Abstract
This paper describes a gain enhancement method and also a slew-rate enhancement scheme for folded-cascode amplifiers which uses positive feedback + transconductance increaser method for the sake of gain increment that gives rise to approximately 21 db of increment in the amount of the gain. An approach for increasing the slew-rate has also been employed which has increased the slew-rate of the amplifier approximately 5 times the conventional folded-cascode one as well as the triple folded-cascode one. Also the settling time and consequently the speed of the circuit is improved remarkably i.e. over 6 times the conventional folded-cascode and triple folded cascode ones. The amplifier has been designed in TSMC RF 0.18 μm and consumes 920 µw of power meanwhile provides 67 db for gain, 581 MHz for UGBW, 69° for phase margin, 793 V/µS for slew-rate and 3.2 nS for large-signal settling time as well as the gain-error of the amplifier for large-signal is approximately 0.5 %. The layout of the circuit has also been carried out in Cadence and demonstrates that the op amp occupies 41 µm × 61 µm (0.002 \(\text{mil}^{2}\)) of the die area. The post-layout-simulation of the op amp was also fulfilled and the results are displayed.
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Pourabdollah, M. A new gain-enhanced and slew-rate-enhanced folded-cascode op amp. Analog Integr Circ Sig Process 88, 43–56 (2016). https://doi.org/10.1007/s10470-016-0739-8
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DOI: https://doi.org/10.1007/s10470-016-0739-8