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Radio and Electronic Engineer

Issue 1.2 • Date January-February 1978

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Displaying Results 1 - 13 of 13
  • Advances in microwave integrated circuits

    Publication Year: 1978 , Page(s): 1 - 2
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    Freely Available from IEEE
  • Review of some microwave integrated circuit components utilizing microstrip techniques

    Publication Year: 1978
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1731 KB)  

    This paper briefly reviews some of the techniques involved in realizing the practical microwave integrated circuit for systems applications. The main technological considerations and their application to advanced receiver sub-systems are discussed with emphasis on superheterodyne operation. View full abstract»

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  • Ageing tests on microwave integrated circuits

    Publication Year: 1978 , Page(s): 13 - 22
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1783 KB)  

    The study of failure mechanisms in microwave integrated circuits (m.i.c.s) provides essential information on the ageing behaviour of substrate-layer combinations. The ageing behaviour depends on the structure and the chemical composition of the substrate-layer combinations as well as on the ambient conditions. Tests on microwave properties, d.c. resistivity, adhesion as well as structure analysis are carried out before and after heat treatment. The structure analysis provides information about the initial nature of the samples and the ageing-induced structure changes. The ageing curves of tested m.i.c. metallizations are classified according to basic types of characteristics. These can be used as fingerprints characterizing the technology. It is shown that even small mechanical damage to the metal surface may cause nucleation of large defects resulting in a degradation of the structure, which shortens the life of the m.i.c. View full abstract»

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  • Modular construction of low-noise multi-stage f.e.t. amplifiers

    Publication Year: 1978 , Page(s): 23 - 28
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (827 KB)  

    A new amplifier modular structure has been developed to realize a 30 dB gain multi-stage f.e.t. amplifier for radar applications. Since the overall gain needed was very high, a multi-stage approach had to be adopted. Matched inputs and outputs of 50¿ were employed for each stage in order that individual stages could be characterized separately and adjusted if necessary. The cascading problem of these individual stages was resolved by the design of a rail modular technique. The amplifier has a gain greater than 30 dB over 1 GHz bandwidth at 9.3 GHz. The noise is less than 6 dB at temperatures up to 80°C. The modular construction described in this paper facilitates very rapid circuit design and assembly. It is readily adaptable to many different sub-assemblies using other devices (mixer diodes, negative resistance diodes, ferrite devices, etc.). View full abstract»

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  • Broadband microwave frequency doublers

    Publication Year: 1978 , Page(s): 29 - 32
    Cited by:  Papers (7)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (535 KB)  

    The paper describes the design and the performance of a frequency doubler, realized in hybrid m.i.c.-technique, which generates microwave power over the whole of K-band (18¿26 GHz). The conversion efficiency is approximately 10% for input power levels from 5 to 50 mW. Limiting effects occur at levels above 50 mW and depend on the frequency. The second part of the paper describes a design concept for frequency doublers and mixers which is also based on a planar balun configuration but employs four instead of two diodes. This enables increase of the input power without decreasing the conversion efficiency. View full abstract»

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  • A versatile solid-state mic source module for Ku-band

    Publication Year: 1978 , Page(s): 33 - 37
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (684 KB)  

    A phase-locked-loop approach has been adopted in order to realize a Ku-band transferred electron source with good power, stability and operational bandwidth. By arranging to interface with a u.h.f. reference, namely one of the new generation surface acoustic wave oscillators, the multiplier is simplified and the whole of the microwave circuit can be configured on a single compact m.i.c. The problem of maximizing the output of the transferred electron oscillator source in the rigid stripline medium has been solved by providing manual tuning elements together with an edge mounted device. Details of the circuit design and operation of the module are given. View full abstract»

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  • X-band microwave integrated circuits using slotline and coplanar waveguide

    Publication Year: 1978 , Page(s): 38 - 42
    Cited by:  Papers (19)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (985 KB)  

    Experimental results are given for propagation in a selection of slotline and coplanar geometries. Examples are given of X-band planar circuits incorporating semiconductors including balanced mixers, and p-i-n-diode switches and attenuators. Finally, an example of how slotline dipoles may be used to produce a simple aerial array is presented. View full abstract»

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  • The production of microwave integrated circuits by laser machining

    Publication Year: 1978 , Page(s): 43 - 46
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (536 KB)  

    This paper discusses laser machining as an alternative to photolithography for the production of m.i.c.s. A complete equipment is described comprising a laser with computer-controlled XY table moving a prepared substrate through the laser beam. The procedure to transfer the design sketch of a microwave circuit into a finished substrate is described together with some results. View full abstract»

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  • Prospects for GaAs mosfet integration

    Publication Year: 1978 , Page(s): 47 - 52
    Cited by:  Papers (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (713 KB)  

    Microwave integration has so far been pursued with Schottky gate f.e.t.s where difficulties however exist with : (1) the Schottky contact which must not be biased strongly in forward direction without danger of damaging it, (2) the high d.c. standby power dissipated as compared with normally-off digital transistors with reasonably large signal levels which are unfortunately not possible with m.e.s.f.e.t.s, and (3) with the rather small d.c. input impedance. The use of a GaAs m.o.s.f.e.t. technology avoids these and other difficulties and allows more flexibility in the circuit design. Until recently it was not possible to produce satisfactory m.o.s. structures on GaAs with sufficiently low leakage currents and satisfactory interface properties. Satisfactory results have now been achieved with an anodic oxidation process which has resulted in various transistors operating in each of the three modes of enhancement, inversion and depletion. Technological details of the manufacture of these devices are described and experimental results presented which demonstrate some of their useful ranges of operation. Possibilities of integration are reviewed and finally the areas of immediate applications for such integrated circuits discussed. View full abstract»

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  • Design of stepped microstrip components

    Publication Year: 1978 , Page(s): 53 - 63
    Cited by:  Papers (11)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1042 KB)  

    The analysis of the impedance step by the mode matching procedure using a waveguide model for the microstrip line yields an explicit design formula for the frequency-dependent equivalent series inductance. The single-section quarter-wavelength transformer is calculated under the assumption of interacting steps. It turns out that in regard to practical design the neighbouring steps can be considered to be decoupled so that the calculation can be done simply with the results given before. Finally the derived results for the impedance step are used to calculate the scattering matrix of an n-section tapered transmission line. Experimental data show good agreement with theory. View full abstract»

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  • Techniques for investigating spurious propagation in enclosed microstrip

    Publication Year: 1978 , Page(s): 64 - 72
    Cited by:  Papers (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (900 KB)  

    The effects of discontinuities and consequent spurious propagation in enclosed microstrip have been studied using 10:1 scaled models by probing the vertical component of the electric field in the substrate and by measuring insertion loss. A number of discontinuities were studied and the results showed the higher-order modes excited in the enclosed microstrip to be perturbed versions of the LSM and LSE modes of inhomogeneous waveguide. A coefficient of coupling from the discontinuity to each mode can be defined and estimated by measuring the external Q of the enclosure. The coupling varies with the discontinuity and its position. Since these modes all have electric fields with components tangential to the air/substrate interface, they can be suppressed by layers of resistive material. The effectiveness of this is demonstrated and also that the fundamental microstrip mode is little affected. Tests on unsealed models confirm the results obtained from scaled versions. View full abstract»

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  • Theoretical and experimental methods for evaluating discontinuities in microstrip

    Publication Year: 1978 , Page(s): 73 - 84
    Cited by:  Papers (9)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1243 KB)  

    Microwave circuits generally include a number of junctions and discontinuities at the interconnection of the various circuit limits and the resulting parasitic reactances can have a major effect on the circuit operation. The designer of waveguide and coaxial circuits has had available, for many years, a wealth of information on the parasitic reactances associated with the circuit elements and discontinuities, such as bends, T-junctions, transitions. Many elements can be evaluated theoretically and very accurate measurement techniques have also been devised in both media. Furthermore, small adjustments to the final circuits may easily be made using tuning screws, movable short-circuits, etc. In microwave integrated circuits the theoretical evaluation of circuit elements and discontinuities is difficult, experimental measurement is of limited accuracy and adjustment of the final printed circuit not easy to achieve. This paper will review the available theoretical and experimental methods for evaluating such discontinuities and present the available range of results. The equivalent capacitances can be obtained theoretically using fairly well known techniques but the inductance calculations are more difficult, although some progress has been made in this area recently. Theoretical data are important as accurate experimental measurements require considerable effort and there are a large range of configurations in use. To illustrate the effect of discontinuities on practical design the case of a microwave f.e.t. amplifier will be taken. Significant design errors can be shown to occur if the discontinuities are not allowed for. However, by using the data we now have available on the parasitics, fairly simple modifications can be introduced in the initial design to enable the desired performance to be more directly obtained. View full abstract»

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  • Computer-aided design of microwave integrated circuits

    Publication Year: 1978 , Page(s): 85 - 88
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (457 KB)  

    This paper describes how an analysis/optimization program in current use may be adapted for the design of m.i.c.s. The optimization routine combines two different strategies to reduce the execution time and increase the accuracy of approach to the true minimum. The analysis routine incorporates an algorithm for junction parasitics, dispersion, conductor and dielectric loss in the microstrip lines. The effects of these parameters, together with design details, are given and optimized results presented for several amplifiers, including an X-band single stage version, employing GaAs Schottky-gate field-effect transistors. This amplifier achieves 7 dB ± 0.5 dB gain, with 2.5 : 1 input and output v.s.w.r., over the frequency range 8¿11.6 GHz. View full abstract»

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