US3761846A - Impedance-matching resistor - Google Patents

Impedance-matching resistor Download PDF

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Publication number
US3761846A
US3761846A US00139326A US3761846DA US3761846A US 3761846 A US3761846 A US 3761846A US 00139326 A US00139326 A US 00139326A US 3761846D A US3761846D A US 3761846DA US 3761846 A US3761846 A US 3761846A
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Prior art keywords
conductor
impedance
matching resistor
length
conductors
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Expired - Lifetime
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US00139326A
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English (en)
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K Tsuboi
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Iwatsu Electric Co Ltd
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Iwatsu Electric Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P5/00—Coupling devices of the waveguide type
    • H01P5/02—Coupling devices of the waveguide type with invariable factor of coupling
    • H01P5/022—Transitions between lines of the same kind and shape, but with different dimensions
    • H01P5/028—Transitions between lines of the same kind and shape, but with different dimensions between strip lines
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P5/00—Coupling devices of the waveguide type
    • H01P5/02—Coupling devices of the waveguide type with invariable factor of coupling
    • H01P5/022—Transitions between lines of the same kind and shape, but with different dimensions
    • H01P5/026—Transitions between lines of the same kind and shape, but with different dimensions between coaxial lines

Definitions

  • ABSTRACT An impedance-matching resistor connected between two transmission paths of different characteristic impedances Z and (Z Rg) by the use of a seriesimpedance Rg, in which the impedance-matching resistor is formed into a transmission line, such as a coaxial line or a strip line, and a characteristic impedance Zch of the transmission line is varied so as to meet with a condition (Z x/L 'Rg) at a medium point spaced by a distance x from the input of one of said two transmission paths, the above mentioned one of the two transmission paths having the characteristic impedance Z 5 Claims, 5 Drawing Figures IMPEDANCE-MATCHING RESISTOR This invention relates to impedance-matching resistors used in high frequency circuits.
  • An impedance-matching resistor is usually employed to connect an output of a high frequency circuit, such as a pulse generator, to a load impedance.
  • a high frequency circuit such as a pulse generator
  • An object of this invention is to provide an impedance-matchingyresistor employed for theoretically providing impedance-matching in a high frequency circuit so as to eliminate distortion ofa transmitted wave form.
  • FIG. 1 is a circuit diagram illustrating an example of a conventional pulse generator using an Esaki diode (tunnel diode);
  • FIG. 2' is a wave form of an output of the pulse generator shown in FIG. 1;
  • FIG. 3 is a schematic section illustrating an embodiment of this invention applied to a coaxial cable
  • FIGS. 4A and 4B are respectively a schematic plane view and a schematic side view, illustrating an embodiment of this invention applied to' a strip line on a printed wiring board.
  • an impedance-matching resistor Rg is usually inserted between an Esaki diode D'and a load ingpedanq e Z as in FIG. 1.
  • a high impedance source and a trigger pulse source are connected across terminals 8 and 8,.
  • a coaxial cable having acharacteristicimpedance of 50 Ohms is connected as the load impedance Z,,, a single registor of 50 Ohms is usually employed as the inserted resistor Rg. Howevensince an'impedance looking into the load impedance 2, from the pulse generator is not matched witha high impedance of the pulse generator, "overshoot La appears at a rear 'end of a pulse as shown in FIG. 2. v
  • an impedance lookinginto the load impedance 2 from two terminals of the Esakidiode D assumes values Z or (Rg Z,) if the inserted resistor Rg is equal to zero or is not equal to zero respectively;
  • the Esaki diode D and the load impedance 2 are connected to each other by a transmission line, such as a coaxial cable or a strip line etc. Accordingly, the above mentioned overshoot cannot be eliminated if impedance matching is not performed between the Esaki diode D and the load impedance Z, so that the output of the pulse generator cannot be employed for a pulse device, such as a sampling oscilloscope.
  • an impedance-matching resistor of this invention is proposed to be used for inserting between two high frequency circuits having different characteristic impedances (Z and Z +Rg).
  • an impedance-matching resistor of this invention is inserted between a Esaki diode D and an input (usually an connector) of a connection line (e.g.; a coaxial cable or a strip line).
  • the characteristic impedance of the impedance-matching resistor of this invention defines a transmission line having a characteristic impedance Zch and assumes an impedance (Rg Z at the connection-side to the Esaki diode D, while the characteristic impedance of the impedancematching resistor assumes an impedance Z, at the connection-side to the connection line.
  • an impedance looking into the connection line is equal to a characteristic impedance Zch of the impedancematching resistor at the medium point as mentioned below.
  • the impedance-matching resistor of this invention is so designed that the characteristic impedance Zch is gradually varied along the longitudinal direction of this impedance-matching resistor.
  • many types of the impedance-matching resistor can be realized in accordance with distribution types of a substance causing a series-resistance (generally a series-impedance). Examples of the impedance-matching resistor of this invention are shown in FIGS. 3, 4 and 4A. Before detailed description for the examples, theoretical principles for the characteristic impedance of the impedance-matching resistor of this invention are described below.
  • a characteristic impedance Zch of a transmission line is generally given as a value Zch V L/C, if an inductance for a unit length and a capacitance for a unit length are defined as values L and C respectively. Moreover, assuming the inductance L and the capacitance C between two conductors of a transmission line are given, the characteristic impedance Zch of the transmission line can be also obtained.
  • references a, b, u and e are defined as a diameter of an inner conductor, one half the inner diameter of an outer conductor, and a specific permeability and a specific dielectric constant of an insulator between the inner con ductor and the outer conductor respectively.
  • a strip line belongs to either two possible types which are the balanced type and the unbalanced type.
  • a characteristic impedance Zch of a strip line of the balanced type can be defined as follows if the width of the inner conductor, the thickness of the inner conductor and the space between outer conductors are respectively given as values W, t and b respectively and if a value W/(bt) is equal to or more than a value 0.35:
  • a reference d is a diameter ofa center conductor of the strip line, the section of which is equivalently deemed as a circle.
  • a characteristic impedance Zch of a strip line of the unbalanced type can be defined as follows, if the space against an outer co nductor is assumed as a value It, and if a value t is substantially equal to zero:
  • an impedance-matching resistor Rg is inserted between a diode D and a connector CT connected to a coaxial cable or a strip line. It is deemed that the diode D is connected, at the input of the impedance-matching resistor Rg, to a coaxial cable having a ratio a/b defined by the following relationship:
  • An impedance-matching resistor Rg of this invention is inserted between two center conductors in the generality of cases.
  • R respective impedances looked into the load Z, from each division point can be indicated by values (R 2,), (R Z ..
  • respective values b /a b /a of a ratio b/a of respective diameters of the inner and outer conductors at each division point can be determined so as to meet with the following relationship:
  • the whole outside pattern of the impedancematching resistor can be corrected under the above 7 conditions.
  • an outside pattern 2 of the impedancematching resistor shown in FIG. 3 can be obtained by calculating the value bx in response to the value x varied in a region from zero to the value L.
  • a pattern of the width W is determined as shown in FIG. 4A so as to meet with the following relationship:
  • the width W is varied along a logarithmic curve if the value b is constant.
  • equations obtained by replacing the left side Zch of equations (2), (3) and (4) by a value (Z Rg-x/L) are also satisfied. Accordingly, a required impedance-matching can be performed by adjusting the width W, the thickness 1, and the distance h against the outer conductor (Le; a metal ground plate), and moreover the space b between the outer conductors for the balanced type only.
  • an embodiment of this invention comprises an insulating board 3 usually used for printed wiring, a resistive film 1 printed or evaporatively deposited on the insulating board 3, a diode D connected to a conductor 5 on the highimpedance side of the resistive film l, a metal terminal 4 connected to another end of the resistive film l, and a metal ground plate 6 spaced by a space h from the insulating board 3.
  • an impedance-matching resistor of this invention is suitable for impedance-matching two transmission paths of different impedances and useful for reliably transmitting pulses without distortion.
  • An impedance matching resistor comprising a transmission line of predetermined length L, having an axial portion comprising one end having a characteristic impedance Z and another axial portion integral with the first-mentioned portion comprising the opposite end and having a characteristic impedance (Z +R,) to jointly define a relationship, (Z,,+xR,/L) defining a characteristic impedance at a point it along a length L of said length of transmission line.
  • An impedance matching resistor comprising a first conductor of predetermined length comprising a material having a constant resistance per unit length and a second conductor, said conductors having a configuration wherein the ratio of the transverse dimensions of said conductors at any point along the length thereof defines an exponential function, thereby jointly defining a transmission line having a linear characteristic series impedance variation linear in both directions along the length thereof, and each of said conductors having means for connecting alternatively thereto a bidirectional input and output.
  • said second conductor has a uniform width and wherein said first conductor has a configuration whereby the ratio of the transverse dimension second conductor and the transverse dimension of said first conductor define an exponential function.

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US00139326A 1970-05-04 1971-05-03 Impedance-matching resistor Expired - Lifetime US3761846A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP45037458A JPS5132946B1 (de) 1970-05-04 1970-05-04

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JP (1) JPS5132946B1 (de)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3916354A (en) * 1973-10-20 1975-10-28 Iwatsu Electric Co Ltd Attenuator for a wide range of frequencies
US4267531A (en) * 1976-08-03 1981-05-12 Georg Spinner High-frequency terminating impedance
US4413241A (en) * 1980-07-11 1983-11-01 Thomson-Csf Termination device for an ultra-high frequency transmission line with a minimum standing wave ratio
US4802178A (en) * 1986-04-10 1989-01-31 Ortel Corporation High speed fiberoptic laser module
EP0323011A2 (de) * 1987-12-18 1989-07-05 Amtech Technology Corporation Antenne mit Antwortgerät
US5656873A (en) * 1996-02-07 1997-08-12 The United States Of America As Represented By The Secretary Of The Air Force Transmission line charging
US5841342A (en) * 1995-10-13 1998-11-24 Com Dev Ltd. Voltage controlled superconducting microwave switch and method of operation thereof

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2399645A (en) * 1942-01-09 1946-05-07 Hartford Nat Bank & Trust Co High-frequency resistance
US2438915A (en) * 1943-07-30 1948-04-06 Sperry Corp High-frequency terminating impedance
US2552707A (en) * 1946-08-21 1951-05-15 Bird Electronic Corp High-frequency coaxial coupling device
US3450902A (en) * 1966-03-21 1969-06-17 Hewlett Packard Co Structure for reducing mismatch between symmetrical and asymmetrical transmission line and fast rise time generator utilizing same
US3452302A (en) * 1967-01-09 1969-06-24 Western Electric Co Coupling of dielectric to metallic waveguides

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2399645A (en) * 1942-01-09 1946-05-07 Hartford Nat Bank & Trust Co High-frequency resistance
US2438915A (en) * 1943-07-30 1948-04-06 Sperry Corp High-frequency terminating impedance
US2552707A (en) * 1946-08-21 1951-05-15 Bird Electronic Corp High-frequency coaxial coupling device
US3450902A (en) * 1966-03-21 1969-06-17 Hewlett Packard Co Structure for reducing mismatch between symmetrical and asymmetrical transmission line and fast rise time generator utilizing same
US3452302A (en) * 1967-01-09 1969-06-24 Western Electric Co Coupling of dielectric to metallic waveguides

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3916354A (en) * 1973-10-20 1975-10-28 Iwatsu Electric Co Ltd Attenuator for a wide range of frequencies
US4267531A (en) * 1976-08-03 1981-05-12 Georg Spinner High-frequency terminating impedance
US4413241A (en) * 1980-07-11 1983-11-01 Thomson-Csf Termination device for an ultra-high frequency transmission line with a minimum standing wave ratio
US4802178A (en) * 1986-04-10 1989-01-31 Ortel Corporation High speed fiberoptic laser module
EP0323011A2 (de) * 1987-12-18 1989-07-05 Amtech Technology Corporation Antenne mit Antwortgerät
EP0323011A3 (de) * 1987-12-18 1989-11-15 Amtech Technology Corporation Antenne mit Antwortgerät
US5841342A (en) * 1995-10-13 1998-11-24 Com Dev Ltd. Voltage controlled superconducting microwave switch and method of operation thereof
US5656873A (en) * 1996-02-07 1997-08-12 The United States Of America As Represented By The Secretary Of The Air Force Transmission line charging

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JPS5132946B1 (de) 1976-09-16

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