Europaisches Patentamt 094 765 • J) European Patent Office Publication number: 0 B1 Office europeen des brevets

EUROPEAN PATENT SPECIFICATION

Date of publication of patent specification: 03.05.89 Intel.4: H 03 K 3/335, H 03 K 3/33

Application number: 83302521.6

Date of filing: 05.05.83

(54) Short pulse generator.

Priority: 17.05.82 US 378558 Proprietor: SPERRY CORPORATION 1290, Avenue of the Americas New York, N.Y. 10019 (US) (§) Date of publication of application : 23.1 1.83 Bulletin 83/47 Inventor: Rao, Basrur Rama 60 Allen Street Publication of the grant of the patent: Lexington Massachusetts 02173 (US) 03.05.89 Bulletin 89/18 Representative: Singleton, Jeffrey Designated Contracting States: ERIC POTTER & CLARKSON 27 South Street DEFRGBITNL Reading Berkshire, RG1 4QU (GB)

References cited: US-A-3 832568 US-A-3 997 843 ELECTRONIC DESIGN, vol. 16, no. 6, 14th March 1968, pages 202-209, Rochelle Park, US; GQ W.B. MITCHELL: "Avalanche transistors give fast pulses" ID <0

O> O from the of the mention of the grant of the European patent, any person may o Note: Within nine months publication give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1 ) European patent convention). LU Courier Press, Leamington Spa, England. EP 0 094 765 B1 Description US — A — 3,997,843 discloses a monocycle pulse generator employing an open delay line as a The present invention pertains to the field of pulse shaper. short pulse generators. The present invention is defined in the Early prior art short pulse generators utilised a 5 appended claims and a solid state generator for mercury relay switch to discharge a transmission providing a high voltage, subnanosecond rise line which had been charged to a high voltage time pulse of substantially nanosecond duration through a long time constant. This technique is in accordance with the principles of the present capable of providing subnanosecond pulses with invention may comprise a step recovery diode rise times of the order of 100 picoseconds at peak m fired by the discharge of three capacitors. The pulse voltages in the order of several hundred three capacitors are charged in parallel and then, volts. These switches, however, cannot be by means of fast switching avalanche transistors, operated at very high duty cycles because of are connected in series for discharge to obtain a mechanical limitations of a vibrating reed used voltage that is substantially equal to the sum of therein for the switching operation. Additionally, 15 the capacitor voltages when charged. The series' the mechanical contacts tend to deteriorate, coupled capacitors are then coupled via an output resulting in jittery and noisy pulses. Since the avalanche transistor to a differentiator, causing & deterioration of the mechanical contacts is pro- doublet pulse to be coupled to the step recovery portional to the number of times the contacts are diode. This doublet pulse triggers the step re- being opened and closed, the life of the switch is 20 covery diode stack to provide a fast rise time, high inversely proportional to the duty cycle. amplitude negative pulse of substantially nano- Another technique employed in the early prior second duration. art utilised Hertzian (spark gap) generators. These A pulse generator in accordance with the devices can supply pulses with amplitudes of the present invention will now be described in greater order of 1,000 volts and rise times of the order of 25 detail, by way of example, with reference to the 100 picoseconds at repetition frequencies above accompanying drawings, in which: — 200 Hertz. Hertzian generators, however, have a Figure 1 is a schematic diagram of a driver lifetime limited by the width of the spark gap circuit for the pulse generator according to the which determines the width of the generated present invention, pulse. 30 Figure 2 is a schematic diagram of the pulse One obvious solution to the mechanical and generator, responsive to the driver circuit of lifetime limitations of the mercury and Hertzian Figure 1, generators is to utilise solid state devices which Figure 3 is an equivalent circuit for the pulse are rapidly switchable and extremely reliable. It is generator of Figure 2 that is valid during the well known that tunnel diodes, avalanche 35 charging interval, and transistors (see Electronic Design, Volume 16, No. Figure 4 is an equivalent circuit for the pulse 6, 14th March 1968 at pages 202 to 209), and step generator of Figure 2 that is valid during the recovery diodes can be used to generate a series impulse interval. of impulse functions at a repetition rate sub- Referring to Figure 1, a driver 10, that may be stantially equal to the frequency of a driving 40 utilised for a short pulse generator in accordance function. Nanosecond pulses with rise times of with the present invention, comprises charging the order of 25 picoseconds are achievable with circuit 11, a switching circuit 12, a pulse shaping tunnel diodes. These generators, however, are circuit 13, and three capacitors C1f C2, and C3. The low amplitude devices achieving levels only of driver 10 further comprises transistors 11a, 11b, the order of 0.5 volts. Short pulses with ampli- 45 and 11c coupled in parallel to respective diodes tudes as high as 1,000 volts have been generated 11d, 11e,and 11f. Each transistor 11a, 11band 11c with a series stack of avalanche transistors. The may be of the type known in the art as MPS U10, rise and fall times of these generators is of the whilst each of the diodes 1 1 d, 1 1e and 1 1f may be order of 6 nanoseconds, which for many applica- of the type known in the art as 1N914. The tions is too slow. A significant improvement in the so junction of the cathode of the diode and the base pulse rise time has been achieved with the of the transistors for the parallel pairs 1 1 a — 1 1 d, combination of avalanche transistors and step 11b — 11e, and 11c — 1 1f are coupled via resistors recovery diodes. These devices exhibit rise times R-ia, Rib- and R1c, respectively, and a terminal 14 to of the order of 100 picoseconds, but provide peak a power supply (not shown), whilst the junction of amplitudes only of the order of 25 volts. A device, 55 the emitter of the transistor and the anode of the comprising a multiplicity of serially coupled step diode of these transistor-diode pairs are respec- recovery diodes, capable of providing pulse tively coupled to the capacitors C,, C2, and C3, and widths of 200 picoseconds and pulse amplitudes the collectors of the transistors 11a, 11b, and 11c in excess of 180 volts is disclosed in US — A — are respectively coupled to the terminal 14 via 3,832,568. The high pulse amplitudes of this 6o resistors R2a, R2b and R2o. Capacitors C1f C2, and C3 device, however, are achieved only when the are charged in parallel from the terminal 14 by pulse generator is operating into a high current flowing through the corresponding impedance resonant load. Additionally pulse transistors. The charging period is relatively rapid repetition rate of the device is limited to fre- since the current required for charging the quencies of the order of 40 kHz. 55 capacitors is effectively multiplied by the (3 of the EP 0 094 765 B1 transistors. Current continues to flow through the shorted end arriving at the input end after a time transistors 11a, 11b and 11c charging the capaci- lapse of 2 l2/v2, where v2 is the propagation tors Cu C2 and C3 until the leakage current velocity along the transmission line comprising through the diode, of each transistor-diode the pulse shaper 13. At the time the signal returns parallel combination, and the corresponding 5 to the input end of the pulse shaper 13, the avalanche transistor of the switch 12, as for transistor 1 2c is cut off causing the reflected pulse example transistor 12a for the transistor diode from the pulse shaper 13 to be coupled to the parallel combination 11a— 11 d, back biases the output terminal 23, thereby establishing a doublet base of the transistor. When this condition is pulse 24 thereat. The doublet pulse 24 will have a reached, the transistors 11a, 11b, and 11c are 10 positive peak amplitude h, substantially equal to turned off. This operation charges the capacitors 120V, a negative peak amplitude h2 substantially C1f C2, and C3 in parallel to the supply at terminal equal to 65V, and a total width t2 substantially 14, which may be 230 volts. equal to four nanoseconds, one cycle of a 250 During the charging period and the completion MHz wave, when, in addition to the parameters thereof, the avalanche transistors 12a, 12b and is previously stated, the circuit components have 12c are substantially at cut off, by virtue of a -6V the following values: supply coupled to the gate thereof from terminals 16a, 16b, and 16c, via resistors R3a, R3b, and R3c, Ria,b,c=150,000 ohms respectively, only leakage current flowing there- R2a^b,o=680 ohms through. A positive trigger pulse, from a series of 20 R3a,b!o=in'°no ohms positive trigger pulses 17 of width Tt and height A, R4a'b'=5,000 ohms coupled via a terminal 18 and diodes 21 and 22 to R5=2,000 ohms the base of the transistor 12a causes the latter to Cii2=150 picofarads avalanche, thereby placing the capacitor C, in A=4 volts series with the capacitor C2 and establishing a 25 t, = 15 microseconds voltage level at the anode of the diode 1 1 e that is I2=15.3 centimeters the sum of the voltages across the capacitors C, and C2. This sum voltage causes the diode 11e to A matching resistor R6 may be coupled to the conduct, placing the sum voltage on the collector output terminal 23 when an output pulse that is of the transistor 12b. The sum voltage over-volts 30 substantially ring free is desired. This resistor, the transistor 12b causing it to avalanche, thereby when of appropriate value (generally 50 ohms), placing the three capacitors C1f C2, and C3 in substantially eliminates multiple reflections series and establishes a voltage at the anode of between the transistor 12c and the output diode 1 If that causes it to conduct thereby terminal 23. Though this resistor significantly coupling the sum voltage of all three capacitors to 35 improves the pulse shape at the output terminal the base of the transistor 12c. The sum of the 23, it concomitantly decreases the peak pulse voltages across the three capacitors C1# C2 and C3 amplitude thereat and should be used only when causes the transistor 12c to avalanche, thus a substantially ring free output pulse is desired. completing the circuit to ground, via a pulse At the completion of the doublet pulse, which shaping network 13 which may be a length of 40 for the parameters given above may be con- coaxial cable, such as RG, 141/U, shorted at one sidered as one cycle of a 250 MHz wave, the end, wherethrough the capacitors C1r C2, and C3 transistors 12a, 12b and 12c are cut off; are discharged, thereby providing a pulse at an transistors 11a, 11b, and 11c are conducting; and output terminal 23. capacitors C1f C2, and C3 are being recharged to the The shape of the output pulse is determined by 45 repeat the above described process upon the smallest capacitor in a series chain which, for reception of a subsequent pulse in the pulse train example, may be the capacitor C3. This capacitor 17. short 30 of may be formed by a short length of semi-rigid RG Referring now to the pulse generator 141/U cable with an open circuit termination. The Figure 2, the doublet pulse 24 is coupled to a step discharge time for this capacitor determines the so recovery diode (SRD) 31 via a capacitor 32 and an pulse width and is given by 21-,/v-,, where I, is the inductance L A negative bias voltage, which may length of the cable and v-, is the velocity of be -6 volts, is coupled via a terminal 34, a resistor propagation therein. RG 141/U cable possesses a R7 and a choke inductance 35 to the SRD 31 to capacity of approximately one picofarad per establish an initial non; conducting state. A centimeter and will provide a pulse width of 55 capacitor 36 is coupled between ground and the approximately 2 nanoseconds when I, is substan- junction of the choke 35 with the inductance L. tially 5.3 centimeters. When the positive half cycle of the doublet pulse When the transistor 12c avalanches, one-half 24 is coupled to the SRD 31, it is rapidly switched the discharged energy from the capacitors C^ C2 into its conducting state, thereby providing a low and C3 is coupled to the output terminal 23 and 60 resistance path to ground. An equivalent circuit one-half is coupled to the pulse shaper 13, which for this condition is shown in Figure 3, wherein Vd comprises a shorted coaxial line of length l2. is the voltage drop across the SRD 31 and Rs is its Signals coupled to the pulse shaper 13 propagate series resistance in its conducting state. During its to the shorted end thereof, experience a phase forward conducting state, minority carriers are reversal thereat, and are reflected from the 65 stored in the SRD 31. These minority carriers are EP 0 094 765 B1 completely removed during the negative half by the switch means (12) during the conducting cycle of the doublet, abruptly driving the SRD 31 state of the switch means to provide said output to cut off. This abrupt cessation of the diode signal representative of the energy discharged current causes the energy stored in the magnetic from the energy storage devices (C1( C2, C3) the field of the inductance L to produce a half 5 output signal being one cycle duration having one sinusoid voltage impulse across the SRD 31 at the half cycle at a first polarity and one half cycle at a resonant frequency of the combination induc- second polarity opposite to the first polarity, the tance L and the reverse bias capacitance Cr of the apparatus still further comprising bistate means SRD 31. The equivalent circuit for this period of (31) coupled to the pulse shaper means (13) for operation is shown in Figure 4, wherein RL is the 10 switchably providing a conducting state when the load resistance. During this transition, the output signal is of the first polarity and to a capacitor 36 effectively provides a short to non-conducting state when the output signal is at ground, thus coupling the inductance L in parallel the second polarity. with the capacitor Cr and the load resistance RL. 2. Apparatus according to claim 1, charac- With this circuit, the impulse delivered across the 15 terised in that each energy storage device of the load resistance RL has a duration t0 given by: plurality of energy storage devices (C1f C2, C3) is a capacitor. nVlA 3. Apparatus according to claim 2, charac- to=- terised in that the charging means (11) comprises 20 terminal means (14) for coupling to a source of electrical energy, and a plurality of transistors V 1— (11a, 11b, 11c) each having an emitter coupled to 4R£-Cr one of the plurality of capacitors (G,, C2, C3) in that the switch means (12) comprises a plurality of The SRD 31 may be a MA 44483 manufactured 25 transistors (12a, 12b, 12c) each having a collector by Microwave Associates of Burlington, coupled to the base of a corresponding one of the Massachusetts. The reverse bias capacitance of transistors (11a, 11b, 11c) of the charging means this device is of the order of 1.4 picofarads. (11), for an initial transistor of the switch means Utilising this capacitance, an impulse width of the through to a penultimate transistor thereof an order of picoseconds may be realised with an 30 emitter coupled through one of the capacitors (C1f inductance L of 6 picohenries and a load C2, C3) to the emitter of a non-corresponding resistance RL of 50 ohms. In the actual circuit, transistor (11a, 11b, 11c) of the charging means parasitic capacitances cause the pulse width to be (11), the initial transistor (12a) of the switch of the order of 400 picoseconds. The peak ampli- means having a base coupled to receive trigger tude Ap of the pulse obtained with this circuit was 35 pulses (17) and an ultimate transistor (12c) of the of the order of 100 volts at a pulse repetition switch means having an emitter coupled to the frequency of 100 KHz, the repetition frequency of pulse shaper means (13), and a plurality of the trigger pulse sequence. unidirectional current conductive devices (11d, 11e, 1 If) being respectively coupled between the Claims 40 base and the emitter of a corresponding transistor (11a, 11b, 11c) of the charging means (11) and 1. Apparatus for generating signals of short poled so that, at a predetermined charge level of duration at an output terminal (23) in response to the capacitor coupled to the emitter, current flows a pulse coupled to input terminals thereof, the through the unidirectional current conductive apparatus comprising charging means (11) 45 device to set the transistor, corresponding to the having a conducting state and a non-conducting unidirectional current conductive device, in the state and coupled to receive energy from a supply non-conducting state. source (14) for supplying energy at an output 4. Apparatus according to claim 3 characterised means thereof whilst in the conducting state, in that the pulse shaper means comprises a switch means (12) having a conducting state and so coaxial cable (13) of predetermined length (l2) a non-conducting state, a plurality of chargeable having an inner conductor coupled to the emitter energy storage devices (C-,, C2, C3) coupled to the of the ultimate transistor (12c) of the switch charging means such that all are charged from means (12) at a first end, and an outer conductor the charging means substantially simultaneously, coupled to the inner conductor at a second end. and coupled to the switch means (12) so that the 55 5. Apparatus according to any of the preceding energy storage devices (C1f C2, C3) are coupled in claims, characterised in that one of the capacitors series when the switch means (12) is in the (C3) comprises a coaxial cable having an inner conducting state to provide an energy discharge conductor coupled to the charging means (11) path to the output terminal (23) for energy stored and an outer conductor coupled to the switch in the storage devices (C1r C2, C3) thereby provid- 60 means (12). ing an output signal representative of the energy 6. Apparatus according to any of the preceding discharged from the energy storage devices (C1f claims, characterised in that it further includes C2, C3), the apparatus further including pulse inductive means (L) having a first port coupled to shaper means (13) coupled to the output terminal the pulse shaper means (13) and a second port (23) and to the energy storage devices (G,, C2, C3) ss coupled to the bistate means (31) for storing EP 0 094 765 B1 8 energy when the bistate means is in the conduct- der Mehrzahl von Energiespeicherelementen (C1, ing state and for discharging stored energy when C2, C3) ein Kondensator ist. the bistate means is in the non-conducting state. 3. Vorrichtung nach Anspruch 2, dadurch 7. Apparatus according to claim 6, charac- gekennzeichnet, daft die Ladeeinrichtung (11) terised in that the inductor means has an induc- s AnschluBteile (14) zum AnschlulS an eine elek- tance value L and the bistate means is a step trische Energiequelle und eine Mehrzahl von recovery diode (31 ) having a reversed capacitance Transistoren (11a, 11b, 11c) umfalSt, die jeweils of value Cr, the reversed capacitance and the einen mit einem der Mehrzahl von Kondensa- inductor means being coupled in a parallel toren (C1, C2, C3) gekoppelten Emitter aufweisen, relationship during the non-conducting state, '0 dalS die Schalteinrichtung (12) eine Mehrzahl von thereby providing a voltage impulse that is half of Transistoren (12a, 12b, 12c) umfalSt, die jeweils a resonant frequency determined by a parallel einen mit der Basis eines entsprechenden der combination of a capacitor of value Cr and an Transistoren (11a, 11b, 11c) der Ladeeinrichtung inductance of value L. (11) gekoppelten Kollektor und einen Emitter 75 aufweisen, der fur einen ersten Transistor der Patentanspruche Schalteinrichtung bis zu einem vorletzten Transistor dieser Schalteinrichtung iiber einen 1. Vorrichtung zur Erzeugung von Signalen mit der Kondensatoren (C1, C2, C3) mit dem Emitter kurzer Dauer an einem AusgangsanschlufS (23) in eines nichtentsprechenden Transistors (11a, 11b, Abhangigkeit von einem Impuls, der Eingangs- 20 11c) der Ladeeinrichtung (11) gekoppelt ist, wobei anschliissen der Vorrichtung zugefiihrt wird, mit der erste Transistor (12a) der Schalteinrichtung einer Ladeeinrichtung (11), die einen leitenden eine zum Empfang von Triggerimpulsen (17) Zustand und einen nichtleitenden Zustand auf- angeschaltete Basiselektrode aufweist, wahrend weist und zum Empfang von Energie aus einer der letzte Transistor (12c) der Schalteinrichtung Speisequelle (14) angeschaltet ist, um Energie an 25 einen Emitter aufweist, der mit der Impulsformer- ihren Ausgangselementen zu liefern, wahrend sie einrichtung (13) gekoppelt ist, und dalS eine sich im leitenden Zustand befindet, mit einer Mehrzahl von in einer Richtung einen Strom Schalteinrichtung (12), die einen leitenden und leitenden Elementen (11d, 11e, 11f) jeweils einen nichtleitenden Zustand aufweist, mit einer zwischen der Basis und dem Emitter eines ent- Mehrzahl von ladbaren Energiespeicher- 30 sprechenden Transistors (11a, 11b, 11c) der Lade- elementen (C1, C2, C3), die mit der Ladeeinrich- einrichtung (11) angeschaltet und derail gepolt tung derart gekoppelt sind, daB sie alle von der ist, dalS bei einem vorgegebenen Ladungspegel Ladeeinrichtung im wesentlichen gleichzeitig ge- des mit dem Emitter gekoppelten Kondensators laden werden, und die mit der Schalteinrichtung ein Strom durch das in einer Richtung einen (12) derart gekoppelt sind, dalS die Energie- 35 Strom leitende Element flielSt, um den diesem speicherelemente (C1, C2, C3) in Serie geschaltet einen in einer Richtung einen Strom leitenden sind, wenn die Schalteinrichtung sich im leit- Element entsprechenden Transistor in den nicht- enden Zustand befindet, sodafS ein Energieent- leitenden Zustand zu bringen. ladungspfad zum Ausgangsanschlufc (23) fur die 4. Vorrichtung nach Anspruch 3, dadurch Energie geschaffen wird, die in den Speicher- 40 gekennzeichnet, dalS die Impulsformereinrich- elementen (C1, C2, C3) gespeichert ist, wodurch tung ein eine vorgegebene Lange (12) aufweis- ein Ausgangssignal gebildet wird, das die aus den endes Koaxialkabel (13) mit einem mit einem Energiespeicherelementen (C1, C2, C3) entladene ersten Ende mit dem Emitter des letzten Energie darstellt, wobei die Vorrichtung weiterhin Transistors (12c) der Schalteinrichtung (12) ge- eine Impulsformereinrichtung (13) einschlielSt, 45 koppelten Innenleiter und mit einem AulSenleiter die mit dem AusgangsanschlulS (23) und mit den umfassen, der mit dem Innenleiter an einem Energiespeicherelementen (C1, C2, C3) uber die zweiten Ende verbunden ist. Schalteinrichtung (12) wahrend des leitenden 5. Vorrichtung nach einem der vorhergehenden Zustandes der Schalteinrichtung gekoppelt ist, Anspruche, dadurch gekennzeichnet, date einer um das die aus den Energiespeicherelementen 50 der Kondensatoren (C3) durch ein Koaxialkabel (C1, C2, C3) entladene Energie darstellende Aus- gebildet ist, dessen Innenleiter mit der Ladeein- gangssignal zu liefern, das eine Dauer von einer richtung (11) gekoppelt ist und dessen AulSen- Periode aufweist, von der eine Halbperiode eine leiter mit der Schalteinrichtung (12) verbunden erste Polaritat und eine Halbperiode eine zweite, ist. zur ersten Polaritat entgegengesetzte Polaritat 55 6. Vorrichtung nach einem der vorhergehenden aufweist, une wobei die Vorrichtung weiterhin Anspruche, dadurch gekennzeichnet, dafS sie eine zwei Zustande aufweisende Einrichtung (31) weiterhin eine induktive Einrichtung (L) ein- umfalSt, die mit den Impulsformereinrichtungen schlielSt, die einen ersten mit der Impulsformer- (13) gekoppelt ist, um in schaltender Weise einen einrichtung (13) gekoppelten Anschluft und einen leitenden Zustand bei der ersten Polaritat des so zweiten mit der zwei Zustande aufweisenden Ausgangssignals und einen nichtleitenden Einrichtung (31) gekoppelten AnschlulS aufweist, Zustand bei der zweiten Polaritat des Ausgangs- um Energie zu speichem, wenn die zwei Zustande signals auszubilden. aufweisende Einrichtung sich im leitenden 2. Vorrichtung nach Anspruch 1, dadurch ge- Zustand befindet, und um gespeicherte Energie kennzeichnet, da(S jedes Energiespeicherelement 65 zu entladen, wenn die zwei Zustande aufweisende EP 0 094 765 B1 10

Einrichtung sich im nichtleitenden Zustand be- 3. Appareil selon la revendication 2, caracterise findet. en ce que le dispositif de charge (11) comporte 7. Vorrichtung nach Anspruch 6, dadurch ge- une borne (14) de couplage a une source kennzeichnet, daft die induktive Einrichtung einen d'energie electrique et plusieurs transistors (11a, Induktivitatswert (L) aufweist und dalS die zwei 5 11b, 11c) ayant chacun un emetteur couple a I'un Zustande aufweisende Einrichtung eine Speicher- des condensateurs (C,, C2, C3), en ce que le schaltdiode (31) mit einer Sperrkapazitat mit dispositif de commutation (12) comporte einem Wert (Cr) aufweist, und daft die Sperr- plusieurs transistors (12a, 12b, 12c) ayant chacun kapazitat und die induktive Einrichtung wahrend un collecteur couple a la base d'un transistor des nichtieitenden Zustandes parallel geschaltet 10 correspondant (11a, 11b, 11c) du dispositif de sind, sodalS ein Spannungsimpuls geliefert wird, charge (11), et, pour chaque transistor allant du der eine Haifte einer Resonanzfrequenz darstellt, transistor initial du dispositif de commutation a die durch eine Parallelkombination eines I'avant-dernier, un emetteur etant couple par I'un Kondensators mit dem Wert Cr und einer des condensateurs (C-,, C2, C3, a I'emetteur d'un Induktivitat mit dem Wert L bestimmt ist. 15 transistor non correspondant (11a, 11b, 11c) du dispositif de charge (11), le transistor initial (12a) Revendications du dispositif de commutation ayant une base couplee afin qu'elle regoive les impulsions de 1. Appareil generateur de signaux de courte declenchement (17) et un dernier transistor (12c) duree a une borne de sortie (23) en fonction d'une 20 du dispositif de commutation ayant un emetteur impulsion couplee a ses bornes d'entree, couple au dispositif conformateur d'impulsions I'appareil comprenant un dispositif de charge (11) (13), et plusieurs dispositifs (11d, 11e, 11f) de ayant un etat conducteur et un etat non conduc- conduction unidirectionnelle du courant couples teur et couple afin qu'il regoive de I'energie d'une respectivement entre la base et I'emetteur d'un alimentation (14) destinee a transmettre de 25 transistor correspondant (11a, 11b, 11c) du dis- I'energie a un dispositif de sortie, lorsqu'il est a positif de charge (11) et ayant une polarite telle I'etat conducteur, un dispositif de commutation que, a un niveau predetermine de charge du (12) ayant un etat conducteur et un etat non condensateur couple a I'emetteur, le courant conducteur, plusieurs dispositifs d'accumulation circule dans le dispositif de conduction unidirec- d'energie (Cn, C2, C3) qui peuvent etre recharges et 30 tionnelle de courant afin que le transistor, corres- qui sont couples au dispositif de charge de pondant au dispositif a conduction unidirec- maniere qu'ils se chargent tous a partir du tionnelle de courant, soit mis a I'etat non conduc- dispositif de charge de fagon pratiquement simul- teur. tanee et couples au dispositif de commutation 4. Appareil selon la revendication 3, caracterise (12) afin que les dispositifs d'accumulation 35 en ce que le dispositif conformateur d'impulsions d'energie (C-,, C2, C3) soient couples en serie avec comporte un cable coaxial (13) de longueur le dispositif de commutation (12) a I'etat conduc- predetermined (l2) ayant un conducteur interne teur et forment un trajet de decharge d'energie couple a I'emetteur du dernier transistor (12c) du vers la borne de sortie (23) pour I'energie dispositif de commutation (12) a une premiere accumulee dans les dispositifs d'accumulation 40 extremite, et un conducteur externe couple au (Cu C2, C3), avec formation d'un signal de sortie conducteur interne a une seconde extremite. representatif de I'energie dechargee les dis- par 5. positifs d'accumulation (C,, C2, C3), I'appareil Appareil selon I'une quelconque des revendications comprenant en outre un dispositif conformateur precedentes, caracterise en ce que I'un des condensateurs d'impulsions (13) couple a la borne de sortie (23) 45 (C3) est un cable coaxial et aux dispositifs d'accumulation d'energie (C1( ayant un conducteur interne couple au dispositif de charge (1 1 ) et conducteur C2, C3) par le dispositif de commutation (12) un externe couple au dispositif de commutation (12). lorsque celui-ci est a I'etat conducteur afin que le signal de sortie representatif de I'energie 6. Appareil selon I'une quelconque des dechargee par les dispositifs d'accumulation (C1f so revendications precedentes, caracterise en ce C2, C3) soit forme, le signal de sortie ayant une qu'il comporte en outre un dispositif inductif (L) duree d'un cycle dont un demi-cycle a une ayant une premiere voie couplee au dispositif premiere polarite et un demi-cycle a une seconde conformateur d'impulsions (13) et une seconde polarite opposee a la premiere, I'appareil voie couplee au dispositif (31) a deux etats afin ccfmprenant en outre un dispositif (31) a deux 55 qu'il accumule de I'energie lorsque le dispositif a etats, couple au dispositif conformateur d'impul- deux etats est a I'etat conducteur et qu'il decharge sions (13) et destine a donner, de maniere de I'energie accumulee lorsque le dispositif a commutable, un etat conducteur lorsque le signal deux etats est a un etat non conducteur. de sortie a la premiere polarite et un etat non 7. Appareil selon la revendication 6, caracterise conducteur lorsque le signal de sortie a la eo en ce que le dispositif inductif a une inductance L seconde polarite. et le dispositif a deux etats est une diode (31) a 2. Appareil selon la revendication 1, caracterise accumulation de charges ayant une capacite en en ce que chaque dispositif d'accumulation inverse de valeur Cr, la capacite en inverse et le d'energie parmi les dispositifs d'accumulation dispositif inductif etant couples en parallele a (C-,, C2, C3) est un condensateur. e5 I'etat non conducteur, si bien qu'une impulsion de 12 n EP 0 094 765 B1 tension qui est a la moitie de la frequence de parallele d'un condensateur de valeur Cr et d'une resonance determinee par la combinaison en inductance de valeur L est formee.

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