WO2013089574A1

WO2013089574A1 - Magnetic transmission line device for terahertz integrated circuits

Info

Publication number: WO2013089574A1
Application number: PCT/PT2012/000050
Authority: WO
Inventors: Jose António Marinho Brandão FARIA
Original assignee: Instituto Superior Tecnico; Instituto De Telecomunicações
Priority date: 2011-12-12
Filing date: 2012-12-11
Publication date: 2013-06-20
Also published as: PT106056B; PT106056A

Abstract

This invention refers to a passive device that includes a magnetic transmission line for implementation in integrated circuits. The magnetic line structure, where electro-magnetic signals are guided, is constituted by two longitudinally parallel strips or films, (2) and (3), made of an isotropic soft magnetic material (e.g., ferrite). The magnetic strips or films are placed on opposite faces of an insulating slice of dielectric material (1). Preliminary research work has showed that, in comparison with the standard solution of utilizing metallic strips made of very good conducting material (e.g., silver), the proposed device, by utilizing magnetic strips for signal propagation, offers significant advantages in the terahertz band as far as the attenuation, dispersion and transmission velocity are concerned. Terahertz technology has numerous potential applications: in telecommunications; ultrafast computers; aerospace; defense, surveillance, and security; medical and biologic imaging; and, also, in food control.

Description

DESCRIPTION

MAGNETIC TRANSMISSION LINE DEVICE FOR TERAHERTZ INTEGRATED CIRCUITS

Field of invention

Terahertz technology.

Terahertz technology is concerned with the exploitation of the frequency spectrum located between the microwave and the infrared regions.

Technical field of invention

This invention refers to a magnetic transmission line (MGTL) device, which includes an insulating slice of a dielectric material, (1), in whose opposite faces two longitudinally parallel magnetic strips or films, (2) and (3), are deposited. The said device is to be used in integrated circuits (ICs) that are part of terminal equipment for use in terahertz technology, namely: ICs for terminal equipment of advanced telecommunication systems with bit rates of Tbit/s; ICs for ultrafast computer system CPUs; ICs for THz terminal equipment of defense, surveillance and security systems; ICs for THz terminal equipment of medical and biologic imaging systems; ICs for THz terminal equipment of food control systems.

State of the art

Terahertz technology state of the art has been focused on THz sources, THz detectors, THz instrumentation and measurement, THz amplifiers and, above all, THz applications: imaging, aerospace, communications, and spectroscopy (detection of explosive materials, chemical and biologic agents, illegal drugs, cancer detection, and DNA analysis) , However, in what refers to guided transmission of THz electromagnetic signals, the approach has been the classic one: the utilization of metallic strips or films.

The utilization of strips or films, made of isotropic soft magnetic materials, for THz signal transmission has never been thought .

Preliminary research work has showed that, in comparison with the classical solution, of utilizing metallic strips, the utilization of magnetic strips for signal transmission, may offer significant advantages in the terahertz band as far as the attenuation, dispersion, and transmission velocity are concerned ..

Patents that may be related to this invention:

GB851519A; US3376523A; JP2007049042A; JP2010223843A;

US7508578B2; US7675037B2 ; US1010072368A1 ; JP2010135520A.

The patent GB851519A describes a microwave device, for signal transmission and modulation, which employs a circular metallic waveguide containing inside a small ferrite piece whose magnetization is enforced by a coil, (device to be used as a microwave demodulator) . The present invention is, also, a waveguide, but it is not metallic, nor circular. In this invention, the electromagnetic signals are guided by means of a pair of parallel magnetic strips. Moreover, this invention is aimed at THz applications, not to microwave applications (where it would not be advantageous) .

The patent US3376523A, from 1968, is targeted at low frequency applications. It deals with a magnetic transformer provided with several dielectric membranes whose function is to severely attenuate high frequency transient regimes (through energy dissipation in the dielectric membranes) . The patent has nothing to do with the present invention, ' which applies to terahertz integrated circuits and where attenuation reduction is a major goal . The patent JP2007049042A refers to a THz light emitter. The present invention is not a THz source but a passive transmission line.

The patent JP2010223843A refers to a THz device, for measuring the physical and chemical properties of a substance. It includes a light emitter, a detector, a mixer and a transistor for THz operation. The present invention does not include any emitter, detector, mixer or transistor. The present invention is not a measuring device, but a passive transmission line.

The patent US7508578B2, from 2009, describes a laser based THz wave generator. The present invention does not generate THz waves, it transmits and guides THz waves.

The patent US7675037B2, from 2010, describes a method and an apparatus for measuring THz waves by time-domain spectroscopy. This invention is not a spectrometer, but a passive transmission line .

The patent US1010072368A1 , from 2010, describes a measuring method for determining the spectral properties (physical and chemical) of a substance submitted to THz radiation. This invention does not describe any measuring method, but a passive transmission line.

The patent JP2010135520A refers to a THz solid state receiver (an active element) , provided with several electrodes and an antenna for receiving THz waves. This invention is not a THz receiver, but a THZ transmission line.

Summary of the invention

The invention is a passive magnetic transmission line device for terahertz integrated circuits. The device, magnetic transmission line (MGTL) , includes an insulating slice of dielectric material, (1), in whose opposite faces two longitudinally parallel strips or films, (2) and (3), made of an isotropic soft magnetic material, are deposited. The strips or films are bent at both ends, (4) and (5), and are externally coupled via two metallic strips (6) and (7).

The innovatory characteristics of the invention steam from the utilization of magnetic strips instead of the classical metallic strips (good conductors).

As compared with the standard electric transmission line (ELTL) made of metallic conductors, the advantages of the MGTL in the THz range manifest themselves through smaller attenuation, smaller dispersion, and higher transmission velocity.

Detailed description of the invention

Figure 1 shows the structure of the present invention, an MGTL device, for implementation in integrated circuits. The magnetic transmission line includes an insulating slice of dielectric material, (1), in whose opposite faces two longitudinally parallel strips or films, (2) and (3), made of an isotropic soft magnetic material, are deposited. The strips or films are bent at both ends, (4) and (5), and are externally coupled via two metallic strips (6) and (7).

The insulating slice of dielectric material (1), should exhibit small losses in the THz range, that is, tan δ around 10^-3 to 10^~5, as it occurs, for example, with low temperature co-fired ceramics .

The soft magnetic strips, (2) and (3), should exhibit a high relative magnetic permeability, that is, μ_Γ around 10⁴ to 10⁵, as it occurs, for example, in ferrites.

The innovatory characteristics of the invention steam from the. utilization of magnetic strips (e.g. ferrite) instead of classical good conducting strips (e.g. silver).

When compared with the conventional ELTL, the advantages of the MGTL, in the THz range, manifest themselves through smaller attenuation, smaller dispersion, and higher transmission velocity (phase and group velocities) . These features are graphically illustrated in Figures 2, 3, 4 and 5.

An additional feature, deserving remark, is that an MGTL can run parallel to an identical pre-existent ELTL without any cross coupling effects.

The MGTL device can advantageously be used in integrated circuits that make part of terminal equipment for ^' use in terahertz technology, namely: ICs for terminal equipment of advanced telecommunication systems with bit rates of Tbit/s; ICs for ultrafast computer system CPUs; ICs for THz terminal equipment of defense, surveillance, and security systems; ICs for THz terminal equipment of medical and biologic imaging systems; ICs for THz terminal equipment of food control systems. Description of the Drawings

Figure 1 (A) shows a transverse cross section of an MGTL constituted by two longitudinally parallel strips or films, (2) and (3), made of an isotropic soft magnetic material; the magnetic strips or films are placed on opposite faces of an insulating slice of dielectric material, (1).

Figure 1(B) shows a perspective view of the MGTL, where the insulating slice of dielectric material (1) has been omitted for better visualization of the magnetic strips. In addition to the magnetic strips (2) and (3) already displayed in Figure 1(A), Figure 1 (B) also shows the bending of the strips at both ends of the structure, (4) and (5); the grouping (2), (3), (4) and (5) forms a closed magnetic circuit. The piece (6), embracing the bent (4), is a metallic strip at whose terminals the emitted electric signal is applied. Likewise, the piece (7), embracing the bent (5) , is a metallic strip at whose terminals the electric signal is received.

Figures 2, 3, 4 and 5 concern the Example analyzed in the next Section, where the performances of the ELTL and MGTL are compared, in the terahertz range. In Figure 2, the attenuation characteristics of both transmission lines, ELTL and MGTL, are compared; the comparison reveals the attenuation improvement resulting from choosing the MGTL in the THz range. In Figure 2(A), the vertical axis AT refers to the attenuation constant in dB/mm. In Figure 2 (B) , the vertical axis ΔΑΤ refers to the difference between values of the attenuation constant in dB/mm.

In Figure 3, the phase velocity characteristics of both transmission lines, ELTL and MGTL, are compared; the comparison reveals the velocity improvement resulting from choosing the MGTL in the THz range. In Figure 3(A), the vertical axis NPV refers to the normalized phase velocity. In Figure 3(B), the vertical axis APV refers to the difference between values of the phase velocity in km/s.

In Figure 4, the group velocity characteristics of both transmission lines, ELTL and MGTL, are compared; the comparison reveals the velocity improvement resulting from choosing the MGTL in the THz range. In Figure 4(A), the vertical axis NGV refers to the normalized group velocity. In Figure 4 (B) , the vertical axis AGV refers to the difference between values of the group velocity in km/s.

In Figure 5, the dispersion characteristics of both transmission lines, ELTL and MGTL, are compared; the comparison reveals the dispersion improvement resulting from choosing the MGTL in the THz range. In Figure 5(A), the vertical axis GD refers to the group dispersion in ns/m. In Figure 5 (B) , the vertical axis AGD refers to the difference between values of the group dispersion in ps/m. Example

In this Example the transmission properties exhibited by an ELTL and an MGTL are compared. Both structures share the same geometrical configuration: two parallel metallic strips (ELTL) , two parallel magnetic strips (MGTL).. The insulating slice- of dielectric material is also the same for both transmission lines.

The width of strips (2) and (3) is 10 μπι. The thickness of the insulating slice of dielectric material (1) is 5

The electromagnetic properties of the several materials considered in the numerical simulation on which this Example is based are:

Metallic strips (ELTL) :

Conductivity: σ = 61 10⁶ S/m

Magnetic permeability: μ = μο = 4π 10^~7 H/m_.

Magnetic strips (2) and (3) (MGTL):

Conductivity: σ = 1 S/m

Magnetic permeability: μ = 10 μ₀ = 4π 10^~3 H/m

Insulating slice of dielectric material (1):

Relative permittivity: £_r = 10

Loss tangent: tan 5 = 0.5 10^"3

The wave propagation properties of a transmission line are determined by its propagation constant γ = α(ω) + ]β(ω) , where a is the attenuation constant, and β is the phase constant; both parameters depending on the angular frequency ω = 2nf, where f is the frequency (in Hz) .

The analysis carried out revealed that the MGTL performs better than the ELTL for frequencies above 2 THz.

Figure 2 displays the attenuation against frequency, for both transmission lines MGTL and ELTL. Curves in Figure 2(A) show absolute values of the attenuation constant. Figure 2(B) depicts the difference between curves. MGTL attenuation not only is smaller than ELTL attenuation, but also, it slowly varies with the frequency .

Figure 3 displays the phase velocity v_p = ω/β against frequency. Figure 3 (A) shows curves of v_p normalized to the speed of light in a vacuum v_0r for both transmission lines MGTL and ELTL. Figure 3 (B) depicts the difference between absolute values of the phase velocity. MGTL phase velocity not only is higher than ELTL phase velocity, but also, it remains practically frequency-invariant and equal to v₀.

Figure 4 displays the group velocity v_g = άω/άβ against frequency. Figure 4 (A) shows curves of v_g normalized to the speed of light in a vacuum v₀, for both transmission lines MGTL and ELTL. Figure 4(B) depicts the difference between absolute values of the group velocity. MGTL group velocity not only is higher than ELTL group velocity, but also, it . remains practically frequency-invariant and equal to vo .

Group dispersion is related to the broadening or distortion of the signal envelope. Dispersion, G_D, expressed in s/m, is just the inverse of the group velocity, G_D = l/v_g. Its graphical, representation against frequency is depicted in Figure 5. Curves in Figure 5 (A) represent absolute values of the dispersion, for both transmission lines MGTL and ELTL. Figure 5(B) shows the difference between the two curves. MGTL dispersion not only is smaller than ELTL dispersion but, also, it slowly varies with the frequency.

The said device is to be used in integrated circuits (ICs) that are part of terminal equipment for use in terahertz technology, namely: ICs for terminal equipment of advanced telecommunication systems with bit rates of Tbit/s; ICs for ultrafast computer system CPUs; ICs for THz terminal equipment of defense, surveillance and security systems; ICs for THz terminal equipment of medical and biologic imaging systems; ICs for THz terminal equipment of food control systems. References

- IEEE Transactions on Terahertz Science and Technology, Vol. 1, No. 1, pp. 9-331, Sept. 2011.

- M. Wanke, M Lee, "The Terahertz Frontier", IEEE Spectrum, Vol. 48, No. 9, pp. 38-43, Sept. 2011.

- K. Humphreys, J. Loughran, M. Gradziel, T. Ward, J. Murphy, C. 0' Sullivan, "Medical Applications of Terahertz Imaging: A Review of Current Technology and Potential Applications in Biomedical Engineering," Proc. 26^th Annual Int. Conference of the IEEE EMBS, pp. 1302-1305. San Francisco, Sept. 2004.

- Z. Yan, Y. Ying, H. Zhang, H. Yu, "Research. Progress of Terahertz Wave Technology in Food Inspection," Proc. of SPIE, Vol. 6373, pp. 63730R1-63730R10, Oct. 2006.

Claims

Magnetic transmission line device of electromagnetic signals characterized in that it comprises a structure that includes an insulating slice, of dielectric material, (1), in whose opposite faces two longitudinally parallel strips made of an isotropic soft magnetic material, (2) and (3), are deposited, the strips are bent at both ends, (4) and (5), and are externally coupled via two metallic strips (6) and ( 7 ) .

Use of the device, identified in claim 1, characterized in that it is applied in the following THz technological areas : a) ICs for terminal equipment of advanced telecommunication systems with bit rates of Tbit/s;

b) ICs for ultrafast computer system CPUs;

c) ICs for THz terminal equipment of defense, surveillance, and security systems;

d) ICs for THz terminal equipment of medical and biologic imaging systems;

e) ICs for THz terminal equipment of food control systems.