5 PRKMOLI, A.: 'Multiple-pole-and-zero approximation of generalattenuation specifications', ibid., 1980, CAS-27, pp. 1218-1224

6 B1EY, M., and PREMOLI, A.: 'Low-(? approximation of filterswith prescribed attenuation shape', IEE Proc. G, Electron. Circuits& Syst., 1981, 128,(4), pp. 149 151

7 KOMINF.K, Z.: 'Low-pass approximation convenient for circuitswith low Q\ Proceedings of 4th colloquium on microwave com-munication, Vol. 2, Budapest, 21st —24th Apr., 1970

8 CiERMANO, F\: 'Progetto di un filtro RC attivo a bassa sensibilitamediante ottimizzazione su calcolatore'. Dissertation, Politecnicodi Torino, Turin, Italy, 1970

Amedeo Premoli was born in Crema,Italy, in 1942. He received the Doctor'sdegree (Summa cum Lande) in electronicengineering from the Politecnico diTorino, Torino, Italy, in 1965, and wasawarded the prize 'Salvatore Chiaudano'for the best degree in his University.

Since 1966 he has been with theDepartment of Radiotechnology of theIstituto Elettrotecnico Nazionale GalileoFerraris in Torino. In 1971 he joined

9 MADSEN, K., SCHJAER-JACOBSEN, H., and VOLDBY, J.:'Automated minimax design of networks', IEEE Trans 1975CAS-22, pp. 791-796

10 MADSEN, K., and SCHJAER-JACOBSEN, H.: 'Singularities inminimax optimization of networks', ibid., 1976, CAS-23, pp.456-460

11 BIEY, M., and PREMOLI, A.: 'Lowpass filters by cascading low-03rd-order blocks', IEE Proc. G, Electron. Circuits & Svst 1982,129,(1), pp. 26-28

the Computer Center, and in 1977 the System and CircuitGroup of the same Institute.

From 1966 to 1972 he was also part-time Assistant Pro-fessor in Politecnico di Torino.

His interests are in the field of circuit and system theory,in particular on distributed networks, approximation oftransfer functions, active filters, and system reliability. He isauthor or coauthor of about 50 technical papers.

Book reviewAnalog-digital and digital-analog conversionB. LoriferneHeyden Press, 1982, 196pp., £13.50ISBN: 0-85501-497-0

What a pleasure it was to find a book that is well organisedand easy to read on the very important topic of the analogue-digital interface. It has a good balance of theory and practice,presented in a clear logical manner. French students havebeen fortunate to have this text available since 1976. Thetranslation from the French has been done very well; I couldonly find one or two ambiguities.

The book is organised in a top-down manner, starting,quite properly in my view, by giving an overview of theoverall process of analogue-to-digital and digital-to-analogueconversion from a theoretical point of view. The key pro-cesses are sampling and signal reconstruction. The effectsof sample-hold circuits and their operation are treated inthis chapter, but it lacks analytic strength and the descriptionof the aperture of sample-hold is rather vague. Errors aredescribed thoroughly, as they are in the following chapterson DACs and ADCs.

Chapters 2 and 3 follow the same basic pattern inpresenting digital-to-analogue conversion and analogue-to-digital conversion, respectively. A general analytical definitionof conversion is given and the key components of the processidentified. A classification of the various implementationsof each convertor is given and provides the structure for therest of the chapter. The coverage is extensive: parallel, serial,and indirect DACs and analogue, logic, very high speed andbipolar ADCs are discussed in detail. Before this, eachchapter has a good treatment of the errors in DACs andADCs covering quantisation, offset, gain, linearity anddifferential errors and temperature effects; the latter beingvery relevant to integrated devices. Finally, each of thesechapters examines the problem of measuring the performanceof convertors — a difficult process and one often omittedfrom other texts on the subject.

In communications systems, logarithmic conversion isfrequently encountered, and these methods are outlined atthe end of Chapter 3.

The fourth chapter is devoted to methods of synchro-digital, digital-synchro conversion. Many forms of angle-to-

digital and digital-to-angle devices are described. This chapteris particularly relevant to control-systems engineers wheremonitoring of rotation and direct control of motors is anintegral part of their work.

Finally, the author considers the building blocks fromwhich the earlier devices were constructed: comparators,resistance networks, bipolar, FET and CMOS switches andreference sources are all covered in some detail. Here realexamples are used and detailed circuits analysed. By placingthis material in a common chapter, the author has avoidedundue clutter and repetition in earlier chapters; probablythe most important factor in making the text so easy tofollow.

There is an ample supply of -references, but all earlierthan 1975; I think the author could have provided an updateto make them more current. Fortunately, the text has notaged and the material is quite relevant to any degree courseon D-to-A and A-to-D methods. However, the analyticaltreatment is terse, many equations are just stated, withreferences given, and it may be necessary to justify themin lectures, if using the text as a course book, for which Ithink it is admirably suited.

I found the slack use of logic notation and symbols veryannoying. Both the plus and minus symbol were used for theOR function, and in the logic diagrams a random mixtureof flip-flop symbols was used which makes them confusingand difficult to follow. This is particularly annoying whenthe logic circuit provides the only definition of the logicfunction performed by the circuit.

These are only minor criticisms of a good text that shouldbe well received by the teaching community. Unfortunately,its age makes it less suitable as a state-of-the-art text forengineers in industry. It is pleasing to see a text presented ina top-down fashion, i.e. system ideas — subsystems components,and I am sure my enthusiasm for it arises from my wish tosee the subject taught this way. However, I am not convincedthat students of engineering wish to be educated this way;they seem to prefer to be given a box (brain) full of bitsand then be shown how to put them together. I hope thebook is a success.

PROF. E.L DAGLESS

68 IEE PROC, Vol. 130, Pt. G, No. 2, APRIL 1983