Resumo:
This work describes an integrated analog-to-digital interface for electric energy measurement, implemented on 0.35μm CMOS process. In this system, voltages and currents are sampled and converted to digital values for later processing. It has been used the switched capacitor technique on the sampling and conversion circuits, instead of the analogue conventional techniques, thus reducing the circuit size and achieving a higher precision.
The developed system has two input channels and can reach 10 bits of resolution at a sampling rate of 61600 words per second. Nevertheless, the system can be expanded up to 12 channels, so that at 7600 samples per second it can reach 369000 words per second. The circuit takes an area of 5.2 mm2, including pads.
The system is an improvement compared to all others since it has a built-in anti-aliasing filter and expandable acquisition channels that are simultaneously sampled. Additionally, it can be implemented on a digital process, along with the digital circuitry. Therefore, the system presents a much lower sampling cost compared to the traditional systems, since it can be manufactured on a digital process and thus the whole system can be totally integrated.
