Wave transmission lines and networks – Coupling networks – Delay lines including long line elements
Patent
1992-01-17
1994-11-29
Ham, Seungsook
Wave transmission lines and networks
Coupling networks
Delay lines including long line elements
333116, 333238, H01P 118, H01P 308
Patent
active
053693817
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a slow-wave transmission line of the microstrip type, comprising a first conductive layer called lower layer used as a ground plane, a second conductive layer called upper layer in the form of strips having specific widths and lengths and a third non-conductive material arranged between these two conductive layers.
The invention likewise relates to couplers formed by such lines.
The invention also relates to the circuits including such a line.
In addition to these circuits the invention relates to a transceiver arrangement including an integrated circuit which comprises a frequency duplexer for transmitting a first and receiving a second signal on a single pole.
The invention finds its application particularly in the realisation of integrable transmission lines, that is to say, lines which may be included in integrated circuits and, more specifically, in monolithic and microwave frequency integrated circuits known under the name of MMIC.
Generally, the invention finds its application in the miniaturisation of transmission lines and permits augmenting the integration density of the integrated circuits comprising these lines, and/or augmenting the operating performance of these circuits.
In the case where the integrated circuit comprising the frequency duplexer is used, the invention finds its application in single-antenna transmission and reception in the microwave frequency domain, an integrated duplexer isolating the transmitted signals from the signals transmitted by this single antenna.
BACKGROUND OF THE INVENTION
A transmission line of the microstrip type is described in the publication entitled: "Properties of Microstrip Line on Si-SiO.sub.2 System" by HIDEKI HAZEGAWA et al. in "IEEE Transactions on Microwave Theory and Techniques, Vol. MMT-19, No. 11, November 1971, pp. 869-881".
According to the above document a microstrip line consists of a piled structure formed by a metallic layer used as a ground plane, a silicon (Si) semiconductor layer, a thin silicon dioxide (SiO.sub.2) dielectric layer and a metallic strip having a given transverse dimension.
This document describes that such a line permits propagation in three fundamental modes. The first mode is a "quasi-TEM mode", the second is a "skin-effect mode" and the third is a "slow-wave mode".
The larger the resistivity of the semiconductor layer the more the propagation mode approaches a conventional TEM mode.
The third mode termed "slow-wave mode" appears when the operating frequency is low, of the order of 10 to 10.sup.3 MHz, and when the resistivity of the semiconductor layer is also low, of the order of 10.sup.4 or 10.sup.2 .OMEGA..cm. In this "slow-wave mode" the magnetic energy is distributed over the semiconductor layer whereas the electric energy is stored in the dielectric layer. The sum of these energies is transmitted perpendicularly to the layers through the thin silicon dioxide (SiO.sub.2) dielectric layer. The phase velocity thus diminishes due to the energy transfer to the interface of the semiconductor and the dielectric (Si/SiO.sub.2).
The phase constant is expressed in terms of normalized wavelengths: .lambda..sub.g /.lambda..sub.o, which ratio is equal to the propagation velocity in the line divided by the velocity of light in free space. The maximum usable frequency largely depends on the resistivity of the semiconductor layer and becomes highest when the resistivity reaches 10.sup.-1 .OMEGA..cm, while this frequency remains below the GHz domain.
Alternatively, the phase constant and the characteristic impedance of the line also very much depend on the transverse dimension of the strip and the thickness of the semiconductor layers and the dielectric separating the ground plane from the strip.
In conclusion, this document describes that the operation in the slow-wave mode presents high losses which could be diminished by devising a multi-layer structure between the ground plane and the strip, this multi-layer structure being formed by an alternation of semiconductor layers and thin dielectric layers
REFERENCES:
patent: 3004229 (1961-10-01), Stearns
patent: 4229717 (1980-10-01), Krone et al.
patent: 4604591 (1986-08-01), Vasile
Farber, "Propagating Signals Across Semiconductor Wafers", IBM Tech. Disclosure Bulletin, vol. 8, No. 6, Nov. 1965, pp. 924-925.
Jager, "Nonlinear Slow-Wave Propagation on Periodic Schottky Coplanar Lines", IEEE 1985 Microwave & Millimeter-Wave Monolithic Circuits Symposium-digest, Jun. 3-5 1985, pp. 15-17.
Gammand et al., "Slow Wave Propagation . . . IC Technologies", Electronics Letters, vol. 26, No. 18, Aug. 30, 1990, pp. 1443-1445.
Patent Abstracts of Japan, JP-A-57 197934, vol. 7, No. 49, E-161, Feb. 25, 1983.
Ham Seungsook
Miller Paul R.
U.S. Philips Corporation
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