Letter to the Editorial Board of the Collection Proceedings of the Tomsk Polytechnic Institute of the Order of the Red Banner of Labour named after S. M. Kirov
Abstract Generated abstract
This letter responds to V. M. Sergeev’s article on nonlinear distortions in a common-emitter transistor amplifier, focusing on its treatment of internal feedback and its criticism of V. D. Ivanchenko’s earlier work. The author compares Sergeev’s claims with the cited source and argues that Sergeev misrepresented key assumptions, including the dependence of transistor parameters and the form of the output-voltage relation. The letter concludes that several criticisms of the earlier work are unjustified, that the posed problem was treated incompletely, and that the editorial board should publish the response together with Sergeev’s explanation.
Full Text
Letter to the Editorial Board of the Collection “Proceedings of the Tomsk Order of the Red Banner of Labor Polytechnic Institute named after S. M. Kirov”
Dear Editors,
In volume 231 of your collection for 1971, an article by V. M. Sergeev, “Nonlinear Distortions of a Transistor Amplifier in a Common-Emitter Circuit,” was published [1].
A detailed study of this work makes it possible, in particular, to establish the following.
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The problem is posed of taking into account the influence of the transistor’s internal feedback on nonlinear distortions.
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An improper separation is noted in work [5]*) of the distortions caused by the input and active circuits of the transistor, since the transconductance and the input resistance are interrelated.
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It is stated that “In work [5] it is erroneously assumed that the transfer coefficient of the output circuit is a function of \(U'_2\), and the output voltage is found from the relation
\[ U_2 = \int \gamma_2(U'_2)\,dU'_2", \]
and the invalidity of this notation is noted.
From a comparison of works [1] and [5], the following conclusions follow.
On point 1.
The problem posed is appropriate.
On point 2.
As for the interrelation between the transconductance and the input resistance, in [5] this interrelation is not denied, since from expressions (5) and (7) of [5] it is evident that these parameters are interdependent. It is simply that in [5] the generally known interrelation was not emphasized once more.
As for the separation of the input and active circuits, in work [1] there is likewise no such separation, since the same expressions for the transconductance are used as in [5].
Thus, within the scope of point 2, V. M. Sergeev did not solve the problem posed. In this part, the criticism of work [5] is not justified.
On point 3.
a) In work [5] it is in no way assumed that the transfer coefficient of the output circuit is a function of the output voltage. Moreover, on p. 26 of [5] it is clearly stipulated that subsequently the influence
*) V. D. Ivanchenko. Nonlinear distortions in transistor amplifiers. In the collection: “Semiconductor Devices in Telecommunications Engineering.” Edited by I. F. Nikolaevsky. Issue 2, Moscow, “Svyaz,” 1968.
we shall neglect the effect of the output voltage on the parameters of the transistor, regarding them as functions only of the “emitter—base” voltage.
It is clear from this that V. M. Sergeev did not take into account the starting proposition of work [5], giving this assumption a directly opposite meaning.
b) As for the notation
\[ U_2=\int \gamma_2(U'_2)\,dU'_2, \]
there is no such notation in work [5], and from the results of [5] this integral cannot in principle be obtained, since the integrand does not depend on the output voltage [5, p. 26].
Thus, V. M. Sergeev attributed to work [5] unjustified results of his own investigations.
Without dwelling on other errors and inaccuracies in [1], let us note that an arbitrary interpretation of the results of another work and the attribution to it of one’s own unwarranted conclusions are at the very least strange and have led to the incompleteness of the investigations in [1]. Thus, the problem posed in item 1 is considered only as applied to aperiodic amplifiers, where feedback practically does not manifest itself, while the results of work [5] as applied to selective amplifiers are not specified in [1]. At the same time, the principal result (11) of [1] may raise doubts, since under the common assumptions \((R_i=0,\ R_n=0)\) it has so far not been possible to obtain from (11) [1] the well-known expression
\[ K_2=\frac{1}{4}\frac{S'}{S}U_1. \]
In view of the fact that the criticism of work [5] is based on results that are absent from it and do not follow from it, I ask the Editorial Board to publish this letter with V. M. Sergeev’s explanations.
Respectfully, V. Ivanchenko 20/XII 1971