Ing Ind - Inf (Mag.)(ord. 270) - MI (474) TELECOMMUNICATION ENGINEERING - INGEGNERIA DELLE TELECOMUNICAZIONI
096032 - ELECTRONICS
Ing Ind - Inf (Mag.)(ord. 270) - MI (486) ENGINEERING PHYSICS - INGEGNERIA FISICA
096032 - ELECTRONICS
This is a course devoted to mastering techniques for signal recovery from noise in modern data acquisition systems. In a blend of electronics, physics and signal processing we will cover amplifiers, sensors and signal conditioning techniques, keeping an eye on both their physical/theoretical working principles and their real characteristics. Students are expected to gain skills on the design of relatively simple data acquisition systems and on the selection criteria of their various components.
Risultati di apprendimento attesi
Expected learning outcome
On completion of this course, students will:
· understand the principles and operation of operational amplifiers (OAs) and their limitations;
· have a sound knowledge of linear circuits made with OAs and of the techniques used to analyze the circuits and assess their performance;
· know the problems related to resistive sensors and their connection in a Wheatstone bridge configuration, either local or remote;
· understand noise in circuits and acquisition systems, its sources and properties;
· understand the principles of signal recovery from noise and know the different techniques.
1) knowledge and understanding
Specific examples and case studies will be provided to make students able to:
· design simple linear circuits employing OAs;
· design a proper sensor connection and a suitable amplifier accounting for non-idealities in the signal path;
· choose the correct signal recovery technique based on the signal and noise characteristics.
2) applying knowledge and understanding
Operation amplifiers (OAs): voltage and current amplifiers, input and output impedances. Negative feedback and application to amplifier design. Elementary linear stages and impedances. Real OAs: DC and AC parameters. Instrumentation amplifiers and CMRR. Frequency response of OA circuits, stability of the feedback loop and frequency compensation. Capacitive loading of OA stages.
Sensors: signal readout from resistive sensors: single-ended and differential signals, Wheatstone bridge and balancing, 2-, 3- and 4-wire connections. Temperature compensation. Sensor generalities and parameters: resolution, linearity, sensitivity, offset, drift. Example of resistive sensors: strain gauges. Temperature sensors: RTD and thermistors, electrical and thermal circuits. Thermoelectric effects and thermocouples.
Noise: signals and noise in time and frequency domains. Autocorrelation and power spectral density. Thermal noise in resistors, Nyquist derivation. Shot noise and Poisson random process model. Flicker noise. Noise in linear circuits and OAs, equivalent input noise. Noise factor and figure, signal-to-noise ratio (S/N). Feedback and noise.
Signal recovery: the case of white noise: low-pass and time-variant filters. Weighting functions. Gated integrators and improvement of S/N. Boxcar averagers and ratemeters. Discrete-time filters and their representation in time and frequency domains. Comparison between continuous- and discrete-time filters. Optimum filtering. The case of low-frequency noise: high-pass filters and effect on pulsed signals. Baseline restorers. Amplitude modulation and synchronous detection. Lock-in amplifiers, analog and digital LIAs.
There is no official prerequisite for this course. However, an understanding of linear circuit theory is highly recommended and will be assumed. Some familiarity with symbolic impedances and Bode plots is also useful. Please, contact me if you have never been exposed to these topics before.
Modalità di valutazione
Students are required to pass a written exam, consisting of two problems with four questions each. Such parts refer to the main blocks of the course and are meant for the students to show
For the first part:
- An understanding of the operating principles of realistic circuits built using operational amplifiers;
- The capability to analyze such circuits and evaluate their performance;
- Some design capabilities, when modifications of the proposed scheme is asked in order to reach a specified goal;
- The capability to evaluate the circuits from the viewpoint of noise;
and for the second one:
- An understanding of the basic principles of signal recovery;
- The capability to evaluate the signal and noise performance in a particular signal acquisition scheme;
- Some design capabilities, when they need to propose what signal recovery scheme is most suitable to solve a specific problems.
Texts and solutions of previous examinations are available on the instructor’s website.