Amplificador operacional de transcondutância insensível à variação de temperatura e baixa distorção harmônica para aplicação em filtros contínuos no tempo

Abstract

[EN] In order to process digital signals, analog-to-digital converters are essential for data acquisition systems. In any analog-to-digital converter (ADC), the band limiting filter, anti-aliasing, allows sampling in accordance with the Nyquist-Shannon theorem. These filters are continuous over time, and their implementations in CMOS (Complementary Metal-Oxide-Semiconductor) technologies are usually made by operational transconductance amplifiers (OTA) and capacitors: that defines the topology known as 𝐺𝑚 − 𝐶 filter. These filters are also used for applications in sigma-delta ADC, which provide a large number of significant bits. In smart vehicles, sensors are used to monitor external ambient variables, which are shared with other system devices in order to provide the vehicle awareness of its environment. It is important that the ADC must be insensitive to temperature variations to guarantee system performance and reliability. In this work, a fully-differential OTA was developed, with low temperature sensitivity in the range of − 50 to 175 °C. Another important aspect to be observed is that the total harmonic distortion (THD) must be low. In this work, the developed OTA allowed the design of a low pass filter whose performance parameters present low temperature sensitivity and low THD.