Amplificador operacional em baixa tensão e aplicações

Abstract

Over the years, the reduction of the power supply voltage has become a main trend in the design of VLSI integrated circuits. This has been driven individually or collaboratively by technology, power management and market demands. The low voltage operation is essential in modern portable electronic systems to guarantee a smaller number of batteries on the power supply and another benefits such as reliability and consumption. Circuit designers are forced to reconsider and redesign circuits and even develop new analog circuit cells for low voltage operation. Conventional techniques to achieve a constant-gm rail-to-rail complementary N-P differential input stage require complex additional circuitry. In addition, the frequency response and common-mode rejection ratio (CMRR) are degraded. An economical but efficient design technique to overcome these problems is proposed. The proposed technique strategically overlaps the transition regions of the tail currents for the N and P-pairs to achieve constant overall transconductance with improved CMRR and frequency response. This work shows, as application of proposed operational amplifier, the design of a sample-and-hold circuit and an analog-to-digital converter. It is implemented an interesting converter technique that allows the low voltage operation and meet the needs of precision and transmission speed required by digital signal processing circuits.