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Active filters: part 8. Positive results from negative feedback
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WORLD ABSTRACTS ON M I C R O E L E C T R O N I C S AND R E L I A B I L I T Y
R.F. power meter uses thin-film thermocouple. A. A. LusKow, Marconi Instrum. 12, No. 2 (1969), p. 26. By making use of microwave thermocouples a new range of r.f. power meters has been produced with a frequency bandwidth from d.c. to 1 GHz measuring power from 100 mW to 100 W. Based on thin-film components and microwave techniques, the thermocouple detector is placed in series with a terminating load. A small part of the total incident power is absorbed by the detector and the thermoelectric e.m.f, produced is monitored directly on a moving coil meter, calibrated in terms of total incident power. As a thermocouple is a square law device the power meter measures true mean power independent of waveform distortion. The major limitation of the long measurement time constant of thermocouples is overcome by also providing a fast response diode detector, the instantaneous output of which is monitored on a second front panel meter. Practical considerations of system design with bipolar digital integrated circuits. W. G. T. JONES, Microelectron. & Reliab. 8, No. 1, February (1969), p. 1. Basic characteristics of widely used types of bipolar digital integrated circuits are given and compared. Static properties are explained with reference to the voltage transfer characteristic and methods of measuring dynamic properties are suggested with ways in which the results can be quoted. The need to prevent false operation, considered in conjunction with difficulties of cost and construction, determines the type of interconnexions used. The importance of optimum system design is mentioned, with some miscellaneous properties of circuits that can affect the design. Two examples are given of circuits for which no standard device may be available, and a method of acceptance~testing small batches of devices is suggested. Fundamental practical hints for development, construction and production using ICs for reliable numerical control. J. L. PATRICK,Automatik 14, No. 2, February (1969), p. 40. (In German.) To achieve a higher reliability by using integrated circuits in the field of numerical control, a number of problems must be taken into account. They are : choice and combination of logical elements and their auxiliary circuits--in development--manufacturing methods, supervision checking. The choice of logical elements, measuring methods and constructional details are discussed, together with some production hints. Active filters: part 8. Positive results from negative feedback. G. HUnTIG, Electronics, March 31 (1969), p. 96. Active filters to which positive feedback is applied require fewer components than those using negative feedback. Unfortunately, however, such circuits tend to oscillate. But now integrated circuits with many active devices on a single chip are commercially available, making it both practical and economical to design stable negative-feedback filters. LSI and systems. The changing interface. G. F. WATSON,Electronics, March 31 (1969), p. 78. As the discrete-device maker becomes a producer of complex integrated circuitry and, in effect, a subsystem supplier, his relationship with the customer--the systems manufacturer--is undergoing a fundamental shift. Unless LSI logic can be standardized--and there's still a possibility it can---systems houses will insist on playing an increasingly active role in the design and manufacture of ICs. Even at this early stage of the game, such companies are developing in-house facilities at least capable of making prototype circuits.
Phase locking: integrated tuned circuits made easy. H. R. CAMENZIND and A. B. GREBENE, Electronics, April 28 (1969), p. 94. The tuned circuit, heart of communications receivers, has long resisted integration on a monolithic chip. Approaches using external inductors or integrated active filters have not proved particularly successful. Now, however, a 30-yr-old idea--the phase-locked loop--has enabled Signetics engineers to build precisely tuned ICs, without precision components, for such applications as f-m radios and telemetry receivers. Single building block proves logical choice for custom ICs. D. K. LAUFFER,Electronics 42, No. 9, April 28 (1969), p. 88. For special purpose systems, a multipurpose circuit can usually give you more stability against transients, variations in power supply voltage and temperature extremes than can stock devices. While the price may seem high for these custom circuits, volume usage will offset most of the added cost.
WORLD ABSTRACTS ON M I C R O E L E C T R O N I C S AND R E L I A B I L I T Y
R.F. power meter uses thin-film thermocouple. A. A. LusKow, Marconi Instrum. 12, No. 2 (1969), p. 26. By making use of microwave thermocouples a new range of r.f. power meters has been produced with a frequency bandwidth from d.c. to 1 GHz measuring power from 100 mW to 100 W. Based on thin-film components and microwave techniques, the thermocouple detector is placed in series with a terminating load. A small part of the total incident power is absorbed by the detector and the thermoelectric e.m.f, produced is monitored directly on a moving coil meter, calibrated in terms of total incident power. As a thermocouple is a square law device the power meter measures true mean power independent of waveform distortion. The major limitation of the long measurement time constant of thermocouples is overcome by also providing a fast response diode detector, the instantaneous output of which is monitored on a second front panel meter. Practical considerations of system design with bipolar digital integrated circuits. W. G. T. JONES, Microelectron. & Reliab. 8, No. 1, February (1969), p. 1. Basic characteristics of widely used types of bipolar digital integrated circuits are given and compared. Static properties are explained with reference to the voltage transfer characteristic and methods of measuring dynamic properties are suggested with ways in which the results can be quoted. The need to prevent false operation, considered in conjunction with difficulties of cost and construction, determines the type of interconnexions used. The importance of optimum system design is mentioned, with some miscellaneous properties of circuits that can affect the design. Two examples are given of circuits for which no standard device may be available, and a method of acceptance~testing small batches of devices is suggested. Fundamental practical hints for development, construction and production using ICs for reliable numerical control. J. L. PATRICK,Automatik 14, No. 2, February (1969), p. 40. (In German.) To achieve a higher reliability by using integrated circuits in the field of numerical control, a number of problems must be taken into account. They are : choice and combination of logical elements and their auxiliary circuits--in development--manufacturing methods, supervision checking. The choice of logical elements, measuring methods and constructional details are discussed, together with some production hints. Active filters: part 8. Positive results from negative feedback. G. HUnTIG, Electronics, March 31 (1969), p. 96. Active filters to which positive feedback is applied require fewer components than those using negative feedback. Unfortunately, however, such circuits tend to oscillate. But now integrated circuits with many active devices on a single chip are commercially available, making it both practical and economical to design stable negative-feedback filters. LSI and systems. The changing interface. G. F. WATSON,Electronics, March 31 (1969), p. 78. As the discrete-device maker becomes a producer of complex integrated circuitry and, in effect, a subsystem supplier, his relationship with the customer--the systems manufacturer--is undergoing a fundamental shift. Unless LSI logic can be standardized--and there's still a possibility it can---systems houses will insist on playing an increasingly active role in the design and manufacture of ICs. Even at this early stage of the game, such companies are developing in-house facilities at least capable of making prototype circuits.
Phase locking: integrated tuned circuits made easy. H. R. CAMENZIND and A. B. GREBENE, Electronics, April 28 (1969), p. 94. The tuned circuit, heart of communications receivers, has long resisted integration on a monolithic chip. Approaches using external inductors or integrated active filters have not proved particularly successful. Now, however, a 30-yr-old idea--the phase-locked loop--has enabled Signetics engineers to build precisely tuned ICs, without precision components, for such applications as f-m radios and telemetry receivers. Single building block proves logical choice for custom ICs. D. K. LAUFFER,Electronics 42, No. 9, April 28 (1969), p. 88. For special purpose systems, a multipurpose circuit can usually give you more stability against transients, variations in power supply voltage and temperature extremes than can stock devices. While the price may seem high for these custom circuits, volume usage will offset most of the added cost.