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Feb. 25, 1958 HUO-BING YIN 2,824,964 SEMI-CONDUCTOR OSCILLATOR CIRCUITS‘ Filed June 28, 1955

OUTPUT

INVENTOR. HUD-BIND YIN ‘BY

A 7703 Ni V 2,824,964 United States atent O ” ice Patented Feb. 25, 1958 I 2 its organization and method of operation, as well as addi tional objects and advantages thereof, will best be under stood from the following description when read in con 2,824,964 nection with the accompanying drawing, in which: SEMI-CONDUCTOR OSCILLATOR CIRCUITS Figures 1 and 2 are schematic circuit diagrams of oscil lator circuits utilizing and embodying Hue-Bing Yin, Collingswood, N. J., assignor to Radio two possible forms of the present invention. Corporation of America, a corporation of Delaware Referring now to the drawing, wherein like parts are Application June 28, 1955, Serial No. 513,469 indicated by like reference numerals in both ?gures, and 10 referring particularly to Figure 1, an oscillator circuit 6 Claims. (Cl. 250-36) embodying the invention includes a 8, which may be considered to be an N-P-N junction transistor of the tetrode type. The tetrode transistor includes a semi conductive body 10, with which four electrodes are co~ This invention relates to electrical signal generator or 15 operatively associated in a well known manner. These oscillator circuits, and in particular to circuits of that type electrodes are designated, as is conventional, as an emitter utilizing semi-conductor devices, such as transistors as 12, a collector 14 and a ?rst and second base electrode 16 operative elements therein. More particularly, the pres and 18 which may be referred to as a normal base elec ent invention relates to oscillator circuits utilizing tetrode trode 16 and an auxiliary base electrode 18. The con transistors, that is, transistors having four electrodes. 20 struction and characteristics of transistors of this type in order to produce sustained by electrical have been described in an article by Wallace et al. in the means, it is necessary to feed back a portion of the out November 1952 issue of the Proceedings of the I. R. E., put signal from a signal amplifying device, whether it be starting on page 1395. While the tetrode transistor 8 an electron tube or a transistor, to the input circuit of the has been illustrated as being P type conductivity, it could device. To this end, many of the known oscillator circuits 25 also be of N type conductivity, that is, a P—N—P junction contain an external path which couples signal transistor, so long as the polarity of the various required energy from the output circuit to the input circuit of the were reversed. amplifying device of proper phase and amplitude to sus The ?rst or normal base 16 of the transistor 8 is con tain continuous . nected directly to a point of reference potential or ground. In other oscillator circuits, a reduction in the number Alternatively, it could be connected through a suitable by of required circuit components and hence circuit simplicity passed to ground. The auxiliary base 18 is con is achieved by utilizing the interelectrode capacitances of nected through .a suitable resistor 29 to the negative ter the signal amplifying device to provide the feedback neces minal of a source of direct-current biasing , such sary for oscillation. In still other oscillator circuits, a de as illustrated by a battery 22, the positive terminal of vice having a negative resistance characteristic is utilized, 35 which is grounded. The resistor 2% and the battery 22 and by properly connecting a tuned circuit across the nega are bypassed by a capacitor 24 which is connected from tive resistance, sustained oscillation is achieved. This the junction of the auxiliary base 18 and the resistor 20 latter method has been utilized with success in oscillator to ground. circuits using point-contact transistors and also results Suitable ‘determining means for the oscilla in circuit simplicity. For high frequency applications, tor circuit are provided by provision of a parallel resonant 40 however, such as those required for television receiving tank circuit 26 comprising an inductor 28 and a capacitor systems, for example, it is often di?icult to obtain high fre 30, which may be variable as shown for tuning the oscil quency oscillations with circuits which require but a mini lator circuit to the desired fundamental frequency of mum number of circuit components. operation. The upper or high ‘frequency end of the tank It is, accordingly, an object of the present invention 45 circuit 26 is connected as shown to the collector 14 of to provide an improved oscillator circuit utilizing a four the transistor. The lower end of the tank circuit 26 is electrode junction transistor. connected through a suitable radio frequency 32 It is another object of this invention to provide an im to the positive terminal of a source of bias proved semi-conductor circuit for generating sustained ing voltage, such as illustrated by a battery 34, the nega relatively high frequency sine-wave oscillations and which 50 tive terminal of which is grounded. The choke 32 and the includes relatively few circuit components. battery 34 are by-passed by a capacitor 36 which is con It is yet another object of the present invention to pro nected from the junction of the tank circuit 26 and the vide an improved very high frequency oscillation genera choke 32 to ground. The generated oscillations may be tor utilizing a tetrode transistor, which may provide derived from any suitable point in the oscillator circuit. reliable operation with relatively simple circuit con 55 Preferably, they are inductively coupled from the induc-v struction. tor 28 of the tank circuit. To this end, an output wind These and further objects and advantages of the present ing 38 is provided which is inductively coupled to the in; invention are achieved by utilizing the negative resistance ductor 28 of the tank circuit 26. characteristic of the collector circuit of a tetrode transis As was mentioned hereinbefore, it has been discovered, tor. It has been found, in accordance with the invention, in accordance with the invention, that the collector cir that a suitable negative resistance characteristic can be ob 60 cuit of a tetrode transistor will exhibit a negative resist tained in a tetrode transistor by suitably biasing the nor ance characteristic over a portion of its operating range mal and auxiliary base electrodes of the device and open if suitable biasing voltages are applied to its normal circuiting the emitter electrode. This negative resistance and auxiliary base electrodes and its emitter electrode characteristic'may be effectively utilized to generate sus is open circuited. To most effectively utilize this nega tained oscillation. By capacitively coupling the emitter 65 tive resistance characteristic and to provide optimum cir directly with the collector, however, in accordance with cuit operation for the oscillator circuit, in accordance the invention, circuit'operation may be improved and with this invention, a capacitor having a small capaci very high frequency oscillations obtained. tance is used to couple the emitter of the tetrode tran ‘ The novel features that are considered characteristic of sistor with its collector. 70 Accordingly, in Figure l, a. this invention are set forth with particularity in the ap capacitor 40 is coupled directly between the emitter 12 pended claims. The invention itself, however, both as to and the collector 14 of the transistor 8. ’ 2,824,964

The capacitor 40, in a typical example, may have a ' trode, the combination comprising, means providing :a capacitance 'of from 2 to 4 micromicrofarads. By con ?rst sourceof energizing potential connected between necting the capacitor 4ti'as shown, that is, between the ‘ said auxiliary base electrode and said point-of reference ‘ emitter: and the collector; of the‘ transistor,: andibyu'sing potential, means connecting said norinalbase electrode to advantage ? the collector circuit"negativefresistance { of 5 with said point of reference potential, a frequency deterf ~ the transistor, 'it 'has been: found'ithat‘ high? frequency,‘ mining circuitconnected with said collector electrode, stable and sustained jsine-wav'ef ‘oscillations; of relatively» means providing, a secondsource of energizing poten- ' ' high amplitude may be generated. This is accomplished,’ tial connected between said frequency determining'cir moreover, by. a circuitiin which’ a minimum ‘number of» cuit and said ‘point of‘refere'nce potential, said inseam 71 circuit components are utilized and the. circuit' connec second sources of: energizing potential beingf'e?ective'toi Vtions therefor‘are relatively simple. A circuit inv accord-I 7. 7 applyrbiasing voltages solely to said collector, normal " ance with‘ithe' invention hasibee'ni'found moreover; to' base, and auxiliary base electrodes to providedawnega operate over a 'relatively' Wide range‘ of , tive resistance characteristic, in the collector circuit of’ _, 'i which'may be tuned by varying the capacity of the capac said tetrode transistonandv a 'coupling' capacitor’ con ' it'or?t). , In- addition, emitter biasing-is-"not required." nected between said emitter electrode and the junction]; ~ and it, has‘been‘ found that the required biasing voltages of said collector electrode and said frequency'determiné between‘ ‘the‘b‘ase electrodes of theftransis'tor'is less criti- " ing ‘circuit to ,enhanceljsaidlene'gative, resistance charac- V cal‘ than that-required'in conventional tetrode transistor ter-istic and provide optimum: operationofsaid ‘oscillator t oscillator circuits. The oscillator signals sor'generated circuit. - , 7 may be derived from across the coupling winding 38 and ' 3. {a ‘sine _wave-1oscillator, the‘ combination with 'a' ’ , ' . used; for example, to supply the- signals tetrode‘ transistor having" an emitter; a collector; ainor-i in a television receiver.’ ' ' mal' base-i electrodeiand; an“auxiliaryjbase electrode; of An oscillator circuit constructed in'accordance with 7 means forapplying:energizingfpotentials','solely'to said the teachings of the present invention‘ has been found’ auxiliary *base; . normal base'gand collector electrodes; 'a ' to contain a considerable number, of harmonic frequency frequency determining circuit for" the *oscilla'tori'connebtéd. signals in' its collector circuit. In Figure, 2, this char witht'tsaid' collector‘elect‘ro‘de‘» and ‘tunablelitolapréderf ' 7 'acteristic, has been utilized to advantage to obtain even termined‘ operating‘ frequency‘:andimeansi' providing a' higher frequency ‘operation by coupling a second fre» negative resistance characteristic for said‘ irans'is‘tol‘floverr quency determining tank circuit with ‘the collector 14. of 1 a portion Gifits' operating'ran'ge including‘ said‘?fstname'd' the transistorJj This tank circuit'will‘ normally be tuned means and‘ a capacitorconne'ct‘ed from‘ said’ ‘emitter? ele'c-f to the frequency of the harmonic signal which it is de V trade to the ‘junction of"saidcollector' electrode"and saidL sired’ to derive .from the' circuit.v 1To accomplish this, frequency determiningcircuit. ' ' ' a second parallel resonanttank circuit 42 is provided ' 4; infa sine-wave oscillatorftheV combination Ea , which includesain inductor 44 and a capacitor 46, which tetrode transistor havingianiemittenjacollector, a normal / maybe variable'as, shown to tune the tank circuit to. " base electrode and'an-auxiliary base'electrode, of means the desired harmonic frequency. , for applying energizing" potentials ‘solely tosaidfauxiliar-y, The lower end of the tank circuit 42 is grounded While ‘ base, normal base and‘collectorielectrodes,‘ ar'?rs't; fre its upper: end is coupled through a capacitor 48 to the quency determining circuit" for said oscillator connected,’ collector 14 of the transistor 8; The circuit illustrated with said collector electrode and-tunableifor response to in Figure 2 is'in other'respects identical to the circuit an oscillator signal of a predetermined‘fundamental fre illustrated in Figure l and is operative in substantially quency, a second frequency determiningicircuit; for said § the same manner and with similar advantages. It can oscillator coupled with, the junction ofsaid ?rstifre- " berused in‘ those applications where oscillator signals quencyi determining circuit and'said; collector electrode of even a higher frequency than those obtainable by andr'tunable for response to van oscillator signal'of a ihar-, ‘ the circuit of Figure 1 are desired. The harmonic fre monic frequency of said fundamental! frequenc-yg and’. quency signals so generated may be coupled from the means providing a negative resistancecharacteristic-forV inductor 44 of the harmonic frequency tank'circuit to said- transistor over a portion'of its'op'eratiinggrange in an output circuit. In order to accomplish this a cou eluding said'?rst named means and a capacitor connected ; pling winding 50 is provided which is inductively cou from said emitter electrode to the’ junction of?'saidcolé pled to the inductor 44 of the harmonic frequency tank 50 lector ‘electrode and i‘ said first frequency determining circuit 42. ' circuit. 7 . ' ' ~ Oscillator circuits constructed in accordance withthe " ' 5; In a very high frequency sine-wave oscillator ‘circuit’ teachings ‘of this invention require a minimum number including means providing ;a point of reference'potential ' of circuit components and relatively simple circuit con therein ‘and a'tet'rode transistor having,;a_co]lector,"*an , ‘ nections for generating high frequency oscillations. emitter, a normalbase andaniauxiliaryi,base;electrode;' Accordingly, the invention provides oscillator circuits the' combination comprising; means ’ providing ,, a. ?rst particularly suited forhigh frequency circuit‘ applica source of energizing potential_connected,between' saidf tions Where circuit simplicity together with reliable an auxiliary base electrode Vandysaid point of reference‘rpoé' stable circuit operation are required‘ or desired. tential, means connecting said normal base electrode with What is claimed is:v f ' V said point: of reference potential, a ?rst frequencydeter-fv 11. A high'frequency sinelwave oscillator circuit com mining parallel resonant circuitfconnected’with=said col-1; ‘ prising, in combination,’ a semi-conductor device having lector electrode 'andytunableto a predeterminedifunda- p a..collector, an emitter," a‘normal base andianr auxiliary mental, oscillator frequency, means--providingfa'second1 . base:‘electrode,v means .for applyingenergizing potentials ‘ source of energizing potential connectedybetweenfsaid solely to said .Vnormal. base, auxiliary base, and collector ' ?rsterence frequency potential, determining. said ?rst andsecondsources' circuitand ‘said ‘point of energizi", of"ref-~; electrodes to provide a negative‘resistance characteristic in the collector circuit of said semi-conductor device, ing potential being etfective’to'apply biasing ivoltages a frequency determining v,circuit'connected with said col solelyelectrodes‘ to said to‘provide collector, a negativeiresistance‘characteristicnormal base, .and auxiliaryba'se 5 lector electrode, and a coupling capacitor connected be- . tweenrsaid emitter electrode and the. junction of said in the collector’circuit ‘of said tetrode.iransistonlasecondi ‘ collector electrode and said frequency determining circuit. frequency 7 determining parallel re'sonanbcircuit coupled' 2. In a high frequency ,oscillatorcircuit to the junction of said collector electrode and said'?rst -including means providing’ a point of referencepoten=~ frequency determining parallel resonant circuit?and:tuna-j- tial thereiniand a tetrode transistor having a collector, ' ble'to a harmonic-frequency of-said fundamental 505611-11 an emitter, a normal base and an auxiliary base elec- ' lator frequency, means enhancing said negative /1’6‘S1St— 2,824,901; 5 6 mice characteristic for said transistor over a portion of quency determining circuit connected with said collector its operating range including a capacitor connected from electrode and tuned to a predetermined fundamental said emitter electrode to the junction of said collector oscillator frequency, a second frequency determining cir electrode and said ?rst frequency determining parallel cuit capacitively coupled to the junction of said col‘ resonant circuit, and output circuit means coupled with lector electrode and said ?rst frequency determining cir said second frequency determining circuit for deriving cuit and tuned to a predetermined hannonic frequency therefrom a sinusoidal output Wave at a frequency deter of said fundamental oscillator frequency, and, a coupling mined by the resonant frequency of said second frequency capacitor connected between said emitter electrode and determining circuit. the junction of said collector electrode and said ?rst fre 6. A harmonic generator comprising, in combination, a 10 quency determining circuit. four electrode semi-conductor device having a collector, an emitter, a normal base and an auxiliary base electrode, References Cited in the ?le of this patent means for applying energizing potentials solely to said “High Frequency Transistor Tetrode,” by Wallace et 211.: auxiliary base, normal base, and collector electrodes to pages 112-113 of for January 1953. provide a negative resistance characteristic in the col 15 “Commercial Tetrode Transistors,” page 83 of Tele lector circuit of said semi-conductor device, a ?rst fre Tech and Electronic Industries for May 1954.