US3768044A - Passive limiter for high-frequency waves - Google Patents

Passive limiter for high-frequency waves Download PDF

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Publication number
US3768044A
US3768044A US00240743A US3768044DA US3768044A US 3768044 A US3768044 A US 3768044A US 00240743 A US00240743 A US 00240743A US 3768044D A US3768044D A US 3768044DA US 3768044 A US3768044 A US 3768044A
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Prior art keywords
diode
diodes
waveguide
end wall
channel
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Expired - Lifetime
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US00240743A
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English (en)
Inventor
R Henry
G Sillard
P Blanchard
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Thales SA
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Thomson CSF SA
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G11/00—Limiting amplitude; Limiting rate of change of amplitude
    • H03G11/02—Limiting amplitude; Limiting rate of change of amplitude by means of diodes
    • H03G11/025—Limiting amplitude; Limiting rate of change of amplitude by means of diodes in circuits having distributed constants
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/03—Details of HF subsystems specially adapted therefor, e.g. common to transmitter and receiver
    • G01S7/034—Duplexers

Definitions

  • ABSTRACT designed to block transmission of high-amplitude pulses over a signal path such as a duplexing channel of a radar transceiver, comprises two or more pairs of diodes connected in antiparallel relationship between ground and a common point on the transmission channel.
  • Each diode consists of three semiconductor layers, i.e. two heavily doped outer layers N P and a lightly doped intermediate layer N or P.
  • Each diode is enclosed in a thermally conductive housing with two spaced-apart end walls receiving the semiconductive wafer therebetween, the wafer resting on one end wall and being tied to the opposite end wallby one or more leads leaving a large void inside a dielectric shell of, for example, beryllium oxide.
  • TR tubes which are inserted between two couplers of the 3-dB type in a shunt path and, in response to voltages surpassing their breakdown potential, fire to establish an effective short circuit which reflects the incoming waves. While these tubes operate generally satisfactorily, they have a limited service life which after a while allows the transmitted voltages to attain excessive levels detrimental to the'receiver. Another drawback of these tubes is their delayed firing which, lets part of the incoming wave energy reach the receiver with possible harmful consequences.
  • the general object of our invention is to provide a limiter of this character which avoids the aforestated drawbacks and, while being highly discriminative between high and low voltages, causes sharp attenuation of the former while permitting transmission of the latter without significant loss.
  • our invention aims at providing a passive limiter capable of absorbing high-frequency power peaks on the order of several kW, with an average power exceeding 100 watts, while decoupling the signal source from the load with an attenuation upward of 40 dB.
  • each diode comprises a stack of semiconductive layers (preferably of silicon) including two relativelyheavily doped outlet layers of opposite conductivity types, hereinafter designated P and N*, and a relatively lightly doped intermediate layer of one conductivity type, designated P or N.
  • P and N* two relativelyheavily doped outlet layers of opposite conductivity types
  • P or N a relatively lightly doped intermediate layer of one conductivity type
  • break-down threshold may be raised by cascading two or more diodes of the same conductivity type, whereas protection over a wider frequency band may necessitate the use of several diode pairs spaced along the transmission channel.
  • each diode or possibly of several stacked diodes
  • a thermally conductive housing facilitating the dissipation of the generated heat.
  • a housing advantageously includes two electrically conductive end walls, one of them supporting the wafer constituted by the semiconductive layers while the other is held spaced therefrom by a surrounding wall of dielectric and highly heat-conductive material, such as beryllium oxide (BeO).
  • BeO beryllium oxide
  • one of the end walls of each diode housing maybe anode or cathode lead.
  • the diodes may be mounted within the guide structure to which they may be electrically connected with the aid of an intermediate conductive body tied to a neutral point of the structure.
  • FIG. 1 is a diagrammatic view of a voltage-limiting diode corresponding to our invention
  • FIGS. 2 and 3 are elevational views, partly in section, of two modes of mounting such a diode in a housing;
  • FIG. 4 is afragmentary circuit diagram showing a pair of such diodes connected to a signal channel
  • FIG. 5 is a graph showing the current. flow through the diode of FIG. 1;
  • FIG. 6. is an equivalent circuit diagram for a limiting diode in a transmitting circuit
  • FIG. 7 is a graph showing the current flow through a pair of' diodes as illustrated in FIG..4;
  • FIG. 8 is a sectional view of an assembly including pair of diodes with housings as shown in FIGS. 2 and 3;
  • FIG. 12 is a diagrammatic perspective view of a waveguide incorporating a protective network with two diodes according to our invention.
  • FIG. 13 is a view similar to FIG. 4, showing two sets. of multiple diodes, I
  • FIG. 14 is a circuit diagram of a duplexer including a pair of limiters according to the invention.
  • FIGS. 15 and16 are diagrams similar to FIG. 14, showing different diode combinations included in the limiters of the latter Figure. i
  • FIG. 1 we have shown a conductive base 1 serving as a cathode connection for a diode in the form a wafer 5 of semiconductive material, specifically .silicon,
  • Bottom layer 2 is of the type N* and may have a thickness on the order of 60 microns.
  • Intermediate layer 3 is of type N and is considerably thinner than layer 2 which it partly overlies.
  • Top layer 4, coextensive with layer 3, is still thinner than the latter end of type 1.
  • FIG. 2 shows the wafer inside a housing whose lower part forms an electroconductive end wall integral with cathode l.
  • the top layer 4 (FIG. 1) of wafer 5 is connected by wires 9 to an opposite end wall 7 of similar conductive material constituting the anode of the diode assembly.
  • the two conductive members 7 and 10 are separated by a peripheral wall 8 of dielectric but highly heat-conductuve material such as BeO.
  • the entire unit has been designated 11.
  • a similar unit 12, illustrated in FIG. 3, has the same basic construction except that wafer 5 is now mounted on the top wall serving as a cathode 1; anode 7 is integral with the bottom part 10 of the unit.
  • FIGS. 2 and 3 Two units as shown in FIGS. 2 and 3, if connected to a common junction point at corresponding ends (e.g. at the top) and grounded at their opposite ends as illustrated, form an antiparallel pair (see FIG. 4) responsive to voltages of. opposite polarities.
  • a similar pair can be made up from two identical units 11 or 12 if their conductivity types are relatively inverted, as by making the layers 2, 3 and 4 of FIG. 1 of type P P and N respectively.
  • the embodiments described with reference to these diode combinations could'be interchangeably employed.
  • two such units 11 and 12 are connected in a pair of parallel paths but with relatively inverted polarities (a relationship termed antiparallel") between ground and a junction point 6 on a line 13 which may be a strip conductor as more fully illustrated in FIG. 8.
  • These diodes are virtually nonconductive for low signal voltages of high frequency passing along the channel 13; in the presence of higher voltages surpassing their forward threshold potential V; (FIG. 5), however, the diode of theproper polarity breaks down and becomes a short circuit, causing the incoming wave to be reflected toward its origin.
  • the potential V, illustrated in FIG. 5 may be on the I order of 1 V and corresponds to the voltage drop across the forbidden band of the semiconductive material (silicon).
  • a diode as described with reference to FIG. 1 may sustain a peak'power on the order of 1.3 kW and voltage peaks of about 720 V.
  • Its equivalent circuit, shown in FIG. 6, comprises a shunt resistance R, across a signalsource '15 working into a line resistance 16 (e.g. of ohms); shunt resistance R, includes such parasitic impedan'ces as the capacitance of the diode housing and the inductivity of the leads 9.
  • V sincot where o) is the pulsatance of a radar frequency of about 3 GHz. This corresponds to a cycle length T (FIG. 5) of about 0.33 ns, which is a small fraction of the recombination period of the minority and majority charge carriers (on the order of I00 ns) injected into the diode by the impressed signal voltage. It may be assumed that the first half-cycle of any incoming signal lies below the break-down potential V; so that the diode does not conduct and the carriers are swept out at the next halfcycle. Upon a subsequent rise of the voltage V beyond the forward threshold V,, however, e.g.
  • the total diode current composed of phases I, (forward) and I,- (reverse), is zero from the instant t O to the time t t when the diode ceases to conduct.
  • the diode voltage V, V sinwt, at the instant of blocking can be calculated by integration from O to T/2 and from T/2 to T, with V, V, In the specific case here considered, V, equals about 95 V.
  • the disclosed arrangement prevents the appearance of detrimental voltage peaks inasmuch as the sweepout time for the charge carriers'of one diode equals the injection time for the other diode.
  • the terminal voltageof the forwardly driven diode is substantially limited to V) as the flooding of its intermediate layer with charge carriers makes its break-down resistance R, extremely low.
  • the conductive housing portions of the two units 11 and 12 contact a conductor strip 13 from opposite sides, the strip being sandwichedbetween two.
  • grounded conductor shields 17 and 18 with interposition of insulating members 39, 40 surrounding these units with clearance.
  • Shields 17, 18 are perforated to receive two cylindrical sleeves 21, 22 with threaded bushings 41, 42 accommodating respective inserts 19 and 20 which in turn hold the units 11 and 12..
  • a loop ST extends from central conductor 13 to groundon member 17 so as to act as aninductance resonating the leakage capacitance C, (FIG. 10) of the diode housings at the'operating frequency.
  • the junction capacitance C, of the diodes at applied zero voltage may range between 0.4 and 0.55 pF. In a frequency band of 2,450 to 2,500
  • a protective network may also comprise two limiter stages 23, 24 each including a pair of units 1 l and 12 connected in antiparallel relationship as defined above, their junction points 6, 6' being spaced by a'quarter wavelength (M4) of the oscillations emitted by source 15.
  • Channel 13 may again be a strip conductor of the type illustrated in FIG. 8.
  • the presence of the second stage 24, downstream of stage 23, provides improved low-level impedance matching, increases the operative bandwidth and accordingly allows a greater margin for deviations of the units from a predetermined standard. With proper matching the low-level losses are still small, e.g. of about 0.6 dB.
  • the large zero-level resistance R is replaced by the small shunt resistance R, in series with the internal inductance L,; the parasitic reactances C, and ST may be ignored in this situation.
  • the attenuation of the reflected wave, due primarily to the upstream diode pair 23, is on the order of 0.3 dB.
  • FIG. 12 illustrates the possibility of employing our protective diodes in a waveguide 25 serving as a transmission channel for microwaves to be selectively attentuated.
  • two three-layer diodes 26, 27 may be mounted without thermally conductive enclosures in the electric plane (vector E) of the rectangular guide, between opposite walls thereof and confronting surfaces of a conductive insert 28 of brass or the like which in turn is tied by conductors 29, 30 to the neutral midpoints on the two other guide walls.
  • the broad bases (1, FIG. 1) of the diodes may rest directly on the top and bottom walls of the waveguide while their exposed layers (4) bear upon the body 28, the two diodes being of the same conductivity type but opposite orientation relative to field E.
  • FIG. 13 illustrates the possibility of cascading several diodes ll, 12 in two antiparallel stacks between ground and the junction point 6 on channel 13. This arrangement enables the absorption of still greater signal powers but calls for more intensive cooling.
  • FIG. 14 we have illustrated a duplexer for a radar station including a transceiving antenna 33, a transmitter 34, a dummy load 35 and a receiver 36 conventionally interconnected by channels 43, 44 with the aid of two 3-dB couplers 31, 32 in tandem with each other. Between these couplers, each channel is provided with a limiter according to our invention designated 37 and 38, respectively. As shown in FIG. 15, each of these limiters is of the two-unit type illustrated in FIG. 4; FIG. 16 shows an arrangement as discussed with reference to FIG. 9, i.e. two pairs of diodes spaced a quarter wavelength apart. A tested embodiment of the system of FIG.
  • the attenuation of strong signals from nearby transmitters was established at approximately 25 dB for the system of FIG. 15 and at roughly that for the pulses from the associated transmitter 34 (i.e. better than 47 dB) with the system of FIG. 16.
  • the performance especially of the simpler system according to FIG. 15 could, if desired, be further improved by the insertion of a supplemental passive limiter of low attenuation level (eg about 15 dB) in the high-frequency stage of the radar receiver 36.
  • a protective structure for a signal channel carrying high-frequency electromagnetic waves comprising:
  • a pair of alignedly juxtaposed heat-dissipative housings each including two spaced-apart electrically conductive first and second end walls and a dielectric peripheral wall of high thermal conductivity surrounding the space between said end walls, the first end wall of one housing being physically and conductively secured to the first end wall of the other housing;
  • mounting means physically and conductively secured to said housings by their second end walls, said mounting means forming a clearance aboutsaid housings;
  • a voltage-limiting semiconductive diode in each of said housings physically supported on.one end wall thereof and provided with a conductive connection to the opposite end wall; and A circuit means connecting said channel between said mounting means and said first end wall of each housing.
  • each diode comprises a semiconductive wafer supported on said one end wall of the associated housing in spaced relationship with said opposite end wall, said conductive connection including wire means extending from said wafer to said opposite end wall.
  • each of said diodes comprises a stack of semiconductive layers including two relatively heavily doped outer layers of opposite conductivity types and a lightly doped intermediate layer of one conductivity type.
  • a pair of voltage-limiting semiconductive diodes disposed in the electric plane of said waveguide, said diodes being connected with relatively inverted polarity between the other two walls of said waveguide and confronting surfaces of said body.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Tone Control, Compression And Expansion, Limiting Amplitude (AREA)
  • Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
US00240743A 1971-04-09 1972-04-03 Passive limiter for high-frequency waves Expired - Lifetime US3768044A (en)

Applications Claiming Priority (1)

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FR7112746A FR2133169A5 (enrdf_load_stackoverflow) 1971-04-09 1971-04-09

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DE (1) DE2216849C3 (enrdf_load_stackoverflow)
FR (1) FR2133169A5 (enrdf_load_stackoverflow)
GB (1) GB1382334A (enrdf_load_stackoverflow)
SE (1) SE378158B (enrdf_load_stackoverflow)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4357583A (en) * 1979-05-31 1982-11-02 Thomson-Csf Passive electromagnetic wave limiter and duplexer formed by means of such a limiter
US6130639A (en) * 1997-01-27 2000-10-10 Thomson-Csf Method for fine modelling of ground clutter received by radar
FR2796467A1 (fr) * 1999-06-29 2001-01-19 Thomson Csf Dispositif de limitation de puissance dans un recepteur
CN100536225C (zh) * 2006-11-09 2009-09-02 中国科学院电子学研究所 一种带状线型大功率微波限幅器
EP2728749A3 (de) * 2012-11-06 2018-03-14 Rohde & Schwarz GmbH & Co. KG Begrenzer für breitbandige Hochfrequenzsignale
US10573963B1 (en) 2017-09-15 2020-02-25 Hrl Laboratories, Llc Adaptive nulling metasurface retrofit
US11041936B1 (en) 2018-10-04 2021-06-22 Hrl Laboratories, Llc Autonomously reconfigurable surface for adaptive antenna nulling

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2512281B1 (enrdf_load_stackoverflow) * 1981-08-28 1983-10-28 Thomson Csf
FR2611989A1 (fr) * 1987-03-06 1988-09-09 Thomson Semiconducteurs Dispositif hyperfrequence a diodes comportant une ligne triplaque

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2835867A (en) * 1953-11-25 1958-05-20 Underwood Corp Signal attenuator
US2956160A (en) * 1957-12-18 1960-10-11 Bell Telephone Labor Inc Millimeter wave crystal rectifier
US3067394A (en) * 1960-07-22 1962-12-04 Polarad Electronics Corp Carrier wave overload protector having varactor diode resonant circuit detuned by overvoltage
US3107335A (en) * 1961-09-29 1963-10-15 Hewlett Packard Co High frequency transmission line having variable absorption using variably biased semiconductor devices shunting the line
US3196327A (en) * 1961-09-19 1965-07-20 Jr Donald C Dickson P-i-n semiconductor with improved breakdown voltage
US3202942A (en) * 1962-02-28 1965-08-24 Robert V Garver Microwave power amplitude limiter
US3226661A (en) * 1963-05-06 1965-12-28 Robert V Garver Broad band tem diode limiters
US3346825A (en) * 1965-06-28 1967-10-10 Ass Elect Ind Waveguide switch with semiconductor in thermal contact with waveguide walls
US3462654A (en) * 1966-10-05 1969-08-19 Int Rectifier Corp Electrically insulating-heat conductive mass for semiconductor wafers
US3517272A (en) * 1968-12-24 1970-06-23 Rca Corp Microwave circuit with coaxial package semiconductor device
US3571765A (en) * 1969-09-15 1971-03-23 Bell Telephone Labor Inc Quantized phase shifter utilizing open-circuited or short-circuited 3db quadrature couplers

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2959778A (en) * 1956-11-19 1960-11-08 Philco Corp Transmit-receive device
US2962584A (en) * 1957-03-07 1960-11-29 Norman Ind Inc Van Improvements in or relating to switching devices for signal transceivers
FR1348134A (fr) * 1962-02-16 1964-01-04 Siemens Ag Albis Commutateur émission-réception pour lignes symétriques et non symétriques
FR1533408A (fr) * 1967-06-08 1968-07-19 Thomson Houston Comp Francaise Perfectionnements aux dispositifs de commutation pour lignes hyperfréquences applicables notamment en microélectronique
US3538465A (en) * 1969-01-21 1970-11-03 Bell Telephone Labor Inc Strip transmission line diode switch
CH487524A (de) * 1969-05-28 1970-03-15 Zellweger Uster Ag Verfahren und Vorrichtung zur Amplitudenbegrenzung von Wechselspannungen

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2835867A (en) * 1953-11-25 1958-05-20 Underwood Corp Signal attenuator
US2956160A (en) * 1957-12-18 1960-10-11 Bell Telephone Labor Inc Millimeter wave crystal rectifier
US3067394A (en) * 1960-07-22 1962-12-04 Polarad Electronics Corp Carrier wave overload protector having varactor diode resonant circuit detuned by overvoltage
US3196327A (en) * 1961-09-19 1965-07-20 Jr Donald C Dickson P-i-n semiconductor with improved breakdown voltage
US3107335A (en) * 1961-09-29 1963-10-15 Hewlett Packard Co High frequency transmission line having variable absorption using variably biased semiconductor devices shunting the line
US3202942A (en) * 1962-02-28 1965-08-24 Robert V Garver Microwave power amplitude limiter
US3226661A (en) * 1963-05-06 1965-12-28 Robert V Garver Broad band tem diode limiters
US3346825A (en) * 1965-06-28 1967-10-10 Ass Elect Ind Waveguide switch with semiconductor in thermal contact with waveguide walls
US3462654A (en) * 1966-10-05 1969-08-19 Int Rectifier Corp Electrically insulating-heat conductive mass for semiconductor wafers
US3517272A (en) * 1968-12-24 1970-06-23 Rca Corp Microwave circuit with coaxial package semiconductor device
US3571765A (en) * 1969-09-15 1971-03-23 Bell Telephone Labor Inc Quantized phase shifter utilizing open-circuited or short-circuited 3db quadrature couplers

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Ekinge et al. A New Microwave Variable Attenuator in IEE Transactions on Microwave Theory and Techniques Sept. 1970 VOLMTT18; pp. 661 662. *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4357583A (en) * 1979-05-31 1982-11-02 Thomson-Csf Passive electromagnetic wave limiter and duplexer formed by means of such a limiter
US6130639A (en) * 1997-01-27 2000-10-10 Thomson-Csf Method for fine modelling of ground clutter received by radar
FR2796467A1 (fr) * 1999-06-29 2001-01-19 Thomson Csf Dispositif de limitation de puissance dans un recepteur
CN100536225C (zh) * 2006-11-09 2009-09-02 中国科学院电子学研究所 一种带状线型大功率微波限幅器
EP2728749A3 (de) * 2012-11-06 2018-03-14 Rohde & Schwarz GmbH & Co. KG Begrenzer für breitbandige Hochfrequenzsignale
US10573963B1 (en) 2017-09-15 2020-02-25 Hrl Laboratories, Llc Adaptive nulling metasurface retrofit
US11041936B1 (en) 2018-10-04 2021-06-22 Hrl Laboratories, Llc Autonomously reconfigurable surface for adaptive antenna nulling

Also Published As

Publication number Publication date
SE378158B (enrdf_load_stackoverflow) 1975-08-18
DE2216849C3 (de) 1975-02-13
DE2216849B2 (de) 1974-06-27
FR2133169A5 (enrdf_load_stackoverflow) 1972-11-24
GB1382334A (en) 1975-01-29
DE2216849A1 (de) 1972-11-02

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