Bokhoven, WMG Wim  van

Tirtoprodjo, S

Bokhoven, van, W.M.G.

Tirtoprodjo, S.

NARCIS 

A simple impedance convertor

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 A simple impedance convertorCitation for published version (APA):Bokhoven, van, W. M. G., & Tirtoprodjo, S. (1967). A simple impedance convertor. (Technische HogeschoolEindhoven : Afdeling der Elektrotechniek : rapport; Vol. ETB 15). Technische Hogeschool Eindhoven.Document status and date:Published: 01/01/1967Document Version:Publisher’s PDF, also known as Version of Record (includes final page, issue and volume numbers)Please check the document version of this publication:• A submitted manuscript is the version of the article upon submission and before peer-review. There can beimportant differences between the submitted version and the official published version of record. Peopleinterested in the research are advised to contact the author for the final version of the publication, or visit theDOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and pagenumbers.Link to publicationGeneral rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright ownersand it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.            • Users may download and print one copy of any publication from the public portal for the purpose of private study or research.            • You may not further distribute the material or use it for any profit-making activity or commercial gain            • You may freely distribute the URL identifying the publication in the public portal.If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license above, pleasefollow below link for the End User Agreement:www.tue.nl/taverneTake down policyIf you believe that this document breaches copyright please contact us at:openaccess@tue.nlproviding details and we will investigate your claim.Download date: 05. Oct. 2023.. : ' ",:', ..... -.~. - ~I -" i, '. • '. e" , !~_!~~E~! .. __ ~E!~!::!~! ___ =2:!!!::~2::_ .. • abstract • internal report by w. v.Bokhoven Be s. Tirtoprodjo • (July 1967·) In the following a device is given, which converts an impedance in~ its dual. It can be used to simulate gro~nded inductances. • , ,~ , ." .- 2 -Introduction • .... -..... -------_. As far as we know, up till now every active device with gyrator properties consisted of at least ·two differential amp~ifiers [1] ,_ or four operational amplifiers [21, or .. contained two negative impedance convertors [3J t requiring a lot of components ~or\proper all these action • circuits RecentlyW. Jost [4J has realised a gyrator with O~lY two \ operational amplifiers in'connection with a resistance 'network • in which tolerances of the resistance-values must be kept very small to guarantee good operation • In some aspects, the circuit given here borrows from the various circuits of the references mentioned above • It basically consists of only one neg~tive resistance convertor and one emitter follower • 1 " ." Consider the T - circuit' of figure 1 • After transforming' it into its equivalent, 'delta-network , the circuit of fig. 2 is obtained .. z Rt2Z " 3 2~~------------~~ fig. 1 fig. 2 If now:an ideal emitter follower is placed between points' 1 and 3, these two pOints will achieve the same potential , ',and therefore, in the equivalent configuration of .fig.2 , obvi~usly no current will flow from point 1. to point 3 • Thus, looking into the circuit between points 1 and 2 of fig.2, be the impedance " FinallYt by adding a negative resistance .~ 2 R in series with t~e impedance between 1-2, to compensate the + 2 R t only 'Ii /z will be le ft, which is preoisely the dual of. the '. original impedance • • - 4 -.The· complete circuit is depicted in figure 3 2R 3 fig. 3 This circuit has the advantaGe, that apart from the negative resistance" it can easil~ be 1;.'~ild in integrated - circuit form t because stability is evident and fUrthermore, ele~ent tolerance cannot disturb propDr action. .... ' The negative resistance has to' be constructed in such a way t that it can be con trolled fro::. ';;;ne ou tside • The overall circuit is stable. if the a~~olute value of: the negative resistance is smaller th&.ll. 2 R • If Z of fig.3 is taken to' be a capacitor t the input impedance will be an inductance in series with a small amount of resistance, which can be compensated with the negative resistance • In this walt inductor values from 5 millihenry to' 1 henry with qualitl factol'$ot 800 andmO're has been obtained in the range from zerO' to . a few hundredkilocs./secw at stable circuit operation. j - 5 -P~actical realisation. _____ ~ __ ~~_~~_~ ___ ~~~~d __ The practical circuit is shown in fig. 4 • --r--- 3{) Volt ! fi~. 4 The transistor T, is used as a current-source to bias the negative impedance convertor formed by T2 and T}. Transistor T4 is the emitter follower • The circuit can be improved by replacing T4 with a cl~rlington-connectiont a field-effect transistor or a combinatio~l of both ; :.:~ t for almost every practical application one transistor T4 will l);.~ov.e sufficient • For verification, we have. constructed a first-order Tchebycheff-filter, first with a conventional wire-wound inductor with quality-factor 200 at the pole frequency and then replacing the inductor with the above simulator circuit • The lastmentioned case gave equal or even better characteristics, especially at the pole frequency, due to the higher Q (about gOO) of. the simulated inductance • .. : .... I '~, ' -6-c o,nclusions 0, 'An ,active device ,is given to generate dual impedances, i,or instance to convert a capacitive impedance into an, inductive impedanoe with high Q - :f'actor; with few components needed t; thus faoilitating future integrated-circuit realisation. Moreover, i~ we consider the emitter-follower and the negative resistance . of fig" 4 to be ideal; then a simple proof' , as privately communicated to us by Prot.A.Fettwe1s, shows, that the circuii of fig.4 indeed repl~",,,,,;;;r.'~s an ideal gyrator with gyration-resistance R (here R = I k.) and loaded at the output by the arbitraT1 impedance Z At the; moment, w()rk is in progress on a modified form of the above gyrator, which we hope will be more suitable ·as simulation' for' the .JjI]J£Tounded 'inductance. For this we have in mind a balanced-bri,dge con:f'igul~;;.,tion t 'in which the balancing ia again maintained by an emitter-follower, similar to the one we used here '. • "-·7 -'References .. I 1] R.B.. S.Riordan Simulated Inductors using Differential Amplifiers • ("E1ectronie.s'Letters", 1967 ,no. 2,pp. 50-51) [2] A.S.Morse andL.P.Ruelsman; A Gyrator Realisation using Operational Amplifiers,. (IITrans.I"E.E" E. 1964, C'1'-11, pp.277-278.) [,] . B..J.Carlin, Synthesis of non-reciprocal networks • (Proc. of the Symp. on Modern Network Synthesis, Polytechnic Institute of Brooklyn, 1955. ) [4J W. Jo,st. , Die R,ea1isierung des idealen Gyrators mit zwei Operations - verstarkern .. ("Arch.El.U'bertr.", 196;7, Rett.', pp.152-15T.) The negative resistance 'realisation as usee: in fig.4 f" is· due· to "Western Elecitric" .. ( Dutch Patent pending , no.6608228, Dec.15, ,1966.) ................ _-- 0 ---.... ~ .. - ...... 

English

 A simple impedance convertorCitation for published version (APA):Bokhoven, van, W. M. G., & Tirtoprodjo, S. (1967). A simple impedance convertor. (Technische HogeschoolEindhoven : Afdeling der Elektrotechniek : rapport; Vol. ETB 15). Technische Hogeschool Eindhoven.Document status and date:Published: 01/01/1967Document Version:Publisher’s PDF, also known as Version of Record (includes final page, issue and volume numbers)Please check the document version of this publication:• A submitted manuscript is the version of the article upon submission and before peer-review. There can beimportant differences between the submitted version and the official published version of record. Peopleinterested in the research are advised to contact the author for the final version of the publication, or visit theDOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and pagenumbers.Link to publicationGeneral rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright ownersand it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.            • Users may download and print one copy of any publication from the public portal for the purpose of private study or research.            • You may not further distribute the material or use it for any profit-making activity or commercial gain            • You may freely distribute the URL identifying the publication in the public portal.If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license above, pleasefollow below link for the End User Agreement:www.tue.nl/taverneTake down policyIf you believe that this document breaches copyright please contact us at:openaccess@tue.nlproviding details and we will investigate your claim.Download date: 04. Oct. 2023.. : ' ",:', ..... -.~. - ~I -" i, '. • '. e" , !~_!~~E~! .. __ ~E!~!::!~! ___ =2:!!!::~2::_ .. • abstract • internal report by w. v.Bokhoven Be s. Tirtoprodjo • (July 1967·) In the following a device is given, which converts an impedance in~ its dual. It can be used to simulate gro~nded inductances. • , ,~ , ." .- 2 -Introduction • .... -..... -------_. As far as we know, up till now every active device with gyrator properties consisted of at least ·two differential amp~ifiers [1] ,_ or four operational amplifiers [21, or .. contained two negative impedance convertors [3J t requiring a lot of components ~or\proper all these action • circuits RecentlyW. Jost [4J has realised a gyrator with O~lY two \ operational amplifiers in'connection with a resistance 'network • in which tolerances of the resistance-values must be kept very small to guarantee good operation • In some aspects, the circuit given here borrows from the various circuits of the references mentioned above • It basically consists of only one neg~tive resistance convertor and one emitter follower • 1 " ." Consider the T - circuit' of figure 1 • After transforming' it into its equivalent, 'delta-network , the circuit of fig. 2 is obtained .. z Rt2Z " 3 2~~------------~~ fig. 1 fig. 2 If now:an ideal emitter follower is placed between points' 1 and 3, these two pOints will achieve the same potential , ',and therefore, in the equivalent configuration of .fig.2 , obvi~usly no current will flow from point 1. to point 3 • Thus, looking into the circuit between points 1 and 2 of fig.2, be the impedance " FinallYt by adding a negative resistance .~ 2 R in series with t~e impedance between 1-2, to compensate the + 2 R t only 'Ii /z will be le ft, which is preoisely the dual of. the '. original impedance • • - 4 -.The· complete circuit is depicted in figure 3 2R 3 fig. 3 This circuit has the advantaGe, that apart from the negative resistance" it can easil~ be 1;.'~ild in integrated - circuit form t because stability is evident and fUrthermore, ele~ent tolerance cannot disturb propDr action. .... ' The negative resistance has to' be constructed in such a way t that it can be con trolled fro::. ';;;ne ou tside • The overall circuit is stable. if the a~~olute value of: the negative resistance is smaller th&.ll. 2 R • If Z of fig.3 is taken to' be a capacitor t the input impedance will be an inductance in series with a small amount of resistance, which can be compensated with the negative resistance • In this walt inductor values from 5 millihenry to' 1 henry with qualitl factol'$ot 800 andmO're has been obtained in the range from zerO' to . a few hundredkilocs./secw at stable circuit operation. j - 5 -P~actical realisation. _____ ~ __ ~~_~~_~ ___ ~~~~d __ The practical circuit is shown in fig. 4 • --r--- 3{) Volt ! fi~. 4 The transistor T, is used as a current-source to bias the negative impedance convertor formed by T2 and T}. Transistor T4 is the emitter follower • The circuit can be improved by replacing T4 with a cl~rlington-connectiont a field-effect transistor or a combinatio~l of both ; :.:~ t for almost every practical application one transistor T4 will l);.~ov.e sufficient • For verification, we have. constructed a first-order Tchebycheff-filter, first with a conventional wire-wound inductor with quality-factor 200 at the pole frequency and then replacing the inductor with the above simulator circuit • The lastmentioned case gave equal or even better characteristics, especially at the pole frequency, due to the higher Q (about gOO) of. the simulated inductance • .. : .... I '~, ' -6-c o,nclusions 0, 'An ,active device ,is given to generate dual impedances, i,or instance to convert a capacitive impedance into an, inductive impedanoe with high Q - :f'actor; with few components needed t; thus faoilitating future integrated-circuit realisation. Moreover, i~ we consider the emitter-follower and the negative resistance . of fig" 4 to be ideal; then a simple proof' , as privately communicated to us by Prot.A.Fettwe1s, shows, that the circuii of fig.4 indeed repl~",,,,,;;;r.'~s an ideal gyrator with gyration-resistance R (here R = I k.) and loaded at the output by the arbitraT1 impedance Z At the; moment, w()rk is in progress on a modified form of the above gyrator, which we hope will be more suitable ·as simulation' for' the .JjI]J£Tounded 'inductance. For this we have in mind a balanced-bri,dge con:f'igul~;;.,tion t 'in which the balancing ia again maintained by an emitter-follower, similar to the one we used here '. • "-·7 -'References .. I 1] R.B.. S.Riordan Simulated Inductors using Differential Amplifiers • ("E1ectronie.s'Letters", 1967 ,no. 2,pp. 50-51) [2] A.S.Morse andL.P.Ruelsman; A Gyrator Realisation using Operational Amplifiers,. (IITrans.I"E.E" E. 1964, C'1'-11, pp.277-278.) [,] . B..J.Carlin, Synthesis of non-reciprocal networks • (Proc. of the Symp. on Modern Network Synthesis, Polytechnic Institute of Brooklyn, 1955. ) [4J W. Jo,st. , Die R,ea1isierung des idealen Gyrators mit zwei Operations - verstarkern .. ("Arch.El.U'bertr.", 196;7, Rett.', pp.152-15T.) The negative resistance 'realisation as usee: in fig.4 f" is· due· to "Western Elecitric" .. ( Dutch Patent pending , no.6608228, Dec.15, ,1966.) ................ _-- 0 ---.... ~ .. - ...... 

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A simple impedance convertor

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