WO2005062414A1 - Impedance terminale a couche mince - Google Patents

Impedance terminale a couche mince Download PDF

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Publication number
WO2005062414A1
WO2005062414A1 PCT/AU2004/001823 AU2004001823W WO2005062414A1 WO 2005062414 A1 WO2005062414 A1 WO 2005062414A1 AU 2004001823 W AU2004001823 W AU 2004001823W WO 2005062414 A1 WO2005062414 A1 WO 2005062414A1
Authority
WO
WIPO (PCT)
Prior art keywords
transmission line
impedance
termination
segment
planar transmission
Prior art date
Application number
PCT/AU2004/001823
Other languages
English (en)
Other versions
WO2005062414A8 (fr
Inventor
Leonard Thomas Hall
Derek Abbott
Original Assignee
Adelaide Research & Innovation Pty Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from AU2003907133A external-priority patent/AU2003907133A0/en
Application filed by Adelaide Research & Innovation Pty Ltd filed Critical Adelaide Research & Innovation Pty Ltd
Publication of WO2005062414A1 publication Critical patent/WO2005062414A1/fr
Publication of WO2005062414A8 publication Critical patent/WO2005062414A8/fr

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00—Auxiliary devices
    • H01P1/24—Terminating devices
    • H01P1/26—Dissipative terminations
    • H01P1/268—Strip line terminations
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/0213—Electrical arrangements not otherwise provided for
    • H05K1/0237—High frequency adaptations
    • H05K1/0246—Termination of transmission lines
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/16—Printed circuits incorporating printed electric components, e.g. printed resistor, capacitor, inductor
    • H05K1/167—Printed circuits incorporating printed electric components, e.g. printed resistor, capacitor, inductor incorporating printed resistors
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/0213—Electrical arrangements not otherwise provided for
    • H05K1/0216—Reduction of cross-talk, noise or electromagnetic interference
    • H05K1/023—Reduction of cross-talk, noise or electromagnetic interference using auxiliary mounted passive components or auxiliary substances
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/0213—Electrical arrangements not otherwise provided for
    • H05K1/0237—High frequency adaptations
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/03—Conductive materials
    • H05K2201/0302—Properties and characteristics in general
    • H05K2201/0317—Thin film conductor layer; Thin film passive component

Definitions

  • This invention relates to planar transmission lines and terminating these lines with a suitable impedance.
  • Transmission lines are used in radio frequency applications to propagate energy in the form of electromagnetic signals from one point to another.
  • Transmission lines may take on many forms ranging from coaxial cables to planar transmission lines which consist of a pair of parallel strips disposed on a dielectric substrate.
  • thin film resistors are very commonly used to terminate the line by placing them between the line being terminated, and a short circuit.
  • Particular materials are used to provide the thin film impedance, with the impedance of the film being defined in ⁇ per square. Any sized square of material will have identical impedance.
  • the effective impedance of the thin film resistor used may be varied by varying the width to length ratio of the resistor used. For example, two square films each having an impedance of 50 ⁇ per square, placed one after the other, will result in an impedance of 100 ⁇ . This is because the two squares, each of 50 ⁇ per square are effectively placed in series with each other.
  • any desired impedance can be provided by varying the ratio of length to width of the square films being used. This is of course assuming a linear current distribution.
  • the linear current distribution assumption starts to break down.
  • the impedance film begins to behave as a lossy microstrip transmission line.
  • the impedance being used should be terminated in a short circuit. At low frequencies, this can be achieved by using a via to connect the impedance to ground.
  • the via is created by cutting a hole in the substrate and through the impedance and filling the hole with a conductor. At higher frequencies however, the via is no longer suitable because it starts to act as an inductor rather than as a short circuit, reducing the effectiveness of the match.
  • a termination for a planar transmission line wherein the termination comprises a thin lossy material terminated in an open circuit.
  • a method of terminating a planar transmission line comprising: terminating the planar transmission line with a thin lossy material terminated in an open circuit.
  • a method of terminating a planar transmission line comprising: shaping a segment of thin lossy material so that in use, the material will provide an ac path to ground as well as an impedance match for the planar transmission line; and terminating the planar transmission line with the shaped segment of thin lossy material, itself terminated with an open circuit.
  • a thin film termination segment shaped according to the methods of the second and/ or third aspects of the present invention.
  • Figure 1 shows an arrangement of a transmission line matched with a thin film impedance
  • Figure 2 shows a representation of a lossy transmission line
  • Figure 3 shows simulated and analytically predicted voltage reflection factor variation with frequency assuming an open circuit termination of infinite impedance
  • Figure 4 shows simulated and analytically predicted impedance variation with frequency assuming an open circuit termination of infinite impedance
  • Figure 5 shows the predicted voltage reflection factor as the dimensions of the thin film are optimised
  • Figure 6 shows the simulated impedance variation with frequency of an open circuit termination
  • Figure 7 shows the simulated and analytically predicted voltage reflection factor variation with frequency using an open circuit termination as shown in figure 6
  • Figure 8 shows the simulated and analytically predicted impedance variation with frequency using an open circuit termination as shown in figure 6
  • Figure 9 shows the predicted voltage reflection factor as the dimensions of the thin film are optimised, using an open circuit termination shown in figure 6
  • Figure 10 shows comparisons in the measured, simulated and analytically predicted performance of a load designed according to the present invention using manual iteration.
  • FIG. 1 A typical arrangement of a planar transmission line 10 terminated by thin film impedance 20 according to the present invention is shown in Figure 1. This arrangement is, starkly different to prior arrangements as prior arrangements require the use of a via or a quarter wave transformer connected to the end distal to the transmission line.
  • Thin film impedance 20 is disposed at the end of transmission line 10 to match the inherent or characteristic impedance of transmission line 10 such that there is no energy reflected from the termination of transmission line 10, thus maximising power transfer from a source (not shown) to a load termination.
  • Thin film impedance square 20 is made from a known material which has a known inherent or characteristic impedance measured in Ohms per square. The actual impedance of the thin film will be determined by the ratio of the length 21 to the width 22 of the rectangle. If this ratio is equal to 1, then the impedance of the film will be equal to the characteristic impedance per square. For example, if the characteristic impedance of the film is 25 ⁇ , then a square of that material will provide an impedance of 25 ⁇ .
  • w is the width of the thin film impedance
  • R A_ and R TH i s W the thin film impedance in Ohms per Square.
  • this line would normally be expected to be terminated by a thin film resistive load, followed by a short circuit in the form of a via or transformer.
  • this arrangement can be completely replaced by a termination consisting entirely of the thin film resistive load itself terminated by an open circuit. This is accomplished by appropriately shaping or sizing the thin film resistor so that it acts as the transformer to ac ground and resistive load, as a single entity.
  • the present invention provides an impedance transformer with distributed resistance. This amounts to taking a lossless transmission line and deliberately terminating it with a short segment of lossy line that has one end unconnected, this being completely contradictory to current practice and theory. This lossy segment is realised in the preferred embodiment, by standard thin film resistive material.
  • Z is the impedance of the load.
  • tanh(iY) tanh(l ⁇ /) + jtan(j ⁇ ') 1 + jtanh(l ⁇ /)tan(j ⁇ ')
  • the thin film sheet resistance of the lossy segment needs to be 77.71 ⁇ /D.
  • the lossy line segment is designed to be a third of the stripline width - by following the same procedure we find that we would need a thin film sheet resistance of 55.03 ⁇ /D.
  • the actual centre frequency fo is affected by the length 21 of strip 20.
  • the length 21 of strip 20 will be in the order of a quarter wavelength of the signal being propagated along transmission line 10.
  • the length 21 of strip 20 will not be precisely a quarter wavelength as will be understood by the person skilled in the art.
  • Ohmega-Ply which is a thin Nickel Phosphorous (N:P) alloy, electrodeposited onto R5880 Duroid, as a substrate.
  • figure 10 shows a comparison between the predicted, simulated and measured results of the performance of a load designed according to the present invention, using manual iteration.
  • the present invention thus effectively provides a combined thin film resistive termination and a transformer into the single termination structure. This results in a reduced space requirement; reduces the number of metal track to thin film resistor connections (thus also improving reliability and increasing manufacturing efficiency), and provides for good matching over a wider bandwidth.
  • the resulting monointentionally lossy impedance transformer or a transformer with lithic combined transfo ⁇ ner and load takes up distributed load resistance.
  • the advantage of this new structure is less space and this is an important consideration in microstrip in its simplicity, compactness and more importantly in its higher bandwidth performance over existing methods. designs with the push toward compact portable systems and higher frequencies.
  • Use of this new form of termination is also Index Terms — Impedance transformers, Impedance matching, advantageous as it removes the need for the via in a system Microstrip components, Planar transmission lines, Planar waveguides. and also provides good matching over a wider bandwidth as opposed to the narrower bandwidth traditionally offered using vias [15]. Moreover, this implies removal of a dc path to I.
  • Fig. 1 Layout of matched termination/transformer.
  • the lossless microstrip line is shown on the left and the thin film resistor termination is shown in matched termination at the end of a given microstrip line.
  • Our black to the right Notice that there is no via or quarter wavelength line to proposed method can be used to terminate both microstrip the right of the resistor, acting as a short circuit Instead, the resistor itself lines, in the above mentioned applications, as well as for acts as the transformer.
  • the black colored region can be thought of as an impedance transformer with distributed resistance.
  • the length of this region termination of dummy ports on printed lens structures such is I and the width is w. as those in [11]— [14].
  • the microstrip line with our new termination, can be matched termination for microstrip and stripline applications.
  • the matching structure is easy to design, low-cost, compact transmission line.
  • a lossy transmission line is represented by and convenient to manufacture making it extremely useful in a large number of identical segments each made up of very high frequency electromagnetic circuits.
  • the layout of this new termination structure is shown in width w in series with a small resistance AR as shown in Figure 1 and is realized using a thin film resistor. What is Figure 2.
  • ⁇ is the wavelength in the thin film in predicting the open circuit impedance at the end of the transmission line and I is the length and w is the width of transmission line and the difficulty in accurately predicting the thin film transmission line. From this starting point the the wavelength in microstrip lines. dimensions of the impedance were easily optimized. A simple iterative procedure was to vary the length of the termination, whilst keeping the predicted impedance real, and to increase the width to reduce the magnitude of the impedance. Then, as the predicted impedance became progressively closer to the required impedance, the iteration step size was made progressively smaller until a satisfactory impedance match was found.
  • FIG. 3 This figure depicts a 50 ⁇ coax to microstrip transition followed by Fig. 5.
  • This graph shows that the results simulated by Ensemble and a traditional quarter wavelength transformer to 2 5 ⁇ then terminated with HFSS closely resemble the measured results.
  • the performance of this device is This demonstrates the need for final optimisation using a full-wave software shown in Figure 5.
  • the substrate used was RT-Duroid 5880 with a thickness simulation tool. of 0.762 mm and the thin film termination is made from electro-deposited Nickel-Phosphorous (NiP) alloy.
  • Rao Design of Rotman lens feed network to generate a hexagonal lattice of multiple beams
  • L. T. Hall, H. Hansen, and D. Abbott "Rotman lens for mm- wavelengths," in Proc. SPIE Smart Structures, Devices and Systems,

Landscapes

  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
  • Non-Reversible Transmitting Devices (AREA)

Abstract

La présente invention concerne un procédé et un appareil pour terminer une ligne de transmission plane sans utiliser de trou de liaison ou de transformateur d'impédance. Selon cette invention, la terminaison d'une ligne de transmission plane est assurée par un segment de terminaison à couche mince qui se termine lui-même dans un circuit ouvert et qui est conçu pour correspondre de manière efficace à l'impédance de la ligne de transmission. Cette invention est utilisée pour assurer la terminaison d'une vaste gamme de lignes de transmission planes et permet de réduire la complexité et les coûts par rapport aux procédés de l'état antérieur de la technique.
PCT/AU2004/001823 2003-12-24 2004-12-24 Impedance terminale a couche mince WO2005062414A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AU2003907133A AU2003907133A0 (en) 2003-12-24 Thin film impedance termination
AU2003907133 2003-12-24

Publications (2)

Publication Number Publication Date
WO2005062414A1 true WO2005062414A1 (fr) 2005-07-07
WO2005062414A8 WO2005062414A8 (fr) 2005-10-06

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/AU2004/001823 WO2005062414A1 (fr) 2003-12-24 2004-12-24 Impedance terminale a couche mince

Country Status (1)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4210885A (en) * 1978-06-30 1980-07-01 International Business Machines Corporation Thin film lossy line for preventing reflections in microcircuit chip package interconnections
JPS61173502A (ja) * 1985-01-28 1986-08-05 Mitsubishi Electric Corp 無反射終端装置
US6593829B2 (en) * 2001-09-06 2003-07-15 Anritsu Company Microstrip dot termination usable with optical modulators
US6600384B2 (en) * 2001-05-18 2003-07-29 Endwave Corporation Impedance-compensating circuit
US6660174B2 (en) * 2001-09-21 2003-12-09 Anritsu Company Method of manufacturing a microstrip edge ground termination
US20040119551A1 (en) * 2002-12-20 2004-06-24 Com Dev Ltd. Transmission line termination

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4210885A (en) * 1978-06-30 1980-07-01 International Business Machines Corporation Thin film lossy line for preventing reflections in microcircuit chip package interconnections
JPS61173502A (ja) * 1985-01-28 1986-08-05 Mitsubishi Electric Corp 無反射終端装置
US6600384B2 (en) * 2001-05-18 2003-07-29 Endwave Corporation Impedance-compensating circuit
US6593829B2 (en) * 2001-09-06 2003-07-15 Anritsu Company Microstrip dot termination usable with optical modulators
US6660174B2 (en) * 2001-09-21 2003-12-09 Anritsu Company Method of manufacturing a microstrip edge ground termination
US20040119551A1 (en) * 2002-12-20 2004-06-24 Com Dev Ltd. Transmission line termination

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN *

Also Published As

Publication number Publication date
WO2005062414A8 (fr) 2005-10-06

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