (OTA) with signal attenuation and source degeneration is examined in this study. Theoretical analysis shows that the cubic non-linearity in the attenuator helps to improve the linearity of the source degenerated transconductor by partial cancellation of the harmonic distortion component. Such a linear transconductor and a third order low pass filter based on this linear OTA are fabricated in UMC 180 nm CMOS process technology. Experimental results show that third order intermodulation distortion of the linear OTA is less than −60 dB for 500 mVpp differential input signal while for 2 % transconductance variation the linear range is about 1.2 Vpp. The linear transconductor consumes only 0.45 mW of power with 1.8 V supply.

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Acknowledgements

Authors would like to acknowledge the financial support from Department of Information Technology (DIT), Government of India for fabrication of the chip.

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  1. Department of Electrical Engineering, Indian Institute of Technology, Kharagpur, India

    Sougata Kumar Kar & Siddhartha Sen

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  1. Sougata Kumar Kar
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  2. Siddhartha Sen
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Correspondence to Sougata Kumar Kar.

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Kar, S.K., Sen, S. Linearity improvement of source degenerated transconductance amplifiers. Analog Integr Circ Sig Process 74, 399–407 (2013). https://doi.org/10.1007/s10470-012-9948-y

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