US 2352455 A
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June 27,1944. H, R'SUMMERHYES, JR' 2,352455 FREQUENCY MULTIPLIER Filed Sept.. 3 0. 1943 Q a Tm oe vm. @mdp QU. v5 A TmR .Mw WH m H w eines-iba cri tai accetta-'iai Patented June 27, 1944 i `assigner to General Electric Companygfa'corl por-atonoftN'ew York e Application september 30, 1943,. serial.. 5043er/ My' intender-relates to.. frequency multipliers and ilfiorei Daltililarltf @apparatus-.ier obtaining frequency multiplication .and ampliiieatiori--; by
utilizing ielatirely low; frequency crystal osenlators. f
it; isfarn.- object; ofii multiplier;
iniptei'fed .arrangement ,for maintaining stable. i
Oneratien 0f.. thef.f.m111tii21ierf, with yrelativelylcwf crystal excitation.; Y j K, It ancthercbieatzei my inifeiiticn-.to-nroride.A a .frequency multiplier-minimising anl ainnliner: aiidircneiict tripler- .ircuits and.: anrecieved arrangement-ier .diritta feedback of enerex atgthe desiredi ii for increasinrtneeute- Ptit i.nteneiitrrt while .maintaiiiins the. required. low crystal e2'z` ':'tationy necessary toI insureL-'stablej op@ eration.
i The ffeatures of myinvention Whichgl AAbelieve' tibip novell are setvforthwith'particularityiir thfaPDendedclaim-1s.Y A y ever, both. as to itsorganization and# method" of operation, together with further'ebiectseandeada vamagesthereof., may vilcestoe understood ref--A My invention 'itsel-fj hour-.i 3
erenceto .the followingdescription Vtakei'i'eih vcon'-4 nection with.- the accompanying-drawingein'Which- Fig. 1 diagrammaticallyfrepresenta-one formv of frequency inuitiiilierAv circuit; embodying.: ve. ien; .Fiefsiiand re'riresent equivalent ein..v Cit diaerame;e'fltlie .uitshownin Fie., 15, and` Fi'iiisa. Yee'tcr diag 'lius'trating merope. atieiipfniepireuirg l Referring iiQW to .Eeifh the. frequencyi inultif..
pilier 'circuit hasbeenllliistrated asrafhar multiplier' of a' general tpefwei'ilrnpn: in,` art Ari electron discharge; device,- 10; having: an
mais resister. l.; 'o l1.111, the output@ :f 0`between the anode I I4 and the 55 cathode I3 therefare;connected a parallel circuit I6 comprising an inductance I1 and a condenserv I-8,-a.p.ara11el circuiti-2in' comprisingan.inductance ZI;` and nga. condenser. 2 2; and: ai suitable battery or other; source, ofc direct :.current.. potential; mi Thegfirst. Circuit |161.' is .-tunedi to 1 afrequency above but; near. thee natural;.frequencyP ot .the crystal and the; secondttuned l circuit 20. which. consti@v tntesmhe harmonicy multiplier. 'ist preferably tuned tog'aneodd; `harmonic.4 of. the; fundamentarfre--V quency.; If the. circuit.l .tiwere .tuned to:` a.. ire'a quencyi very; near` the natural frequencyv ofthe crystal; :tofzobtairr .urna-Ximum.y output, ouereexcita.-
tionandiiuj-um orgdestructinnoffthecrystaltmight result and stable; .operationi-y the; requiredl treqmncy .Wouldehe impossible;. Ittisi for this rea-A "lia .the circuit..|36; isznotf.tuneditdproiride buteisftuned toiarequencyi suf'-k iiciently ahoyeithematurat' frequenciesothatthe exciiiatiorrof: theecrystale is@ reduced and? stable @eration insurcda.' .'ihtr` propere: adjustment. of this?. itx-Def 'or clioutandi the`r marinergirr lwhich. it Operates; areg :Welk krimi-Z111 im theiart.: :'Ihe. grid. mail@ .llcsistoie .andrtljre-.capacii;iles: associated there.. withtioigierraimple; ,thehcapacitw of; the crystal anriftlie-gridrtmcathode .capacity yofcthe .device,y 1.0i
aim-selected.so.ithatiainegatiuezbias existsom thev glidi.. lill fantil Qllalyniimstivervoltage: peaks.- cause 1 anodefcurrentit 4flows; .tnef .ware fform; of; the theretorexri'chfin harmonics Ei` SJircutiiZsQsQiHa-tesc at.- the.. multiple Adamen-tai. lfrequency tol -whicimi-i; lis t fW''; hefllnderstood .thatgtha tumngot the circuitsf-I tandem depends notonlw emthe apacitieszothe .condenserse l;8;;.an`d,22 leutz also Qltfthsctlzicranigaities y'which arejnherently preseI ent,L th. destine,-l..ll;;;- 1t nature; .voltaefaapnearine across: the llffiszconnled; to; .theeinput .circuit-:ot an electron discharge device'shaying'ianc anode. Zei-...a contrat el.entr-cdc;1zii:anni.areathoclev 2e; .the eircuitz21l-beingicounleiir the griet zsftmoughia Smde reirsfnce .28'.1... .A tunedf; cir:-
ge 2111i iliidiltance.- 33|) 'andzas vara-i aiconnectediirrzloarallei lis corr-i netted thema-tent circnitnirtne deyieeiiaztef... iwlritalli 851:10@ @,alldgthes Cathode; Zizin; series Watters.: 33;. circuit; l3i) isi .tunect Reefer,abi-y;rv tol `ani oddi harmonic: of:` .the-L frequency offV .theecircniti 211,: fori. examp1e-,. the: thirdil har-f monic. The; timel constant ortheeresis'tanceaanda Qaicitycfcombnation. ,comprising lthe re'sistarliccL 28 and capacitance 21 is chosen so that a negaof the apparatus through a suitable coupling condenser 34. The devices I and 23 thus perform the functions of an oscillator, an amplifier and a frequency multiplier. M Because .ofthenecessityf of maintaining relativelyff 10W excitation of the crystal the high frequency energy available at the output of the multiplier must be relatively lowvx provided stable operation is to be obtained. The
high frequency output of the tube -23 r'nay-beil increased by feeding back energy ,from itsoute put circuit to its input circuit,` andI.'liavefound' that this may be accompusiied efliciruywith a minimum number of additional circuit elements by employing an inductancef35 connectedin sel'- A greatly ".Ili-L..
ries with the control grid 25.
creased high frequency output may be obtained by the circuit when providedfrwitnithis induct i The manner in :which: theninductance3 5t'op-l eratesto provide the feedbackcf :energy atthefrequency of. the circuit l3|) may treadily `beunder stcodtfrom the equivalent circuit diagrams of Figs.
2 and3 and the vector: diagram of Fig. 4.; `In Fig.l 2t the impedance of allsthecomponents of the circuit ofFigl lWhichy are'connected betweenI the input'of the impedance 35 and ground have been represented by a capacitor 3l.' .c Fig. 2` is. drawn withlreference -to thethigh frequency appearing across theoutput circuit and'the-circuitsil and y20 which aretuned tomuchlowerfrequem' cies. present a capacitiveY reactanceiat the-high frequencies; this' assumptionlneglects the resist:- ance losses which arel relatively unimportant. The. impedance of. the "devices I 0 is also essentiallya. capacitive reactance. in paralleliwith -a AAhigh resistance.. tAllithese. capacitive reactancesk have beencombined and represented by' the capacitor- 3l.I y .The capacity indicated` in 'dottedlines atl-38 represents the Janode togridi'capacityof the de-f vice l23 and: capacities betweensthe associated` leads. The inductance v'is selecteditorhavea value such that f whenf it=.is; combined in series Withithe condenser 3`|vthe resultant-'reactancewilll berinductive andof the orderfofone-twentieth-of the reactance of theV gridl tocathodef capacity lof a voltage Eg' is developed bythe current Ig across the inductance 40 and leads the current by 90; the voltage Eg' therefore is 180 out of phase with Ep. Since the parallel circuit 30, taking into account the other impedances associated therewith in the anode circuit, is tuned to resonance, it pre- 'sents a resistive impedance to the voltage Ep, and Ep is, therefore, 180 out of phase with Eg. The voltage Eg andthe feedbaclcyoltageyEgf'are thereforel'in i` h a's"e,fwhich is thecbndition 'required for regeneration. It will be found that as the effective inductive reactance 40 is increased as by inwcreasisng the inductatice 35, the feedback of energy y"-f-rr'n 'the output to the input of the device 23 is i increaseduntil a value of the inductive reactance reacl'ifedatWhifch self-oscillation of the cir- .Occurs It ist of course, desirable to avoid self-oscillation and for this reason a value of inductive'-reactanceless` than that which produces self :oscillation is selected. The increase in output produced by a value of inductive reactance below the value for. self-oscillationl isls'tillV very substantiall and? .makes it possible A to operate the circuit withI `the' ifr'elatively: ilow excitationL 'of the crystal which is necessary to insure frequency stability. Greatly increased output at the high harmonicv frequency may thus be obtained. *if y It will beeVident/that myl invention provides a structurally simple and *effective "frequency multiplying circuit-with a minimum -number of circuit components. By proper selection 'of theV feedback impedance 35,- high efficiency `v`and jsta- I bilityv .are attained'l togetherf-With amplification I Without the rnecessity 'ofl increasing'f the crystal excitation.' *By Way ofillu'strationcnly, and' not i by way of limitation,f-there'arelisted below values of vcircuit constants which' have been found-"toi besuitable foi-'the circuit Aof" Fig. 1 when employed in--azparticular frequency multiplier in which the harmonic circuitsV 20 'and 30l Were'tuned to" the third -Il.ia'r-monic fof thefunda'mental frequency and -tlffe frequency ofthel circuit 20, "respecthe device23lindicatedat39m Furthermore,
combination. circuitl comprising'l the in'ductanc'ez and icondenser, 31 in series yshunted"byf'thej cathode capacity 39 has an; effective Jinductive reactance which maybe representedby'arix iii-Jy ductance 40, as indicated-in Fig. 3-. Furthermore; since the grid. to` plate and y1 the grip-to cathodel capacities of a threeeelement tube,'lls`ruchrlas thedevice 23, are always of the same order of lmagni-f tude, the inductive reactance 40 ofthe-order of one-twentieth the: capacitive;-reacta'ncer ofithe plate togrid capacity 38.
- yThel vector l`relationships ofi the? voltages and currentsinFig. 3 are indicated-in Fig. 1r-these vectors. are shown 'with -respecteto'r their relative' phase .relationshipbutnotlfnecessa'rily jwith -rel spect to theirmagnitudes. `'The-'vector E'psrep'revsents the;anode .voltagecf the-'device' 23.
voltagecauses a current representedby the-vector- Ig; to flow through Athe seriescircuit'includingfthe capacity38 and-the effective inductance-lllt).Y The current Ig leads the voltagerEp by`90 because theL branch .of the. anode-:cathodeA impedance: lcon-t sisting ofthe' capacity'38 and inductance-dinf serieshas an effective capacitiverreactancey," andlWhat 'I claim as" new' 22 were 5 to 25 M tfd. air trin'inier p'acitors 'ha ysatisfactoryv value-vof the `inductance'35f':was "foundto` beV ap'p`rd'nximatelyI 0.41-micrcheriry. The crystal @oscillator frequency was17i372megacyclesi The direct current potential pfthe'sources 9 and'33 an input circuit tuned to a fundamental frequency and connected between said cathode and said control electrode, an output circuit tuned to a harmonic of the fundamental frequency and connected between said anode and said cathode, said input circuit being capacitive at said harmonic frequency, means providing a negative bias for said control electrode whereby only positive wake peaks at said fundamental frequency render said device conducting, and an inductance connected in series between said control electrode and said tuned input circuit for providing regen-` erative feedback of energy at said harmonic frequency.
2. A frequency multiplying apparatus comprising a crystal oscillator, a circuit in the output of said oscillator tuned to a predetermined frequency, an amplifier comprising an electron discharge device having an anode and a cathode and a control electrode, the control electrode to cathode circuit of said amplifier being connected to include said tuned circuit, an output circuit for said amplifier connected between said anode and said cathode and tuned to a harmonic of the frequency of said rst mentioned tuned circuit, the input circuit of said amplifier being capacitive at the frequency to which the output circuit thereof is tuned, means providing a negative bias for said control electrode whereby only positive wave peaks at the frequency of said first mentioned tuned circuit render said device conducting, and an.- inducta'ncel connected in series between said control electrode and said first tuned circuit for providing a regenerative feedback of energy at said harmonic frequency.
3. A frequency multiplying apparatus comprising a crystal oscillator vincluding an electron discharge device having a piezoelectric crystal connected in the input circuit thereof, and a. first circuit tuned to the fundamental frequency of the crystal connected in the output circuit thereof, a second tuned circuit connected in the. output of said device and ltuned to a harmonic of said fundamental frequency, an amplifier comprising an electron discharge device having an anode and a cathode and a control electrode, the control electrode to cathode circuit of said amplifierbeing connected to include said second tuned circuit, an-output circuit for said amplifier connected between said anode and said cathode and tuned to a harmonic 'of the frequency of said second tuned circuit, said second tuned circuit being capacitive at the frequency to which said output circuit is tuned, means providing a negative bias'for said control electrode whereby only positive wave peaks at the frequency of said