Linearity improvement of source degenerated transconductance amplifiers
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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.
KeywordsAttenuation Factor Differential Pair Input Transistor Operational Transconductance Amplifier Distortion Component
Authors would like to acknowledge the financial support from Department of Information Technology (DIT), Government of India for fabrication of the chip.
- 3.Tsividis Y., Czarnul Z., Fang S. C. (1986). MOS transconductors and integrators with high linearity. Electronic Letters, 22, (5).Google Scholar
- 8.El mourabit, A., Sbaa, M. H., Alaoui-Ismaili, Z., Lahjomri, F. (2007). “A CMOS transconductor with high linear range,” IEEE International Conference on Electronics, Circuits and Systems,ICECS’07, pp. 1131–1134.Google Scholar
- 10.Lujan-Martinez, C., Carvajal, R. G., Torralba, A., Ramirez-Angulo, J. (2008). A −72 dB @ 2 MHz IM3 CMOS tunable pseudo-differential transconductor. IEEE International Symposium on Circuits and Systems, ISCAS’08, 73–76.Google Scholar
- 14.Kar S., Sen S. (2011). A highly linear CMOS transconductance amplifier in 180 nm process technology. Analog Integrated Circuits and Signal Processing, doi: 10.1007/s10470-011-9796-1.
- 15.Sanchez-Sinencio, E. (2000). Operational transconductance amplifiers (OTAs): A tutorial. Analog and Mixed Signal Center, TAMU.Google Scholar
- 16.Razavi, B. (2005). Design of analog CMOS integrated circuits. Tata McGraw-Hill, New Delhi.Google Scholar
- 18.Tsividis, Y. (1987). Operation and Modelling of the MOS Transistor. New York: McGraw-Hill Book Company.Google Scholar