Liliya V. Levchenko

Computer Information Technologies and Automation Faculty

TCS-07m

e-mail: malenkaya86@mail.ru

The name of master's work: "Research and development of UHF transceivers' sub harmonic pumped mixers of telecommunications system"

Scientific director: professor of AT department Aleksandr G. Voroncov

Master's thesis

• Introduction
  • Actuality and novelty
  • Planned practical result
  • Scientific result
• Basic part
  • Survey decision of the problem
  • Basic results
• Conclusions
• Conclusions and research prospects
• References

Introduction

Actuality and novelty

At the present time frequency resource of circumterrestrial space in the developed ranges is exhausted. So, tendencies to moving bearing frequencies of radio channels transceivers to millimeter area of UHF range take place. It gives practical possibility of broadband communication networks design.
Thus, design of such transceivers, and, consequently, mixers, as their inalienable constituent is an important problem, and its importance will only increase in course of time in accordance with watched for progress of telecommunications trends.
The decision of some problems which are characteristic for mixer knot development becomes more complicated when bearing frequency moves to millimeter range, as follows [1].

1. Heterodyne realization with high enough stability of signal frequency
2. Providing of sufficient heterodyne signal power level
3. Heterodyne own noises level minimization

In addition, complication of mixer elements realization with the sufficient degree of exactness, in particular, chains of upshot increases.
Using sub harmonic pumped mixer which works on even heterodyne signal harmonics takes easy the mixer knot design problems because of the heterodyne signal frequency decreasing. This decreasing results in simplification of sufficient heterodyne signal power level providing and also increasing of linear mixer sizes that takes more easy providing sufficient precision at the mixer realization.
Thus, master’s thesis goal is expanding the sub harmonic pumped mixers using area in the telecommunication systems radio channels UHF transceivers.

Planned practical result

Problem of a 47GHz mixer design is set for the research work. This mixer is planned to use in a developed radio link transceiver. After mixer design some researches will be realized and as result some recommendations to such mixers design will be made.

Scientific result

A design algorithm of mixer that works on the second harmonic of heterodyne signal for millimeter range and also some recommendations to design is planned to make at this work. This experience can be applied at the design of higher frequencies mixers that will allow decreasing the expenses of time and facilities for mixer development.
Also possibility of development of a mixer that works on forth and eighth harmonics of heterodyne signal is planned. This research realized a practical possibility of bearing frequencies moving to higher frequencies area because the problem of heterodyne with sufficient signal power level design will be simplified.

Basic part

Survey decision of the problem

Realization of millimeter range mixer is quite complicated problem and can’t be solved at the existent laboratory terms of the university; therefore it will be necessary to talk to the specialists for eventual realization of mixer. Thus, it will be impossible to optimize mixer structure at its research. Therefore the research problem is suggested to be solved as follows. First, to build the mixer model for lower signal frequency, explore its characteristics, optimize them. Second, to realize a mixer, make practical researches, in particular, signal circuit decoupling and matching research, mixer S-parameters research. The results of theoretical and practical experiments will be used for design 47GHz mixer model.

Basic results

Figure 1 – Schematic of a mixer circuit worked on the second heterodyne signal harmonic. Picture is animated (5 frames, 7 animation circuits)

This model (Figure 1) is realized in the Microwave Office software. The heterodyne signal frequency is 576MHz, radio signal frequency (RF) is 1296MHz and intermediate signal frequency (IF) is 144MHz.

Conclusions

Conclusions and research prospects

Researches of this model give good results:

• Conversion losses: grater than -11.5dB
• Decoupling RF-heterodyne: grater than -36dB
• Decoupling heterodyne-RF: grater then -43dB
• Decoupling RF-IF: grater than -95dB
• Decoupling IF-RF: grater than -46dB
• Decoupling heterodyne-IF: grater than -43dB
• Decoupling IF-heterodyne: grater than -25dB

These characteristics can be improved at the expense of matching circuits and heterodyne signal level optimization.
The research results allow setting some specialties of such mixers and confirming expedience of methods used in the research. This experience can be applied for 47GHz mixer design.

References

1. Проектирование радиоприемных устройств. Под ред. А П. Сиверса: Учебное пособие для ВУЗов. М.: Советское радио, 1976г.
2. Микроэлектронные устройства СВЧ. Под ред. Г.И. Веселова. – М.: Высшая школа, 1988. – 280с.