PHY3128 Electronics for Measurement Systems

2007-2008

Code: PHY3128
Title: Electronics for Measurement Systems
Instructors: Dr C.D.H. Williams
CATS credits: 10
ECTS credits: 5
Availability: unrestricted
Level: 3
Pre-requisites: Practical Electronics II (PHY2003)
Co-requisites: N/A
Background Assumed: N/A
Duration: Semester II
Directed Study Time: 22 lectures
Private Study Time: 78 hours
Assessment Tasks Time: -
Observation report: 2001/02 CPW

Aims

Physicists often need to build measurement and control systems, and there are many commercially available integrated circuits and modules which simplify the task. However, to use these successfully one needs not only to understand the detailed specifications of an individual device, but also to be aware of the subtle problems that can arise (for example as a result of non-ideal behaviour, or feedback) within the integrated system. This module is particularly appropriate for MPhys students undertaking experimental projects, and others with a particular interest in electronics.

Intended Learning Outcomes

Students will be able to:

• describe and apply models of non-ideal op-amp behaviour;
• analyse circuits involving op-amps;
• quantify noise and signals in systems;
• solve problems involving transmission lines;
• explain how a range of phenomena can be exploited to measure basic physical quantities;
• identify causes and cures for electrical interference;
• describe electrical hazards and explain the protective purpose and function of insulation and grounding systems;
• recognise the qualitative effect of feedback in AC systems and have a practical knowledge of PID control;
• relate the behaviour of a system to features of its gain/phase response;
• describe the operation of a lock-in amplifier;
• discuss various types of A-D conversion circuits and coding schemes;
• judge what combination of analog or digital hardware, or software, would be an appropriate way to implement different parts of a new measurement system.

Transferable Skills

As well as developing some widely applicable knowledge of electronics and systems, students will discover that even apparently simple systems can exhibit behaviour that is unexpected, and that in-house development is a risky business.

Learning and Teaching Methods

Lectures, WWW resources and self-study documents, and problems classes.

Assignments

Solve self-study problems in preparation for class discussion.

Assessment

One 90-minute examination (100%).

Syllabus Plan and Content

1. Introduction
   1. Build it or buy it?
2. Transmission of Signals
   1. Transmission lines: time- and frequency-domain behaviour; n-mode systems.
   2. Parallel and serial data exchange, handshaking, interrupts. Computer Interfaces for Instrumentation Systems: RS-232, IEEE 488 (GP-IB), etc.. Role of PC's and micro-controllers.
   3. Case study: Ethernet
3. Introduction to Sensors
   1. Resistive - Temperature; Capacitive - Pressure; Inductive - Displacement; Electromagnetic - Flow; Thermoelectric - Heat Flux; Piezo-electric - Force; Photoelectric - Light Flux
4. Analogue Electronics
   1. Revision of the ideal operational-amplifier model
   2. Non-ideal operational-amplifier model, including: input bias and offsets, gain-bandwidth product, input and output impedance, differential and common-mode gains, and noise sources
5. Feedback and stability
   1. Transfer functions; Closed- and open-loop gain/phase; phase and gain margins; Bode diagrams
   2. Case study: Proportional-integral-derivative (PID) temperature control
6. Detecting Small Signals
   1. Noise sources
   2. DC measurements
   3. Signal and noise transfer functions, definition of the responsivity, sensitivity and resolution of a measurement system
   4. Phase-sensitive detection
   5. Case study: Matched Photodiode Detectors for X-ray CT
7. Signal Integrity and Electromagnetic Compatibility
   1. Interference, connections and grounding; how to avoid, recognise and cure problems
   2. Case study: Electrocardiogram (ECG) Measurements
8. Analogue signal processing
   1. Filters
   2. Negative impedance conversion - gyrators
9. Electrical safety:
   1. Physiological effects of electric current, Class I and Class II insulation, Residual Current Devices
10. Nonlinear Circuits
    1. Modulation and Demodulation
    2. Phase-Locked Loops
    3. Case study: Voltage-to-Frequency and Frequency-to-Voltage conversion
    4. Analysis by linearisation about an operating point
    5. Logarithmic amplifiers
    6. Non-idealities in passive components
11. Digital Signal Processing
    1. Analogue-to-digital and digital-to-analogue conversion, accuracy and sampling considerations
    2. Codes and conversion circuits
    3. Fourier transforms and their applications
    4. Digital filters
12. Extreme Techniques
    1. Resistance thermometry at low temperatures
    2. Coaxial AC-Bridge
    3. T-coils
    4. SQUIDS

Core Text

Not applicable

Supplementary Text(s)

Bentley J.P. (1988), Principles of Measurement Systems (2^nd edition), Longmans, ISBN 0-582-30543-8 (UL: 530.8 BEN)
Clayton G. and Winter S. (2003), Operational Amplifiers (5^th edition), Newnes, ISBN 0-7506-5914-9 (UL: 621.375 CLA)
Horowitz P. and Hill W. , The Art of Electronics (2^nd edition), Cambridge (UL: 621.381 HOR/X)
Peatman J.B. (1998), Design with PIC Microcontrollers, Prentice Hall, ISBN 0-13-759259-0 (UL: 629.895 PEA)
Webster J.G., Clark Jr J.W. and Neuman M.R. (1997), Medical Instrumentation: Application and Design (3^rd edition), Wiley, ISBN 471-1536-80 (UL: 610.28 WEB)

Formative Mechanisms

Students monitor their own progress by attempting the problems set which will be discussed in class. Students who need additional guidance are encouraged to discuss the matter with the lecturer.

Evaluation Mechanisms

The module will be evaluated using information gathered via the student representation mechanisms, the staff peer appraisal scheme, and measures of student attainment based on summative assessment.