BARRETO, A. C.; BARRETO, Andrea Costa.
Résumé:
This work presents the conception of an analog signal conditioning circuit to be integrated into an ASIC (Application Specific Integrated Circuit), which meets the requirements of the digital to analog converter embedded in a microcontroller used in data acquisition systems. The conditioning circuit architecture here presented is composed by a differential amplifier, a buffer circuit and a reference voltage generator.
The reference voltage is externally provided to the analog to digital converter. Two areas of application are presented as targets: industrial and medical, but the chip to be developed can be used in other applications. The design of transistor-level blocks that make up the circuit is accomplished. The differential amplifier, the major part of the
signal conditioning circuit, is responsible for amplifying and providing a DC level to the signal being measured by the data acquisition system, adjusting it to the range between 0 V and a voltage value generated by a reference circuit. The buffer circuit makes a copy of the differential amplifier output voltage at its own low impedance output, providing the signal to be read by the analog to digital converter. ON Semiconductor
CMOS 0.5 m technology is used for the design. The simulation results for the internal functional blocks of the integrated circuit are shown. In order to test the performance of the complete conditioning circuit, we present the results for two input signals with amplitudes in the extremes of application considered in this work: a power grid signal
and an electrocardiogram (ECG) signal. After the simulations, the layout is presented with appropriate verification of this circuit within the limits imposed by the design kit technology used. With the results of this dissertation, this design will be fabricated and subsequently characterized.
