Electronics in Automation

Analog electronics for sensors and embedded systems.

Operational amplifiers and circuits for analog signal conditioning and processing: voltage comparator, voltage follower, inverting and non-inverting voltage amplifier, adder, subtractor, instrumentation amplifier, adjustment of voltage ranges, current-to-voltage converter, peak detector, Schmitt trigger, voltage references. D/A and A/D converters: types and their use in circuits. Resistors, capacitors, built-in and parasitic RC and CR combinations, diodes.

All circuits are illustrated with examples. Analyses and descriptions are highly non-idealized, and they highlight the real characteristics and their parasitic influences on the functioning of the circuits. Non-idealities are analyzed and illustrated with datasheets from manufacturers. Demonstrated are differences between the selected models of operational amplifiers. Described is capturing of signals from voltage, current and resistive sensors with practical examples.

Non-idealities, which tend to hamper precision sensor systems, are thoroughly analyzed: offset voltage, input bias current, input offset current, input and output internal resistances, impact of non-infinite amplification, frequency limit, common-mode rejection, unstable power supply, slew rate, impact of load capacitance, drift, noise, temperature dependence. Outlined are compensations of offset voltage and input bias current, presented are methods for increasing of common-mode rejection ratio. Explained is the use of two operational amplifiers in the loop and correction of frequency characteristics. The most thoroughly discussed non-idealities of AD and DA converters are zero and full-range offset, gain error, integral and differential non-linearity. Demonstrated are measurements of signals’ spectra and observations of distortion.

Analog characteristics of digital circuits with an emphasis on the use in conjunction with embedded systems: output resistance, input impedance, power consumption in conjunction with switching frequency, the influence of capacitive loads, types of digital outputs (totem pole, open drain). Oscillators for microprocessor systems. Analog switches and multiplexers together with their non-idealities.

Practical aspects of circuit realization: non-ideal ground and power lines, the use of blocking capacitors, the concept and use of connections FORCE SENSE and REF, DC and AC coupling, basics of transmission lines.

Mastering the concepts and operation of analog circuits for realization of sensor and embedded systems. Treatment is highly non-idealized and with highlight on deviations from the idealized characteristics and the associated problems that occur in practice.

 Lectures give students theoretical knowledge. Laboratory courses are tightly coupled with lectures, and give true hands-on experience of the lectured topics. Demonstrated is the working of discussed circuits, their non-idealities and methods for their handling.