Order this document by MC1495/D I MOTOROLA MCI 495 I I Wideband Linear Four=Quadrant Multiplier The MC1 495 is designed for use where the output is a linear product of two input voltages. Maximum versatility is assured by allowing the user to select the level shift method. Typical applications include: multiply, divide*, square root*, mean square*, phase detector, frequency doubler, balanced modulator/demodulator, and electronic gain control. Excellent Linearity: 27. max Error on X Input, 47. max Error on Y Input Over Temperature@" .J*::,!:, 1YOmax Error on X Input, 2Y. max Error on Y Input at + 25C ` +:*} .', \'t~+$, ,>.:\:*. Adjustable Scale Factor, K ` ``i'$i}, ,is(i:+>,. .*.,.. ,` Excellent Temperature Stability ;$ .,:,. ;,. .+\ *~; \m,,3r&\.+ Wide Input Voltage Range: t 10 V .:~. f>. , s, ,,.$;,. ..,}+:,:,, !<,.,,.+,., +15 V Operation ~:\.,:,\ I D SUFFIX PLASTIC PACKAGE CASE 751A (s0-14) 1 1 INGS ~"'~l-va,V12-V7, (TA = + 25C, unless othewise P SUFFIX PLASTIC PACKAGE CASE 646 noted.) Symbol Value Unit AV 30 Vdc v12-vg v4-v8 f (6+113 Rx) * (6+13 Ry) Vdc 10 10 mA 1, V1-vg, V1-V,2, V,-V4, vg-v7, V8-V7, V4-V7) Differential Input Signal Maximum Bias Current 13 113 Operating Temperature Range Storage Temperature Range Device TA MC1 495 MC1495B ORDERING INFORMATION `c 0 to +70 - 40 tO +125 Tstg -65to +150 Tested Opereting Temperature Range MC1495D Package so-1 4 TA = 0 to + 70C MC1495P Oc MC1495BP Plastic DIP TA = - 40 to +125C 0 Motorola, inc. 1995 Plastic DIP MC1495 ELECTRICAL CHARACTERISTICS othe~ise noted.) (+V = + 32 V, -V = -15 V, TA = + 25C, 13= 113= 1.0 mA, RX = Ry = 15 kQ, RL = 11 kQ, unless Figure Characteristics Symbol Min -ineaflty (Output Error in percent of full scale) TA = + 25C -lo<vx<+lo (vy=*lov) ,. -lo<vy<+lo (vx=*lov) TA = TLOWtO THigh -locvx<+lo (vy=flov) -Io<vy< +lo(vx=tlov) 5 Square Mode Error (Accuracy in percent of full scale after Offset and scale Factor adjustment) TA = + 25C TA = TLOWtO THigh 5 Scale Factor (Adjustable) -- K -- Input Resistance (f= 20 Hz) 7 RinX Riny - Differential Output Resistance (f= 20 Hz) 8 RO - Input Bias Current 6 ( ,bx =(lg -- + 112) 2' K= 2RL TA = + 25C TA = TLOWtO THigh Input Offset Current llg-1121 114-181 6 TA = + 25C TA = TLOWtO THigh Average Temperature Coefficient of Input Offset Current TA = TLOWto THigh Output Offset Current 1114-121 TA = + 25C TA = TLOWto THigh ERX ERy - tl .0 * 2.0 *1.0 * 2.0 ERX ERy - *1.5 * 3.0 t 2.0 f 4.0 -- * 0.75 -- *1,0 ESQ Unit > "?* ,+!$ ..:<!+ :s:~+:>:., ., ,y';;&>a: .:., js `~::j ~S>, #,,,~.>, ~ ,,. ~~:~$ `~' --,,??.:\. `~:f;,,, "+$ ;?;..,:i$$ ,~r ~:.-~. .,:! ,:~~, ,.:* ` . ..*,*, `~$~.>$:s' .,. ..',.>*+>\ ,,* ,:'.:..,, S$ ..,~:.k ,~} \,~ ~, `.,., . - 3@*k\;~., ~'*&$ "" 0.1 ,;;>$~p \ %.,:s+,! , `~ *'rj*i,i,.,<.,, . `\ ,~ ~, ~~ 2.0 Ibx, Iby ..3:. .. .*$, .gcvq,. 2.0 ., ,. {.,!~,)),, ,.~ j.. `::J$, ,,~ .,,. .,,?> .... .,,:",,*, ,~,:.,+:~ ~..,, ;$$." Il\Qxll?$;l 0.4 -- ,13:;! ,, 0.4 ,., ., I?*[iOl 6 ~f*:`+$% ?: .~.~`*y<,,\:j.. e~'~~ `"' 11001 .:,.., Average Temperature Coefficient of Output Offset Current ~i/ 6 .). `\\&*, \ ,, TA = TLOWtO THigh ~!.+ ,.,:, .?, . \N~>~\+l ,,;`*/., !....... ..*. ::1~ Frequency Response 9,10 ,,}.." ,.},$3 "..,. t., ,.< 3.0 dB Bandwidth, RL = 11 kQ .s:>,,..., ~ 3.0 dB Bandwidth, RL = 50 Q (Transconductan@,@~@ dth) .,.,\ "~:. +?;\J.,, ``~ 3 Relative Phase Shift Between VX and VyWJ:Y@,.+ 1YeAbsolute Error Due to Input-Output Ph~~i~~~ sty~ ,? Common Mode Input Swing .s$,.' * ,,$ *~\*. 11 .~:~ t:,~, (Either Input) .,,. ~t), ;? ~~:' ~':+~. Common Mode Gain 11 TA = + 25C .+. (Either Input) ~a,~~$$~~ TA = TLOWto THigh Max 0/0 13 RxRy ) l~y=y (14 + 18) Typ - Mfi kQ PA 8.0 12 pA 1.0 2.0 nNOC -- 2.5 -- -- 10 20 50 100 lTCIOOl PA nN"C 20 - -- 3.0 80 750 30 -- -- -- -- *1 0.5 *12 -- ACM - 50 - 40 -60 -50 -- -- dB Vdc BW(3dB) TBW(3dB) fq fe CMV MHz MHz kHz kHz Vdc Common Mode Quiescent i'r$~$f$ .(.\" ~,;;.~ Output Voltage Y;si~$ 12 Vol V02 - 21 21 -- -- Differential Output,~o$~&~wing Capability , ,., 9 Vo - +14 -- power SUPPIY*~%ti& . .::, ,,,,,.Jj:>ji .<>,\ 12 s+ s- _ - 5.0 10 -- -- 12 17 6.0 7.0 mA 12 pD 135 170 mW Power S*pl~&urrent ,,`b,.,.t.. DC @m;Dssipation k,,,, \ ..... . ,J>. ~wt. THigh= +70CfOr MC1495 `$; 2 =+1 25C for MCI 495B - vpk mVN TLOW= OCfor MC1495 =- 40C for MC1495B MOTOROLA ANALOG IC DEVICE DATA MC1495 Figure 1. Multiplier Transfer Characteristic Figure 2. Transconductance Bandwidth -8.0 -in 2 Output (KXY) 14 9 Y Input X Input 12 11 10 . .. >-.. .- < `#l* 5.0 k Scale Factor Adjust y_ _ -- $0.tpF -- MOTOROLA ANALOG [C DEVICE DATA Onset Adjust 10k ~ -- I A i 4 1 -15 v NOTE: v. Adjust "Scale Factor AdjuaV for a null in VE.ThiS schematic for illustrative purposes only, not specified for test condtions. 3 MC1 495 Figure 5. Linearity (Using X-Y Plotter Technique) Ry=15k ** Rx=15k m t32v T Figure 9. Bandwidth (RL = 11 kQ) Ry=15k Rx=15k t32v 4 ein= 1.0V~S q" 1 9.1k 2 = llk -- Scale Factor 4 MOTOROLA ANALOG IC DEVICE DATA MCI 495 Figure 11. Common Mode Gain and Common Mode Input Swing Figure 10. Bandwidth (RL = 50 Q) o Ry=510 Rx=510 t15v 4 q" = 1.0 Vms (i l.Ok , 2 MC1495 ) 50 ; ) 50 13 -- -- -- 3( 7 R13 13,7k 12k K=40 1 Scale Factor 5,0 k -- 0,1 pF I T= * a~o"'~F eO CL< 3.0 pF I Figure 12. Power Supply Sensitivity +32V --- 15k +32 V (V+) e 15k 2,0 k 4 -- v'" 9.1 k I 9 4e 2 11 k Pot #2 ~ 2.0 k 6.2 V () m `% ~ 0.1 pF To Pin 12 X Offset A~ust AA. tt 2.0 k -- 10 k 1 -15 v Figure 14. Offset Adjust Circuit (Alternate) Vt ! R a To Rn 8 Pot #1 Y Offset Adjust 10k I 5.1 v Pot#2 10k T ~ I To Pin 12 x offset A~ust I & -15V MOTOROLA ANALOG IC DEVICE DATA 5 MC1 495 Figure 15. Linearity versus Temperature Figure 16. Scale Factor versus Temperature 2.0 ~ z ~ 0.110 1.6 \ \ ~ a y 1,2 0 5 ~ WC 0.8 + ~ 1.4 \ E 0.105 K Adjusted to 0.10 Oat 25C 0,100 x- % 0.6 w 0.4 0.095 0.2 0 -55 -25 0 25 50 75 TA, AMBIENT TEMPERATURE PC) 100 125 -55 -25 0 Figure 17. Error Contributed by Input Differential Amplifier o -4.0 6.0 8.0 10 12 14 Rx or Ry (k Q) IVII or IV71 (V) 6 MOTOROLA ANALOG IC DEVICE DATA MC1495 OPERATION AND APPLICATIONS Theory of Operation o The MCI 495 is a monolithic, four-quadrant multiplier which operates on the principle of variable transconductance. A detailed theory of operation is covered in Application Note AN489, Analysis and Basic Operation of the MC1595, The result of this analysis is that the differential output current of the multiplier is given by: 1~-lB=Al=R3 where, 1A and IB are the currents into Pins 14 and 2, respectively, and VX and Vy are the X and Y input voltages at the multiplier input terminals. DESIGN CONSIDERATIONS General The MC1 495 permits the designer to tailor the multiplier to a specific application by proper selection of external components. External components may be selected to optimize a given parameter (e.g. bandwidth) which may in turn restrict another parameter (e.g. maximum output voltage swing). Each impoflant parameter is discussed in detail in the following paragraphs. Linearity, Output Error, ERX or ERY INFORMATION 3 dB Bandwidth and Phase Shift Bandwidth is primarily determined by the load resistors and the stray multiplier output capacitance and/or the operational amplifier used to level shift the output. If wideband operation is desired, low value load resistors and/or a wideband operational amplifier should be used. Stray output capacitance will depend to a large extent on ,*!. `*{,1, circuit layout. >.,:;,,<*, >,.\~q.\\ Phase shift in the multiplier circuit result~~f,m" Iwo sources: phase shift common to both X and Y:~am~@ls (due to the load resistor-output capacitance,:$~~Wentioned above) and relative phase shift betweep ?M:&'MY channels (due to differences in transadmitta~~$? i~!he X and Y channels). If the input to output p~~w~ is only 0.6, the output product of two sine wavqs %,,$hibit a vector error of 1YO.A 3 relative phase shift ~~eefi~x and Vy results in a vector error of 50/.. ,,.a<~$j;~ix .'~.v:),j Maximum Input vO[t~#~~~.,+V VX(max), vY(m#~&~@,df voltages must be such that: ` `~.t.., N],v ~~(max) c113 RY ..w~`~~~-'''"" $$,,::,> Vy(max) <13 Ry ExceedJ8~~i$jaiue will drive one side of the input amplifier to "cuti&'hnd cause nonlinear operation. ,,$&urre* 13 and II 3 are chosen at a convenient value ,@~~b~~ing power dissipation limitation) between 0.5 mA and tinearity error is defined as the maximum deviation of $+,2.% mA, approximately 10 mA. Then RX and RY can be output voltage from a straight line transfer function. It i~..~$: .~J{':*terMined bY considering the inPut si9nal handling .:4.<< $$W expressed as error in percent of full scale (see figure below). `-?h requirements. For VX(max) = Vy(max) = 10 ~ RX= Ry>l;;;A ---l - OkQ. 2VX Vy The equation 1A- IB = -- Rx Ry 13 2VX Vy is derived from 1A- IB = (Rx +%3 Iil: ) (Ry +~) IS `:."$. For example, if the m@wdeviation, VE(max), is +100 mV and the full ..s?~~<$%utput is 10 V, then the percentage error is: $J~s~ - 2kT 2kT and Ry >> -- with the assumption RX >> -- q13 " ql13 At TA=+25C and 113= 13= 1.0 mA, 3T=*T=52Q. ql13 q13 ~nearit~~~f maybe measured by either of the following methq.~$$~<,`"~ ,~.... , `{'3 ,,Y~,:~i@ an X-Y plotter with the circuit shown in Figure 5, ~~~f.~~@tainplots for X and Y similar to the one shown above. ,,,~,. >\\, ,>.*>, ~i$?%j2.Use the circuit of Figure 4. This method nulls the level ,!,i~,, shifted output of the multiplier with the original input. The :,' peak output of the null operational amplifier will be equal to the error voltage, VE (Max). One source of linearity error can arise from large signal nonlinearity in the X and Y input differential amplifiers. To avoid introducing error from this source, the emitter degeneration resistors RX and Ry must be chosen large enough so that nonlinear base-emitter voltage variation can be ignored. Figures 17 and 18 show the error expected from this source as a function of the values of RX and Ry with an operating current of 1,0 mA in each side of the differential amplifiers fi.e., 13= 113= 1.0 mA). MoToRoti ANALOG ICDEVICE DATA Therefore, with RX= Ry = 10 kQ the above assumption is valid. Reference to Figure 19 will indicate limitations of VX(max) or VY(max) due to VI and V7. Exceeding these limits will cause saturation or "cutoti of the input transistors. See Step 4 of General Design Procedure for further details. Maximum Output Voltage Swing The maximum output voltage swing is dependent upon the factors mentioned below and upon the particular circuit being considered. For Figure 20 the maximum output swing is dependent upon V+ for positive swing and upon the voltage at Pin 1 for negative swing. The potential at Pin 1 determines the quiescent level for transistors Q5, Q6, Q7 and Q8. This potential should be related so that negative swing at Pins 2 or 14 does not saturate those transistors. See General Design Procedure for further information regarding selection of these potentials, 7 MC1495 Figure 20. Basic Multiplier GENERAL DESIGN PROCEDURE ~ Rx 9 "x {: "y 12 :" `4, l:i v+ Ry `RL t tQ 14 .t MC1495 RL 2 . `,, , Vo Selection of component values is best demonstrated by the following example. Assume resistive dividers are used at the X and Y-inputs to limit the maximum multiplier input to ~ 5.0 V [VX = VY(ma~)] for a * 10 V input [V~"= V~(max)] (see Figure 21). If an overall scale factor of 1/1 O is desired, =:1 - then, VO= Vy Vy ~= (2VX) (2VY)= 4/1o Vx VY ,0 ,:!$, 3 13 t 13 R3 7 VO=KVx K=-- sg:.;y.;:<ti, Vy 2RL Rx Ry 13 R13 `~ "- If an operational amplifier is used for level shift, as shown in Figure 21, the output swing (of the multiplier) is greatly reduced. See Section 3 for further details. ,(,. ~,. ~ ,:,.. Therefore, K = 4/10 for the multiplier (excluding t~~$~J&~r .,. ".*... ~ network). .<:x {L ~ :..$? ....1. Step 7. The fist step is to select current 13,@&~~:@ent 113. There are no restrictions on the selectionA~:,@fiher of these currents except the power dissipation of,~e~~~e. 13and113 will normally be 1.0 mA or 2.0 mA. Furth'&{x~$ does not have to be equal to 113, and there is &&ily no need to make them different. For this exampl$'h$t~ ., -"x "y 10 -- =T-'5V `"v+ ,. 8., MOTOROLA ANALOG IC DEVICE DATA ~ MC1495 To set currents 13 and 113 to the desired value, it is only necessa~ to connect a resistor between Pin 13 and ground, and between Pin 3 and ground. From the schematic shown in Figure 3, it can be seen that the resistor values necessary are given by: R13+500Q='V-';7V R3 +500 Q ='v-' Let V-=-15V, then R13+500=-- ~7 13 v voltage. It should also be noticed that the collector voltage of transistors Q3 and Q4 is at a potential which is two diode-drops below the voltage at Pin 1. Thus, the voltage at Pin 1 should be about 2.0 V higher than the maximum input voltage. Therefore, to handle +5.0 V at the inputs, the voltage at Pin 1 must be at least +7.0 V. Let V1 = 9.0 Vdc. Since the current flowing into Pin 1 is always equal to 213, the voltage at Pin 1 can be set by placing a resistor (RI) from *,\ Pin 1 to the positive supply: *'X,l, $J,$<,. ,,. ,'~ ,'$:. `!,.~1+ts., 14.3V or R13= 13.8 kQ 1.0 mA Let R13 = 12 kQ. Similarly, R3 = 13.8 W, let R3 = 15 kQ However, for applications which require an accurate scale factor, the adjustment of R3 and consequently, 13, offers a convenient method of making a final trim of the scale factor. For this reason, as shown in Figure 21, resistor R3 is shown as a fixed resistor in series with a potentiometer. For applications not requiring an exact scale factor (balanced modulator, frequency doubler, AGC amplifier, etc.) Pins 3 and 13 can be connected together and a single resistor from Pin 3 to ground can be used. In this case, the single resistor would have a value of 1/2 the above calculated value for R13. Step 2. The next step is to select RX and Ry. To insure that the input transistors will always be active, the following conditions should be met: M<113, Rx !Y <13 Ry A good rule of thumb is to make 13Ry 21.5 Vy(&a$t,~nd 113Rx> 1.5VX(max).The largerthe 13Ryand 11~%~~juct in relation to Vy and VX respectively, the mord%o~'~rate the *:$* ,.;:..,~, multiplier will be (see Figures 17 and 18). :~$j.~:,,.$y RI = 3.o ~. "$$,$ ~>$*\ . ,.:~~ ,\\,~\ Note that the voltage at th@Y@~>of transistors Q5, Q6, Q7 and Q8 is one diode-dro,@~$@d*the voltage at Pin 1. Thus, in order that these transi~~~l$~y active, the voltage at Pins 2 and 14 should be apWMately halfway between the voltage at Pin 1 and the@#]tlv&supply voltage. For this example, the voltage at Pin#i:@ 14 should be approximately 11 V. Step 5. {~o~ti~'applications, such as the multiply, divide and sq~dr~~tit functions, it is usually desirable to convefl the ..di#~ntial output to a single-ended output voltage re@;~nced to ground. The circuit shown in Figure 22 ,:*OFMS this function. It can be shown that the output voltage ,:+,,~t~f~Kis circuit is given by: ..... t<< .. VO = (I2 -114) RL 21X Iy 2vxvy And since IA-16 = 12-114 = -- -- = 13RxRy 13 then VO = 2RL Vx' Vy' 4Rx Rx 13 where, VX' Vy' is the voltage at the input to the voltage dividers. Figure 22. Level Shift Circuit Vt T 12< + RO V2 RO t Vo V14 * 1144 + Sf~.k## ?O determine what power supply voltage is n~~~,g~~ fOr this application, attention must be given to the ~,g{;~$r''schematic shown in Figure 3. From the circuit ?Wrnatic it can be seen that in order to maintain transistors ~1, Q2, Q3 and Q4 in an active region when the maximum input voltages are applied (VX = VY = 10 V or VX = 5.0 V, Vy = 5.0 V), their respective collector voltage should be at least a few tenths of a volt higher than the maximum input MOTOROLA ANALOG IC DEVICE DATA RL - RL *A ,"" The choice of an operational amplifier for this application should have low bias currents, low offset current, and a high common mode input voltage range as well as a high common mode rejection ratio. The MC1 456, and MC1 741 C operational amplifiers meet these requirements. 9 MCI 495 Referring to Figure 21, the level shift components will be determined. When VX = Vy = O,the currents 12and 114will be equal to 113, In Step 3, RL was found to be 20 kQ and in Step 4, V2 and V14 were found to be approximately 11 V. From this information RO can be found easily from the following equation (neglecting the operational amplifiers bias current): v+_v2 ~.+lq3=-- RL And for this example, fiQ+ ,,, :. RO 1.0 mA= 15 V-11 v RO Solving for Ro: RO = 2.6 kQ, thus, select RO = 3.0 kQ For RO = 3.0 kQ, the voltage at Pins 2 and 14 is calculated to be: V2=V14=I0.4V, The linearity of this circuit (Figure 21) is likely to be as good or better than the circuit of Figure 5. Further improvements are possible as shown in Figure 23 where Ry has been increased substantially to improve the Y linearity, and RX decreased somewhat so as not to materially affect the X linearity, This avoids increasing RL significantly in order to maintain a K of 0.1. The versatility of the MCI 495 allows the user to to optimize its petiormance for various input and output signal levels. OFFSET AND SCALE FACTOR ADJUSTMENT Offset Voltages Within the monolithic multiplier (Hgure 3) transistor baseemitter junctions are typically matched within 1.0 mV and resistors are typically matched within 2Y0. Even with. t%, careful matching, an output error can occur. This out~~~~%};$' is comprised of X-input offset voltage, Y-input offse~~o$~gb, and output offset voltage. These errors can b@sa~%&d to zero with the techniques shown in Figure ~J$t*& terms can be shown analytically by the transfer f,~dqh?'" VO = K[VX t ~ox A Vx(off)] [Vy + ~o~{~@~j Where: K Vx Vy ~ox ~oy = = = = = * VOO (1) scale factor,, ~;,. "~w" "x" input,~~&: "y" inptif~o*e "x" i~~~et voltage `(y'~w offset voltage VX(OH) .,p$y" `iihut offset adjust voltage `$w:$$y*input offset adjust voltage ,. }.> ` `t(~~$$~:~utput offset voltage. ,~,,i.. .',*',,,~$., >i,,i,,.,w ,,,+~ Figure 23. Multiplier with lmpro~pd ~~earity -15V -Vx Vy 10 ~2"0k -- ~20k -- 10 MOTOROLA ANALOG IC DEVICE DATA MC1 495 X, Y and Output Offset Voltages DC APPLICATIONS Multiply Xoxffyox:y The circuit shown in Figure 21 may be used to multiply signals from dc to 100 kHz. Input levels to the actual multiplier are 5.0 V (max). Wth resistive voltage dividers the maximum could be very large however, for this application two-to-one dividers have been used so that the ma~{rnum input level is 10 V. The maximum output level has ak'~en -,/,,$::,+: !?\* ..,:>:. ,$$:,,. For most dc applications, all three offset adjust designed for 10 V (max). \> ,.,'''t't,$.: $*. , .,, >.,*. . potentiometers (PI, P2, P4) will be necessary. One or more ..,<,. `.*~~>,,: <x ~~:'.~ Squaring Circuit .,,. "+$?. offset adjust potentiometers can be eliminated for ac If the two inputs are tied together, the rp~&@~function is applications (see Figures 28,29, 30, 31). squaring; that is VO = KV2 where K is @~JscM# factor. Note If well regulated supply voltages are available, the offset that all error terms can be eli~-~~$>~ith only three adjust circuit of Figure 13 is recommended. Otherwise, the adjustment potentiometers, thus, ell~{n,~ng one of the input circuit of Figure 14 will greatly reduce the sensitivity to power offset adjustments. Procedurq~~~{ nti%ing with adjustments supply changes. ~~ ,...:5,, are given as follows: ,,+, ~:-+, `<i:>, ,... ~,.'.,;~,. ..1..,. Scale Factor t$t,.,$~s)' A. AC Procedure: +.$k:,,,.;>'$ The scale factor K is set by P3 (Figure 21). P3 varies 13 1. Connect os@,@,*?~WO kHz, 15 Vpp) to input. which inversely controls the scale factor K. It should be noted 2. Monitor g~tpu$qt ~.O kHz with tuned voltmeter that current 13is one-half the current through RI. R1 sets the and ad~~$~~ for desired gain. (Be sure to peak bias level for Q5, Q6, Q7, and Q8 (see Figure 3). Therefore, to resw.~f the voltmeter.) be sure that these devices remain active under all conditions 3. ~#~}v,@meter to 1.0 kHz and adjust P1 for a of input and output swing, care should be exercised in *ititim output voltage. adjusting P3 over wide voltage ranges (see General Design .,,?~ ~und input and adjust P4 (output offset) for Procedure). ,,* .,.,, "', O Vdc output. Adjustment Procedures ReDeat steps 1 through 4 as necessay. $' "'t$. .,{~,+ The following adjustment procedure should be used to null ". w~ ` DC Procedure: the offsets and set the scale factor for the multiply mode of +t.~!i@. k; A +.,., 1. Set Vx = Vy = O V and adjust P4 (output offset operation, (see Figure 21). \xt+*} ..,,> \ ~otentiometer) such that Vo = O Vdc .%\: :i\.$. 1. X-Input Offset 2. Set VX = Vy = 1.0 V and adjust P1 (Y-input offset (a) Connect oscillator (1.0 kHz, 5.0 Vpp sin~{$~~' potentiometer) such that the output voltage is +~.j ,,4. ` .,,,,~~, to the Y-input (Pin 4). +0.loov. (b) (c) 2. 3. 4. Connect X-input (Pin 9) to ground. t&NJ~@t Adjust X offset potentiometer (P@}$~~~~bc ~ .,:~.,,.'N' .,,.?,:' null at the output. ,,.., "::,+by " Y-Input Offset ].s sinewave) (a) Connect oscillator (1.0 kHr$'Wpp to the X-input (Pin 9):<:,,*~,$~!.w; (b) Connect Y-input (Pin~J t$ground. (c) Adjust Y offset ~~~%~~fi'eter (PI ) for an ac null `3il\f# at the outputi.. Output Offset ~~.g~,l$ " (a) ConneCj @t~~and Y-inputs to ground. (b) Adjup8~M$t offset potentiometer (P4) until th~ ~&@& voltage (VO) is O Vdc. Scqp::%;{ti (a)$,A ,ly +1 O Vdc to both the X and Y-inputs. t~~~%~~?ust P3 to achieve + 10 V at the output. ~$:m;$$peat steps 1 through 4 as necessa~. ,.4,, "~The ability to accurately adjust the MC1495 depends upon the characteristics of potentiometers P1 through P4. Multi-turn, infinite resolution potentiometers with low temperature coefficients are recommended. MOTOROLA ANALOG IC DEVICE DATA 3. 4. Set VX = Vy = 10 Vdc and adjust P3 such that the output voltage is+ 10 V. Set Vx = Vy = -1 O Vdc. Repeat steps 1 through 3 as necessary. Figure 24. Basic Divide Circuit Vy 11 MCI 495 Divide Circuit Consider the circuit shown in Figure 24 in which the multiplier is placed in the feedback path of an operational amplifier. For this configuration, the operational amplifier will maintain a "virtual ground at the inverting (-) input. Assuming that the bias current of the operational amplifier is negligible, then II = 12and, ., RI Solving for Vy, If RI=R2, If Rl= KR2, = vy=-- (1) R2 -R1 VZ -- R2 K VX (2) -Vz (3) Vy = -- KVX Vy=-- percentage error = *I -Vz (4) v~ Hence, the output voltage is the ratio of VZ to VX and provides a divide function. This analysis is, of course, the idealcondition, If the multiplier error is taken into account, the output voltage is found to be: x 100% or from Equation (5), AE R2 [1 `KVx PED = -Vz KVXVy In terms of percentage error, AE RI.I VZ (7) *,\ *'X,l, $J,$<,. ,,. ,'~ ,'$:. `!(:":1+ts., From Equation 7, the percentage error is inversel~~~~~~ to voltage VZ (i.e., for increasing values of VZ, the WJ~@'ge ,,~+, .~,s( ,,? ,* error decreases). `" ~!.,1,~.,~ ` A circuit that performs the divide func{~~r~.,~hown in ~!,.>:y',J.~ Figure 25. ~.'yttti,,' ,,,<,:N.Nt*J *, VZ `. R1 [1 .R2 K. VX Two things should be emphasized con'~n~@gFigure 25. 1. The input voltage (VXI) musk~tgrd~ter than zero and must be positive. This in@$~kat the current out of Pin 2 of the multipliq$~$dl "&ways be in a direction compatible with the ~.~$~bf VZ. 2. Pin 2 and 14 of the%f~lier have been interchanged in respect to th~&&&rat~dnal amplifiers input terminals. In this insta,~~:fi~ure 25 differs from the circuit connectl~Js~Wn in Figure 21; necessitated to insure nega&&f&*ack around the loop. *..7:,, (5) A suadted atiiustment procedure for the divide circuit. l,~~e~.~z = OV and adjust the output offset potentiometer where AE is the error voltage at the output of the multiplier. $ (~4) until the output voltage (Vo) remains at some (not Frornthis equation, it is seen that divide accuracy is strongly ,,8,&~~~:decessarily zero) constant value as V~ is varied dependent upon the accuracy at which the multiplier can be ":~~~ between +1.0 V and +1 O V. set,: particularly at small values of Vy. For example, assume . 2. Keep VZ at O V, set VX' at +1 O V and adjust the Y input $t" that RI = R2, and K = 1/1 O. For these conditions the outpq~,bf offset potentiometer (Pl ) until VO = O V. ,\(.* ~>:~., , the divide circuit is given by: `{Yb, 3. Let V~ = VZ and adjust the X-input offset potentiometer ~~->..:.,> (P2) until the output voltage remains at some (not necessarily - 10 V) constant value as VZ = VX' is varied between +1.0 and +1 O V. Keep V~ = VZ and adjust the scale factor potentiometer (P3) until the average value of VO is-10 V as VZ = Vx~ is varied between +1.0 V and +1 O V. 5. Repeat steps 1 through 4 as necessay to achieve error woltage of the divide circuit,~~.Q# expected to be a optimum petiormance. hundred times the error of theb$i,c;~ultiplier circuit. <$ !~`).Y<>$ I, `~.',.!.~~ ,$s: \!:;,>, ,. ,'j. t15v Rx 10k , 0.1WF Ry 10k 3 t ~ (~? + ~ `" ~F 6 MC1741C MC1495 t 12 + ? 2 VO vo=~ -lo Vz MOTOROLA ANALOG IC DEVICE DATA MC1495 Hgure 26. Basic Square Root Circuit AC APPLICATIONS `Z%zvo L-- or _ Ivzl "0= { y The applications that follow demonstrate the versatility of the monolithic multiplier. If a potted multiplier is used for these cases, the results generally would not be as good because the potted units have circuits that, although they optimize dc multiplication operation, can hinder ac applications. Frequency doubling ofien is done with a diode where the fundamental plus a series of harmonic~,,,are generated. However, extensive filtering is required t~xin the desired harmonic, and the second harmo~~,~$tined under this technique usually is small in ~~~$L@e and ?$7...~, requires amplification. ,~".,m.~ ~,};., When a multiplier is used to double f~~qtiti the second harmonic is obtained directly, exceptq~~~~~pqerm, which can :?$;),~~. " be removed with ac coupling. Square Root e. = KE2 COS2Q~ `$~ `$' ~?:t,i: .J~. A special case of the divide circuit in which the two inputs to the multiplier are connected together is the square root function as indicated in Figure 26. This circuit may suffer from latch-up problems similar to those of the divide circuit. Note ,+.f>$v~ji, ~" that only one polarity of input is allowed and diode clamping A potted multiplie~,$afi be used to obtain the double (see Figure 27) protects against accidental latch-up, frequency tom@'~@nt, but frequency would be limited by its This circuit also may be adjusted in the closed-loop mode internal Iev@*arnplififer. In the monolithic units, the as follows: amplifier k $mi&d. 1. Set VZ to +.01 V and adjust P4 (output offset) for In a @#%~~oubler circuit, conventional + 15 V supplies VO = +0.316 V, being careful to approach the output aret,:~sed$$n input dynamic range of 5.0 V peak-to-peak is from the positive side to preclude the effect of the output alt~~d. The circuit generates wave-forms that are double diode clamping. fJ$r&$uency; less than 17. distortion is encountered without 2. Set VZ to 4.9 V and adjust P2 (X adjust) for ~t~%!$~fing. The configuration has been successfully used in .'~.:t,.>~t!. .,~:.{ Vo = +3.0 v. "$;,~;excess of 200 kHz; reducing the scale factor by decreasing 3. Set VZ to -10 V and adjust P3 (scale factor adjust} `" the load resistors can further expand the bandwidth. ~.. for VO = +10 V. Figure 29 represents an application for the monolithic 4. Steps 1 through 3 may be repeated as ne~$s~ to multiplier as a balanced modulator. Here, the audio input ,.,\\ .~.$f;f~,t$ .~.~k.$ achieve desired accuracy. signal is 1.6 kHz and the carrier is 40 kHz. I I MC1495 `"ist~:?; 10 k ,,,....,,J, t:.i's, 3 13 i~ 8 13k 12 ~-- LI P. Factor ~ ,J!. .-, -- To ~Offset (See H~ure13) MOTOROLA ANALOG !C DEVICE DATA I - 13k 5.0 k ~' P4 20 k RL output ofls~t L VO T tt- & Al AA. 12 k )k I MC1741C "z -lo<vz<tov Adjust 13 MC1495 The Figure 28. Frequency Doubler Ry 8.2 k defining K(EmCOS Vcc +15 v RX 8.2 k for balanced modulation is equation * [ COS Wmt) (EC COS @et)= (Oc+ Qm)t+ COS (Oc- Om) t ] 4 (< E COS mt 5.0 Vpp) 2 3.3 k Offset Y MC1495 ~ Adjust . 12 ~ 14 3 13 6,8 k 7 1,0 pF R1 3.3 k *cl' `Select E2 e.= To cos 2 wt where mc is the carrier frequency, ~m is the modulator frequency and K is the multiplier gain constant. AC coupling at the output eliminates the need for le~~a translation or an operational amplifier; a higher op$~a~~ ,,\. .:$+.. . -t frequency results. ~}? A problem common to communications is to. &R/&t~~he intelligence from single-sideband received si~,$b~ne ssb .1:$ .,*> s.,. *.<*. signal is of the form: essb = A cos (Oc + m~~$~r?" J `m and if multiplied by the appropriate c~,rfi&@~#veform, cos met, .,< u -15V essbecarfier =+ When two equal cosine waves are applied 10X and Y, the result is a wave shape of twice the input frequency, For ttis example the input was a 10 kHz signal, output wes 20 kHz, Figure 29'. Balanced Modulator (A) ey = E COS ex = E COS Omt [Cos (2~'*k)t + Cos (WC}t ]. ~ :. ;p.,:+\T\, .$$:: >~1. +\\*!t, If the frequency of the ~l~;l~~ited carrier signal (wc) is ascetiained in advance,'<~~~:@signer can insert a low pass filter and obtain the ,~W2)''&oswct) term with ease. He/she also can use an o~"&@"*al amplifier for a combination level shift-active filte~$~~~% external component. But in potted multipliers, ~de~.ij$~he frequency range can be covered, the operational'<~plifier is inside and not accessible, so the user must ~~ept t~e level shiting provided, and still add a low pas~%{~e~s ., ,..x~~de Modulation ""l~~~he multiplier performs amplitude modulation, similar to ,$, ~~lanced modulation, when a dc term is added to the * modulating signal with the Y-offset adjust potentiometer (see Figure 30). Ott Here, the identity is: Offset Y Adjust x Em(l + m cos ~mt) Ec cos ~ct = KEmEccos ~ct + KEmEcm 2 [ COS(Wc + Wm)t + COS (WC - Wm) t ] where m indicates the degrees of modulation. Since m is adjustable, via potentiometer P1, 1007. modulation is possible. Wthout extensive tweaking, 960/0 modulation may be obtained where @c and ~m are the same as in the balanced modulator example. Linear Gain Control To obtain linear gain control, the designer can feed to one of the two MC1495 inputs a signal that will vary the unit's gain. The following example demonstrates the feasibility of this application. Suppose a 200 kHz sinewave, 1,0 V peak-to-peak, is the signal to which a gain control will be added. The dynamic range of the control voltage VC is O V to +1.0 V. These must be ascertained and the proper values of R.x and Ry can be selected for optimum performance. For the 200 kHz operating frequency, load resistors of 100 Q were chosen to broaden'the operating bandwidth of the multiplier, but gain was sacrificed, It maybe made up with an amplifier operating at the appropriate frequency (see Figure 31). 14 MOTOROLA ANALOG IC DEVICE DATA MC1 495 figure 30. Amplitude Modulation Y.Modulation A~ust Rx 8.2k vcc=t15v 4 ey = EcosOmt ex = Ecosomt fly 8.2k I RL1 9 & .Y x MC1495 ! 12 14 OffsetAdjust 34 13+ 47 `Select J e. ex,ey <5.0VPP 6.8k rd I.OKFT The signal is applied to the unit's Y-input. Since the total input range is limited to 1.0 Vpp, a 2.0 V swing, a current source of 2.0 mA and an Ry value of 1.0 kQ is chosen. This takes best advantage of the dynamic range and insures linear operation in the Y-channel. Since the X-input varies between Oand +1.0 V, the current source selected was 1.0 mA, and the RX value chosen was 2.0 kQ. This also insures linear operation over the X-input dynamic ~ange. Choosing RL--= 100 assures wide bandwidth operation. .~,,,~~N2 in the numerator of the equation is missing in this scale "~~~hctor expression because the output is single-ended and ac ,{:t~~`" coupled. Linear Gain Control 1,25 y~= 1.OV 200k~z Y" 1,0 Y T 4 51 2 -= 0.75 Z= o > 0.5 100 100 i14 1 I 0.25 ! 1 1 1 I 1 1.2 VAGC(V) MOTOROLA ANALOG IC DEVICE DATA 15 MC1495 OUTLINE DIMENSIONS i ., "\.<w `+,.,.,. Motorola ~se~~~fie right to make changes without futiher notice to any products herein. Motorola makes no warranty, representation or guarantee regarding the sC~~@~~{#,@tsproducts for any pafiicular purpose, nor does Motorola aesume any liability arising out of the application or use of any product or circuit, and,~~~~?]]y disclaims any and all liability, including without limitation consequential or incidental damages. `Typica~ parameters can and do va~ in different ~~lld~ons. All operating parameters, including `Typicals" must be validated for aach customer application by customer's technical expefls. Motorola doss ~@*bY anY Iicenae under its Patent fights nor the fights of others. Motorola products are not dasigned, intended, or authorized for use as components in s~~ams intended for surgical implant into the body, or other applicafiona intended to suppofl or sustain life, or for any other application in which the failure of th&Motorola product could creata a situation where personal injury or death may occur. Should Buyer purchase or use Motorola products for any such unintended or unauthorized application, Buyar shall indemnify and hold Motorola and its officers, employees, subsidiatias, affiliates, and distributors harmless against all claims, costs, damages, and expanses, and reasonable attorney faes arising out of, diractly or indirectly, any claim of parsonal injury or death associated with such unintended or unauthorized usa, even if such claim alleges that Motorola was negligent regarding tha design or manufacture of the part. Motorola and @ are registered trademarks of Motorola, Inc. Motorola, Inc. is an Equal Opportunity/Afirmative Action Employer. How to reach us: USA/ EUROPE: Motorola Literature Mstfibution; PO. Box 20912; Phoenix, Arizona 85036, 14W1-2M7 MFAX: RMFAXO@email.sps. mot.com -TOUCHTONE INTERNET htfp://Design-NET.com @ M=OROLA o 1PHX3602H JAPAN Nippon Motorola Ltd.; TatsumWPWLDC, Toshikateu Otsuki, 6FSeibWufsuryWanter, >142Tabumi Kottiu, To~olW, Japan. OW21W15 (602) 2&609 PRl~EDIN HONG KONG: Motorola Semiconductors H.K. Ltd.; 8B Tai Ping industrial Park, 51 Ting Kok Road, Tai Po, N.T, Hong Kong. 652-26629298 USA 9/95 IMPERIALLITHO 14904 4.500 L,N/lNTYC~M MC14951D llllllllllllllllllllllllllllllllllllllllllllllllll