USRE24303E

USRE24303E - Semi-conductor trigger circuit

Info

Publication number: USRE24303E
Authority: US
Priority date: 1951-07-02
Publication date: 1957-04-16
Also published as: DE1036421B; US2651728A

Description

A ril 16, 1957. M, L wcpp Re. 24,303

' v saux-connuc'roa TRIGGER CIRCUIT Original Filed July 2, 1951 r 4 Sheets-Sheet l FIGJ. F|G.2.

CURRENT m MAI l23456789 l0'i|l2l3- \NVENTOR e m VOLTS MARION 1.. W000 'BY I ATTORNEY April 16, 1957 v W Re. 24,303

SEMI-CONDUCTOR TRIGGER CIRCUIT .Original Filed July 2. 1951 4 Sheets-Sheet 3 g IN VOLTS FlG.2d.

0 IO p o 'vw mmauuna mvzmoh MARION L. wooo ATTORNEY United States Patent:

1. 24,3113 SEMLCONDUCTOR TRIGGER, CIRCUIT MiirlonLoren Wood; Ulster County, N. Y., assignor to International Business Machines Corporation, New York, N. Y., a corporation of New York o i' a 1v..2, 6s1 ,72s, dated September s, 1953, set-n1 0. "234,837; any 2, 1951'; Application for reissue Alignstlp,"1955,.SerialNo. 529,502. reclaims. c1.- save-88.5.

Matterjenclosed'in heavy. brackets appears in the orlglnialpatentbutf fbrm's nop'art of this reissue specificafionr'matter printed in italics indicates the" additions mi'cle by reissue;

This inventionrelates inigenerat to a trigger circuit and in particularto a bi-stable trigger circuit arrangement employing 'a' pair ofsemi-eonduetive elements.

The principal obj-ectof the invent-ion is. to provide a trigger circuit including a pair: of semi-conducting elements and having twoz-stable st'atesof. equilibrium.

Another object ofth'e invention is' to provide a bistableqxtrigger circuit including. a pair of variable impedancezelements each of which. is. characterized by a regiomofi positivevariational resistanceaand a region of negative variational resistance.

A further object of the'invention is to provide a bistable trigger circuit includinga: pair of semi-conducting elementscinwhichthe triggeringaction does not depend upon.- aregenerative or positive feedback circuit connection:

A still further object of the invention is to provide a bi-stable trig'ger circuit includingi a pair of semi-conductorseach of which is characteri'zed -by the current flowing therethl'oughbeing-- a 'bi-valued function of the voltage.

ether objects ofthe: invention will be pointed out in the: following description andclaims and illustrated in "rig drawings, which disclose, by way of examples, th principle of the invention and the best mode, whichhas'been contemplated, of applying that principle.

In the drawings:

Fig. 1 is a's'eries circuit including a crystal diode, a resi-storEand-a source of potential;

Fig-. Z is a circuit diagram representative of the main embodimentof the invention;

' Figs: 2a, 2b, 2c and Zd'are a-series of characteristic curves' rep'resenting' the operatingconditions of the circuit ar angement orFigi 2-;

Big". 3 i's'a'modific'ation of-Fig. 2in which a three elect'rode semhconductorelement is used inplace of a crystal diodeg i Fig; his a series'of characteristic curve-s representing the operating conditions ofFig. 3;

Fi'gs'z' 4 and 5' are modificationso'f the circuit arrangement ofFig 3;'and

Fig. isa binary counter arrangement incorporating the present invention.

crystn diode includes a minute block of doped semiconductor which is characterized by a region of positive variational resistanceand a region of negative variational resistance such as, for example, germanium or silicon; The semi-conductor block is plated with rnetal on one surface and connected with an extremely fine metallic whisker on the parallel surface. The positive resistance characteristic of the diode may be defined as one; in" Which there i s'a change in current in the same sense to; each change of potential, while in the case of the negative resistance characteristic the current varies inversely withthewoltagcr Now; referring in-detail to Fig. 1-, there. is shown. therein a source of operating potential 12 of the'magnitude of approximately 315 volts, a 0.92 megohrn resistorv 11 and a crystal diode 10, all connected in series. The crystal diode 10 includes a-bloclt of semi-conductor material 17 which isplated with a metallic base 13 on one surface and connected with an extremely fine metallic whisker 14 on a parallel surface. The intersection of the-load line 13 and the crystal diode characteristic'curve 9 at point 20-, as'shown in the diagram ofFig; 2a, determine the operating point for this series circuit arrangementwhere the values of the source of potential 12 and the resistor 1 are so selected such that theload line 18 willintersect curve 9 in its region of negative variational resistance;

it the input characteristic of this series'circuit arrange: ment is determined across the terminals 15 and 16 (Fig. 1) it will be found to be thatas shown 'by the curve 21 (Fig. 2b). It now becomes apparent that this input characteristic curve 21 serves in reality as a. load line for'any device that may be connected in parallelwith the diode 10. With regard to the input characteristic curve 21, it has been determined experimentally that the diode'lt) is in a region ofpositive variational resistance for the portion 21b to 210 of the curve 21 andiin a region of negative variational resistance for the portion 21b to 21a of the curve 21. Now if a second crystal diode 22 is connected in parallel with the diode 19, such as shown in Pig. 2, it will be seen that the input characteristic curve 21 intersects the curve 55 representative of the characteristic of the crystal diode 22 at the stable points of operation 23 and 24 (Fig. 2c). The input characteristic curve 56 (Fig. 2b) represents the characteristic obtained when one looks into a series circuit similar to that of Fig. 1' in which the crystal diode 22 is used in place of the diode it). it is to be noted that if diode 22' were identical to diode 19, curve 56 would be identical to curve 21; however, for the sake of generality, it is assumed that the diodes are not identical.

The circuit diagram of Fig. 2 represents the main embodiment of the invention and functions as a trigger circuit in a manner to be presently described. When the trigger circuit is on or in one of the two stable operating positions, the'crystal diode 10 operates at point 57 (Fig, 2d) in its region of negative resistance while the crystal diode 22 operates at point 23 in its region of positive variational resistance. In this operating position it is to be noted from Fig. 2d that the diode 10 is at the higher while the diode 22 is at the lesser of two current conditions with the voltage'drop across the two diodes being necessarily the same, because they are connected in parallel. In the other stable state of equilibrium, arbitrarily called the off state, crystal diode 22 will operate at point 24 in its region of negative variational resistance, while the diode 10 operates at point 58 in its region of positive variational resistance. In this operating position, the current flow through the diode 22 will be at the higher of two values While the current flow through the diode 10 will be at the lower of two values. Also when either of the crystal diodes is operating in its region of negative variational resistance, the current therethrough exceeds that through the other crystal diode which is operating in its region of positive variational resistance.

Assuming that in one state of equilibrium one of the diodes will be in a positive resistance region While the other diode will be in a negative resistance region, the triggering of the circuit arrangement of Fig. 2 may be brought about through the manipulation of the

switches

25 and 26. When the switches are operated in a manner to be presently described, the diodes will assume the operating positions of the other state of equilibrium such that the diode. in the positive resistance region will shift to the negative resistance region while the diode in the negative resistance region will shift to the positive resistance region. This may be shown by referring to Fig. 2 and assuming that the switch 25 is closed while the switch 26 is open causing diode to operate at point (Figs. 2a and 2d) in its negative resistance region. Now with the switch in a closed position, the closing of switch 26 will connect the diodes 10 and 22 in parallel but since the voltage available to the diode 22 is less than the peak inverse voltage, as represented by point 27, the diode 22 will operate in a positive resistance region at position 23, and diode 10 will shift in its operating point to 57 due to the presence of diode 22 in the circuit. Now if we open the switch 25 and leave the switch 26 closed, the diode 22 will switch from the operating point 23 located in its positive resistance region to the operating point 59 in the negative resistance region inasmuch as the magnitudes of the battery 12 and the resistor [17] 11 have been so selected as to cause the single diode to assume this negative position. Next, if We close the switch 26 with the switch 25 also in a closed position, the diode 10 will assume operating point 58 in the positive resistance region inasmuch as the voltage available to the diode 10 at this time is less than the peak inverse voltage while the diode 22 will remain in the negative resistance region but will shift to position 24.

A modification of Fig. 2 which offers a more practical arrangement for producing a change in the statusof the trigger circuit is shown in Fig. 3. In this modification each of the crystal diodes is replaced by a crystal triode or transistor, as it is more commonly known.

The crystal triode or transistor 28 (Fig. 3) includes a block of semi-conductive material which is plated with a metallic base 29 on one surface and connected with a pair of extremely fine

metallic electrodes

30 and 31, commonly referred to as the collector and the emitter, respectively. The collector 30 is coupled to the negative side of a 67.5 volt supply source 32 While the emitter is coupled to the positive side of said source through a 13,000 ohm resistor 33. The base electrode 29 is coupled through a 430 ohm resistor 34 to the junction of the emitter electrode 31 and the resistor 33. These various connections of the three electrodes cause the collector 30 to be biased negatively with respect to the remaining two

electrodes

29 and 31 while the emitter 31 is biased positively with respect to the base electrode 29. A second transistor or variable impedance element 35 is connected in parallel with the triode 28. The triode 35 has a base electrode 36, a collector electrode 37, and an emitter electrode 38 which are connected in the manner as previously described for the identical electrodes of the triode 28. The

pulse generators

39 and 40 representative of a source of out-of-phase negative pulses are connected through the corresponding

capacitors

41 and 42 to the

respective base electrodes

29 and 36 of the

transistors

28 and 35.

As is well known, and as pointed out in the copending application of A. H. Dickinson, Serial No. 208,966, filed February 1, 1951, a variation in the emitter potential produces a change in the collector characteristic curve 43 (Fig. 3a) which curve is similar in nature to the characteristic curve 9 (Fig. 2a) of the crystal diode. The collector characteristic curve 43 is representative of the characteristic curve obtained for the triode 35 while the curve 66 is the characteristic curve for the triode 28. The input

characteristic curves

62 and 61 were obtained in a manner similar to that described with reference to Fig. i where curve 61 is the input characteristic with triode 28 in series with source of potential 32 and resister 33, and curve 62 is the input characteristic when triode 35 is similarly employed.

The method of causing a shift in the status of the trigger circuit of Fig. 3 will now be described with an 4 initial assumption being made that the transistor 35 is operating at point 45 in the positive variational resistance region of the curve 43 and the transistor 28 is operating at point 46 in the negative variational resistance region of, the curve 60 (Fig. 3a). It is to be observed from Fig. 3a that at this position of stability the current through the transistor 35 is at the lower of two values while the current through the transistor 28 is at the higher of two values.

Upon applying a negative pulse from the source 40 through the capacitor 42 to the base electrode 36 of the transistor 35, the emitter to base potential thereof will be increased thereby causing a shift in the characteristic curve 43 to the dash line curve 47 as explained in the A. H. Dickinson application Serial No. 208,966. The change in the collector characteristic curve reduces the voltage at which the transistor 35 goes into its region of negative variational resistance and as a result the transistor 35 shifts to the operating point 48. The operating point 43 of the triode 35 will shift to operating point 63 upon the cessation of the negative pulse applied to the base electrode. With the transistor 35 operating in its region of negative resistance, the transistor 28 shifts from point 46 to operating point 64 in the positive resistance region as demanded by the stability criteria of the circuit. Thus a change in status of the trigger circuit of Fig. 3 has occurred in which the transistor 28 is operating at position 64 while the transistor 35 is operating at position 63. In this new stable point of equilibrium the current flow through the transistor 35 is now at the higher of two values 'while the current flow through the transistor 28 is now at the lower of two values.

In a similar manner, the application of a negative pulse from the source 39 through the capacitor 41 to the triode 28 will switch the trigger back to the status originally assumed.

A modification of Fig. 3 is shown in Fig. 4 wherein the functions of the emitter and base, as shown in Fig. 3, are interchanged, and a pair of resistors, 50 and 53, for purposes of deriving an output, are added. In this arrangement of Fig. 4, the collector electrode 30 of the transistor 28 is connected to the negative side of the battery through the resistor 50 while the emitter 31 is coupled to the positive side of the battery 32 through a pair of

resistors

34 and 33. The source of positive pulses 39 is coupled through the capacitor 41 to the emitter electrode 28. The transistor 35 which is connected in parallel with the transistor 28 is similarly coupled. In this modification the emitter electrode is made positive with respect to the base electrode thereby enabling the circuit to be made responsive to positive pulses instead of negative pulses.

A further modification of Fig. 3 is that shown in Fig; 5. In this modification the collector electrode 30 is coupled to the negative terminal of the battery 32 through a parallel impedance network consisting of the 570 ohm resistor 50 and the .0056 microfarad capacitor 51. In like manner the collector electrode 37 is coupled through the parallel network consisting of the 570 ohm resistor 53 and the .0056 microfarad capacitor 52 to the negative side of the battery 32. A source of negative pulses 54 is jointly coupled through the

capacitors

41 and 42 to the

respective base electrodes

29 and 36. The insertion of the impedance network in each of the collector circuits in addition to the joint coupling of the pulse source with the base electrodes of each transistor enables the circuit arrangement of Fig. 5 to function as a well known flipfiop circuit in which successive negative pulses applied simultaneously to each of the base electrodes causes the trigger to reverse back and forth in status.

For example, let it be assumed that the transistor 35 is operating at point 63 (Fig. 3a) in the region of negative resistance while the transistor 28 is operating at point 64 in the region of positive resistance when a negative pulse is simultaneously applied to the baseelectrodes of the

triodes

28 and 35. The negative pulse applied to causingthe transistor-28 to shift to thenegative resistance region which, in turn, will cause the transistor 35 to; shift to the positive resistanceregion-thereby resulting in the trigger circuit assuming/the other state of equilibrium.

The next-following. negative pulse will cause the trigger circuit to-shift; back to its original state of equilibrium.

In Fig.6, a two stage pulse counter is formed by capacitively' coupling the trigger circuit of Fig. 5 with a similar trigger circuit. While only two stagesare shown it is pointed out-,that it iswithin the scope ofthe invention to connect two or more trigger circuits as a decade counter in amanner which is well known in the art. The output taken across-the resistors 53 of the first stage is applied jointly through the 0.05 microfarad capacitor 54 to each of.the base electrodes of the second stage such that exchange instatus of the second stageoccurs for only every. second, negative pulseapplied to'th'e input side of the. first. stage.

While there have been shown and" described and pointed'out the-fundamental novel features of the invention as applied' to a preferred embodiment, it will be understood th'at various omissions and substitutions and changesin the form anddetails of the device illustrated and in" its operation may be made by those skilled in the art,, without departingtrom the spirit of the invention. It-is the intentionj. herefore, tobe limited only as. indicat'ed'by' the scope ofthe following. claims.

What is. claimed is:

1'. A bi-stable trigger circuit comprising a plurality of variable impedance elements, each having a current/voltage relationshipsucli that the current is a multi-value functionof the voltage, a source of current and'means for initiating a change in the distribution, of the current flow fromsaid source [of current] between said'elements, the current through one ofsaid'elements in one stateof equilibrium exceeding the current through the other of said elements, while the current through said other of said elements in the other state of equilibrium exceeds the current through said'one. of said elements;

2. A'trigger circuit 'having two stable operating conditions comprising apa'ir of parallel connected variable 'impedanc'e'elements, each including a semi-conductor element having different [resistance] impedance characteristics in each-of saidconditions, a: source of current, the current flow through one of said'elements being greater than that" through the other ofsaid elements in-one of sai'd'conditions, and viceversa,.in the. otherof said conditions, and means for initiating a change in the distribution of the current flow from saidsource [of current] between said elements.

3. In a trigger circuit having two, stable states of equilibrium, a pair of [crystal] semi-conductor diodes, a source of potential,- impedance means, means-- for" sequentially'coupling firstone-of said'diodcs in series with said source and-impedance means, then saiddiodes in parallelwitlr said source and-impedancemeans', and then the otherof saiddiodesin'serieswith said source and said impedancesuchthat-'the-status of said trigger shifts from =one stiate-of equilibrium to another.

4. A bi-stabletriggercircuit comprising a pairof variableimpedanceelements each having a characteristic including a region of positive and negative variational resistance, a source of potential and a resistor serially arranged, and means for sequentially coupling first one of said elements and then the other of said elements in series with said resistor, said circuit shifting from one status to the other as said elements are serially coupled by said sequential means.

5. A trigger circuit having two stable points of equilibrium comprising [a] first and second semi-conductor devices, each having a plurality of electrodes, means for applying operating potentials to said elcctrodes[,] including means for coupling said first and second semiconductor devices. in paraliei, a nd, rneans foralternately applying [ncgativelinpnt pulses iQ i'QIXG Ofsaid-electrodes of-said first and second sem conductor dev-icesforcausing a shift; in status of said trigger circuit.

6.- A bi-stable triggercircuit comprising [al.first and second-[crystal triode]. transistors; each having a collector, an. emitter. and; a base electrode-- coupled to a semi conductive elemcnt,,- means for coupling [said first and-second triode inparallel] atleast two- 0f the electrodes of one transistor to corresponding electrodes 0f the other transistor by respective direct' connections, means including; a common impedance elementf.fotapplying operating potentials; to" said first and second [triode] transistors, there being no cross-connection be tween-the electrodesofi sa-idtransistors,;.- and-pulse means coupledttoeachsaidbase electrode for sequentially causing a shift in statusof saidcircuit.

7-.v A trigger circuit'having, two stable-states of equilibriurncomprising; a-pair; of semi-conducting. elements, each'having, a characteristicincluding a region of positive and-negative variational re'sistancqeachof said elementshavingiabase electrode-an emitter electrode, and a'collector electrode,- means for-connecting said elements in parallellj, meansla'nd. forapplyingoperating potentials thereto including a common impedance element [for applying operating potentials tosaid" elements]; one of said elements being in'the region-of negative resistance while'the otherofsaidvelernents is-insthe region'- of positive resistance when said circuit'isin-one of said states of equilibrium, and means for applying a negative pulse to'the base electrode of; saidother of said'elements to cause said circuit to shift tothe other of said states of equilibrium;

8. A trigger circuithavi-ng two stablestates of equilibrium comprising. a first [crystaltriode]-.transistor including a first collectorelectrode,.-a first emitter electrode, a first base. electrode and a. first semi-conducting element, [means for; disposinglsaid electrodes [in operating relationship, with] operatively. contacting said element; asource, of operating'zpotntial having positive and negative terminals, a' first impedance network including a resistor and capacitor in-parallehmeans for coupling said collector, electrode to said; negative terminal through said network, a-first resistor means for coupling a said base electrode to said emitter electrode, asecond [crystal triode]: transistor having;- a second collector electrode, a second emitter electrode,:a secondbase .electrod'e, and a second semi-conducting clement,-said second electrodes operatively contacting-said second'element, a second impedance network including a resistor and capacitor in parallel, means: for couplingasaid second collector electrode; to said negative" terminab through said: second network, a secondresistorme'ans' for coupling said second base electrodeto saidj second emitter electrode, impedance means commonly. coupling said first and second emitter electrodes tosaid positive terminal, and a source of negative pulses: commonly coupled to said first and second base. electrodes.

9. An impulse counter-circuit arrangementcomprising a first stage includinga first triggercircuit and a second stage includingasecon'd trigger" circuit, said first'and second circuits each comprising a pair of scmi-conducting elements, each includingabaseelectrodeg-anemitter electrode, a collcctor electrode, and a semi-conductor'body, said electrodes operatively contacting the corresponding semi-conductor body, a source of potential, means for positively biasing each said emitter electrode with respect to the corresponding base electrode, means for negatively biasing each said collector electrode with respect to the corresponding base electrode, resistor means for commonly coupling each said emitter electrode of said first and second circuits to the positive terminal of said source of potential, means for applying the output signal of said first stage to said second stage, and means for applying negative pulses to said first stage.

said electrode being operably coupled said semi-conductor bodies, means transistors, each including [a] collector, emitter,- and base electrodes, and a semi-conducting element, each to the associated one of said elements, a source of operating potential having positive and negative terminals, means for coupling each said collector electrode to one of said [negative] terminals, means including a resistive element for coupling each said emitter electrode to the corresponding base electrode, means commonly coupling each said base electrode to the other of said [positive] terminals, and means including a source of pulses of predetermined polarity commonly coupled to said base electrodes.

11. A pulse counter circuit arrangement comprising [a] first and second trigger circuits, each said circuit comprising a pair of semi-conducting devices, each including a base electrode, an emitter electrode, a collector electrode, and a semi-conductor body, each said electrode operatively contacting the corresponding one of for [positively] biasing each said emitter electrode in ne polarity with respect to the corresponding base electrode, means for [negatively] biasing each said collector electrode in the opposite polarity with respect to the corresponding base electrode, means for applying the output signal of said first trigger circuit to said second trigger circuit, and means for applying pulses of a predetermined polarity to said first trigger circuit.

12. A bi-stable trigger circuit comprising first and second transistors, each having a collector, an emitter,

and a base electrode coupled to a semi-conductive element, means for coupling at least two of the electrodes of one transistor to corresponding electrodes of the other transistor by respective direct connections, means including a common impedance element for applying operating potential to the transistors, there being no crossconnection between the electrodes of said transistors, and pulse means coupled to each said emitter electrode for sequentially causing a shift in status of said circuit.

13. A circuit comprising first and second transistors, each having a control electrode and an output electrode, means for coupling at l ast two of the electrodes of one transistor to corresponding'electrodes of the other transistor by respective direct connections, means including a common impedance clement connected to said output electrodes for applying operating potentials to the transistors, there being no cross-connection between the electrodes of said transistors, and pulse means coupled to each said control electrode for controlling the current flow through said common impedance element.

14. In combination, a plurality of transistors having a like electrode of each tied together and to a common load impedance, means for operatively biasing said transistors through said common load impedance, and pulse means coupled to each transistor to control the current flow through said common impedance.

15. In combination, a plurality of transistors having a like electrode of each tied together and to a common load impedance, means for operatively biasing said transistors through said common load impedance, and a plurality of independent signal means, each individually coupled to a respective transistor to control the current flow through said common impedance.

.a respective electrode 16. A bi-stable circuit comprising a pair of transistors, each having an emitter electrode, a base electrode, and a collector electrode, means for operatively biasing said electrodes including a source of potential and a resistor serially arranged and means connecting both said emitter electrodes together and through said resistor to said source, said resistor being effective to limit the total current from said source to a value suflicient to maintain one only of said transistors substantially conductive, and means operable when either transistor is substantially conductive to reduce the impedance of the other transistor, thereby reversing the conducting states of said transistors.

17. A bi-stable circuit comprising a pair of transistors, each having an emitter electrode, a base electrode, and a collector electrode, means for operatively biasing said electrodes including a source of potential and a resistor serially arranged and means connecting both said base electrodes together and through said resistor to said source, said resistor being efiective to limit the total current from said source to a value suflicient to maintain one only of said transistors substantially conductive, and means Operable when either transistor is substantially conductive to reduce the impedance of the other transistor, ther by r versing the conducting states of said transistors.

18. A bi-stable circuit comprising two semi-conductor diodes, each having two electrodes, a source of p0tential and a resistor serially arranged, means connecting of each of said diod s through said resistor to said source, said resistor being effective to limit the total current from said source to a value sufficient to maintain only one of said diodes substantially conductive, and means operable when either diode is substantially conductive to reduce the impedance of the other diode, thereby reversing the conducting states of said diodes.

19. A bi-stable circuit comprising two semi-conductive devices, each having at least two electrodes, means for operatively biasing said electrodes including a source of potential and a resistor serially arranged, and means connecting a respective electrode of each of said devices together and through said resistor to said source, said resistor being eflective to limit the total current from said source to a value suflicient to maintain only one of said devices substantially conductive, and means operable when either device is substantially conductive to reduce the impedance of the other device, thereby reversing the conducting states of said devices.

References Cited in the file of or the original paten UNITED STATES PATENTS this patent t