Design of low-voltage CMOS class-AB operational amplifiers / Projeto de amplificadores operacionais CMOS classe-AB operando em baixa tensão de alimentação




This dissertation describes the process of designing rail-to-rail operational amplifiers in CMOS technology. To accomplish this, the author focused on four distinct structures. The four topologies have rail-to-rail input stage with gm-control circuit and Class-AB output stage with quiescent-current control. The specification of three configurations included the nominal power supply of ± 0.9V, minimum open-loop low-frequency gain of 60dB and unity-gain frequency of 4MHz driving an external load of 10kΩin parallel with 10pF. The fourth one is a new topology adapted to operate with transistors in weak inversion, in order to decrease the power consumption. The specification included nominal power supply of ± 0.75V and minimization of power consumption. Prototypes of the amplifiers were fabricated in 0.35µm CMOS technology and the results were in good agreements with the specifications. A printed circuit board was implemented to test the amplifiers and, additionally, was inserted a commercial amplifier, to make comparisons.


operational amplifiers amplificadores operacionais cmos integrated circuits semicondutores complementares de oxido metalico circuitos integrados complementary metal oxide semiconductors

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