MC1495D - Motorola / Freescale Semiconductor

Order this document by MC1495/D

MOTOROLA

Wideband Linear

Four=Quadrant Multiplier

The MC1495 is designed for use where the output is alinear 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.

●

MCI 495

Excellent Linearity:

27. max Error on XInput, 47. max Error on YInput Over Temperature@”

1YOmax Error on XInput, 2Y. max Error on YInput at +25°C ‘

.J*::,!:,

\’t~+$,

Adjustable Scale Factor, K.’, +:*}

,>.:\:*.

‘ ‘‘i’$i},

Excellent Temperature Stability ,is(i:+>,. ,‘

.*.,..

;$ .,:,.

Wide Input Voltage Range: t10 V;,.

.+\ *~;\m,,3r&\.+

.:~.

f>.,s,,,.$;,.

+15 VOperation ..,}+:,:,,!<,.,,.+,.,

~:\.,:,\

INGS (TA = + 25°C, unless othewise noted.)

Symbol Value Unit

AV 30 Vdc

1, V1-vg, V1-V,2, V,-V4,

~“’~l-va,V12-V7, vg-v7, V8-V7, V4-V7)

Differential Input Signal v12–vg f(6+113 Rx) Vdc

v4–v8 *(6+13 Ry)

IDSUFFIX

PLASTIC PACKAGE

CASE 751A

(s0-14)

PSUFFIX

PLASTIC PACKAGE

CASE 646

ORDERING INFORMATION

Maximum Bias Current 13 10 mA

113 10 Tested Opereting

Device Temperature Range Package

Operating Temperature Range TA ‘c

MC1495 0to +70 MC1495D so-1 4

TA =0° to +70°C

MC1495B – 40 tO +125 MC1495P Plastic DIP

Storage Temperature Range Tstg –65to +150 Oc MC1495BP TA =–40° to +125°C Plastic DIP

0Motorola,inc. 1995

MC1495

ELECTRICAL CHARACTERISTICS (+V =+32 V, -V =-15 V,TA = + 25°C, 13=113=1.0 mA, RX =Ry =15 kQ,RL =11kQ,unless

othe~ise noted.)

Characteristics Figure Symbol Min Typ Max Unit

-ineaflty (Output Error in percent of full scale) 50/0

TA =+25°C

-lo<vx<+lo (vy=*lov) ERX -tl .0 *1.0

-lo<vy<+lo (vx=*lov) ,. ERy -*2.0 *2.0

TA =TLOW

tOTHigh

-locvx<+lo (vy=flov) ERX -*1.5 t2.0

-Io<vy< +lo(vx=tlov) ERy -,+!$

*3.0 f4.0 ..:<!+

:s:~+:>:.,.,

SquareMode Error (Accuracyin percent of full scale after 5ESQ ,y’;;&>a:

Offsetand scale Factoradjustment) .:., js

TA = + 25°C ‘~::j~#,,,~.>,~,,.

~~:~$

*0.75 S>,‘~’

——,,??.:\.‘~

:f;,,,

TA =TLOWtOTHigh *1,0 ;?;..,:i$$

“+$

—,~r ~:.-~..,:!

ScaleFactor (Adjustable)

(2RL )

—K0.1 ,:~~,,.:* ‘.

—

K= ..*,*,‘~$~.>$:s’

13 RxRy .,...’,.>*+>\,,*

,:’.:..,, S$

..,~:.k,~}

~, \,~

InputResistance(f= 20 Hz) 7‘.,., .

RinX -3@*k\;~., –Mfi

Riny –~’*&$ ““ -

DifferentialOutput Resistance(f= 20 Hz) 8RO –,;;>$~p -kQ

Input Bias Current *’rj*i,i,.,<.,,

6\%.,:s+,!,‘~

‘\ .PA

,bx =(lg +112) (14+18) TA = + 25°C Ibx, Iby ,~

~,~~ 2.0 8.0

..3:...

—l~y=y

2’ TA =TLOWtOTHigh .*$,.gcvq,.

.,,. 2.0 12

{.,!~,)),,

,.~j..‘::J$,~.,,.

Input OffsetCurrent ,,

.,,?>

6.,,:”,,*, ....

~..,,

,~,:.,+:~

;$$.”

llg-1121 pA

TA =+25°C Il\Qxll?$;l -

114-181 0.4 1.0

TA=TLOWtOTHigh ,13:;!,, —

,.,., 0.4 2.0

AverageTemperatureCoefficient of Input Offset Current 6~f*:‘+$%I?*[iOl

TA =TLOWto THigh nNOC

?: —

.~.~‘*y<,,

\:j.. 2.5 —

Output OffsetCurrent TA =+25°C e~’~~ ‘“’ 11001 10 50

1114-121 PA

TA =TLOWto THigh > “?* —20 100

AverageTemperatureCoefficient of Output Offset Current ~i/ .:,..,6lTCIOOl

TA =TLOWtOTHigh .).‘\\&*,\ nN”C

,, 20

,.,:,

~!.+ .?,.

Frequency Response \N~>~\+l,,;‘*/.,

!..

,.},$3

........*.::1~ 9,10

3.0 dB Bandwidth, RL =11kQ ,,}..”

t., ,.< “..,.~BW(3dB) -3.0 MHz

.s:>,,...,

3.0 dB Bandwidth, RL =50 Q(Transconductan@,@~@ dth) —

TBW(3dB) -80

3° Relative Phase Shift Between VX and VyWJ:Y@,.+ —

.,.,\“~:.+?;\J.,,‘‘~ MHz

fq –750 kHz

1YeAbsolute Error Dueto Input-Output Ph~~i~~~ —

fe —30 —kHz

Common Mode Input Swing sty~,?

.s$,.’**~\*.11

.~:~ ,,$ CMV

(Either Input) Vdc

t:,~,

.,,. ~t), ;? *10.5 *12 —

Common Mode Gain ~~:’ ~’:+~.

.+. TA = + 25°C 11

(Either Input) ~a,~~$$~~ TA=TLOWto THigh ACM – 50 -60 —dB

– 40 -50 —

Common Mode Quiescent i’r$~$f$ 12

.(.\” Vol -21

Output Voltage —Vdc

~,;;.

Y;si~$ ~V02 -21 —

DifferentialOutput,~o$~&~wing Capability 9Vo –

,,., +14 —vpk

power SUPPIY*~%ti& 12 s+ _5.0

.Jj:>ji. .::, —mVN

,,,,, .<>,\ s- -10 —

PowerS*pl~&urrent 12 17 6.0 7.0 mA

,,‘b,.,.t..

DC@m;Dssipation 12 pD -135 170 mW

,J>.k,,,,\ ....

~wt. THigh=+70°CfOr MC1495 TLOW=O°C

for MC1495

‘$; =+1 25°C for MCI 495B =- 40°C for MC1495B

2MOTOROLA ANALOG IC DEVICE DATA

●

MC1495

Figure 1. Multiplier Transfer Characteristic Figure 2. Transconductance Bandwidth

-8.0

–i

YInput

Output (KXY)

XInput

... >-...- <‘#l* 10k

Onset Ii4

—

5.0kAdjust

Scale —v.

Factor A1

Adjust y_ _$0.tpF -

●

-15 v

—NOTE: Adjust “Scale Factor AdjuaV for anull in VE.ThiS schematic for

illustrative purposes only, not specified for test condtions.

MOTOROLA ANALOG [C DEVICE DATA 3

MC1 495

Figure 5. Linearity (Using X-Y Plotter Technique)

Ry=15k Rx=15k t32v

** T

Figure 9. Bandwidth (RL = 11 kQ)

Ry=15k Rx=15k t32v

●

ein= 1.0V~S 1 9.1k

q“ 2 llk

—

Scale

Factor

4MOTOROLA ANALOG IC DEVICE DATA

MCI 495

Figure 10. Bandwidth (RL =50 Q)

oRy=510 Rx=510 t15v

q“ =1.0 Vms l.Ok )

,250 )

MC1495 ;50

—13

——3( 7R13 I

—0,1 pF

K=40 12k 13,7k

1T= eO

Scale

Factor 5,0 ka~o”’~F *CL< 3.0 pF

6.2 V

Figure 12. Power Supply Sensitivity

+32V +32 V(V+)

-—

●15k 15k e

49.1 kI

—9

4e 211k

2.0 k

Figure 11. Common Mode Gain and

Common Mode Input Swing

‘%

~0.1 pF m

Figure 14. Offset Adjust Circuit (Alternate)

!Vt

R5.1 v

To Rn 8Pot #1 Pot#2 To Pin 12

YOffset 10k 10k

Adjust ~xoffset

A~ust

ITII

-15V

2,0 k

v’”

Pot #2 To Pin 12

~XOffset

A~ust

() AA. tt

2.0 k—

10 k

-15 v

MOTOROLA ANALOG IC DEVICE DATA 5

MC1 495

Figure 15. Linearity versus Temperature

2.0

-1.6

z\ \

~1.4

y1,2

WC 0.8 \E

%0.6

w0.4

0.2

0-55 -25 0 25 50 75 100 125

TA, AMBIENT TEMPERATURE PC)

Figure 17. Error Contributed by Input

Differential Amplifier

Figure 16. Scale Factor versus Temperature

0.110

~0.105

~KAdjusted to 0.10Oat 25°C

+0,100

x- 0.095

-55 -25 0

-4.0 6.0 8.0 10 12 14

Rx or Ry (k Q)

IVII or IV71(V)

6MOTOROLA ANALOG IC DEVICE DATA

MC1495

OPERATION AND APPLICATIONS INFORMATION

Theory of Operation

The MCI 495 is amonolithic, four-quadrant multiplier

which operates on the principle of variable

transconductance. Adetailed 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 Xand Yinput voltages at

the multiplier input terminals.

DESIGN CONSIDERATIONS

General

The MC1 495 permits the designer to tailor the multiplier to

aspecific application by proper selection of external

components. External components may be selected to

optimize agiven 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

3dB 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 awideband operational amplifier should be used.

Stray output capacitance will depend to alarge extent on

circuit layout. ,*!.

‘*{,1,

>.,:;,,<*,>,.\~q.\\

Phase shift in the multiplier circuit result~~f,m” Iwo

sources: phase shift common to both Xand 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 Xand Y

channels). If the input to output p~~w~ is only 0.6°, the

output product of two sine wavqs %,,$hibit avector error of

1YO.A3° 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

‘~~~-’’’”” Vy(max) <13 Ry

..w~$$,,::,>

ExceedJ8~~i$jaiue will drive one side of the input amplifier

to “cuti&’hnd cause nonlinear operation.

,,$&urre* 13 and II 3are chosen at aconvenient 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 astraight 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.

Iil: ‘:.”$.

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~ -

~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 Xand Ysimilar 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 Xand Yinput 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 afunction 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).

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 )(Ry +~) IS

2kT

2kT and Ry >> —

with the assumption RX >> —

ql13 q13 “

At TA=+25°C and 113= 13= 1.0 mA,

3T=*T=52Q.

ql13 q13

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 toVI and V7. Exceeding these limits

will cause saturation or “cutoti of the input transistors. See

Step 4of 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 1for

negative swing. The potential at Pin 1determines the

quiescent level for transistors Q5, Q6, Q7 and Q8. This

potential should be related so that negative swing at Pins 2or

14 does not saturate those transistors. See General Design

Procedure for further information regarding selection of

these potentials,

MoToRoti ANALOG ICDEVICE DATA 7

MC1495

Figure 20. Basic Multiplier

~v+

Rx Ry ‘RL

{: :“

“x ttQ

12 14 .‘,, ,

=:1 Vo

l:i -

‘4, .- MC1495 -

“y

313 7 VO=KVx Vy

‘~

2RL

13 K=—Rx Ry 13

R3 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 3for further details.

GENERAL DESIGN PROCEDURE

Selection of component values is best demonstrated by

the following example. Assume resistive dividers are used at

the Xand Y-inputs to limit the maximum multiplier input to ~

5.0 V[VX =VY(ma~)] for a*10 Vinput [V~”= V~(max)] ●

(see Figure 21). If an overall scale factor of 1/1Ois desired,

Vy Vy (2VX) (2VY)= 4/1oVx VY

then, VO= ~= ,0 ,:!$,

sg:.;y.;:<ti,

,(,. ~,. ~ ,:, .. ~

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~

‘“v+T-’5V

—

-“x“y

8., MOTOROLA ANALOG IC DEVICE DATA

MC1495

To set currents 13 and 113 to the desired value, it is only

necessa~ to connect aresistor 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-’ ~7 v

14.3V or R13= 13.8 kQ

Let V–=–15V, then R13+500=— 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 afinal trim of the scale factor.

For this reason, as shown in Figure 21, resistor R3 is shown

as afixed resistor in series with apotentiometer.

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 3to ground can be used. In this case, the

single resistor would have avalue 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, !Y <13

Rx Ry

voltage. It should also be noticed that the collector voltage of

transistors Q3 and Q4 is at apotential which is two

diode-drops below the voltage at Pin 1. Thus, the voltage at

Pin 1should be about 2.0 Vhigher than the maximum input

voltage. Therefore, to handle +5.0 Vat the inputs, the voltage

at Pin 1must be at least +7.0 V. Let V1 =9.0 Vdc.

Since the current flowing into Pin 1is always equal to 213,

the voltage at Pin 1can be set by placing aresistor (RI) from

Pin 1to the positive supply: *,\

*’X,l,

$J,$<,.,,.,’~,’$:.

‘!,.~1+ts.,

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 asingle-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~Kiscircuit is given by:

..... t<<..

Agood 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

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 Vor VX =5.0 V,

Vy =5.0 V), their respective collector voltage should be at

least afew tenths of avolt higher than the maximum input

VO =(I2 –114) RL

21X Iy 2vxvy

And since IA–16 =12–114 =— —

13 =13RxRy

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

RO RO

12< V2 t

+V14 Vo

1144 *–

RL RL

,“”

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 ahigh common

mode rejection ratio. The MC1 456, and MC1 741 C

operational amplifiers meet these requirements.

MOTOROLA ANALOG IC DEVICE DATA 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 RO

And for this example, fiQ+ 1.0 mA= 15 V-11 v

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 Ylinearity,

and RX decreased somewhat so as not to materially affect

the Xlinearity, This avoids increasing RL significantly in order

to maintain aKof 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 base-

emitter 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 AVx(off)] [Vy +~o~{~@~j *VOO (1)

Where: K=scale factor,, ~;,. “~w”

Vx =“x” input,~~&:

Vy =“y” inptif~o*e

~ox =“x” i~~~et voltage

~oy =‘(y’~w offset voltage

VX(OH) .,p$y” ‘iihut offset adjust voltage

‘t(~~$$~:~utput offset voltage.

‘$w:$$y*input offset adjust voltage

,. ‘

}.>

~$., ,~,,i..

.’,*’ >i,,i,,.,w

,,,+~,,,

Figure 23. Multiplier with lmpro~pd ~~earity

-15V

●

~2”0k~20k

— —

-VxVy

10 MOTOROLA ANALOG IC DEVICE DATA

MC1495

X, Yand Output Offset Voltages

Xoxffyox:y

For most dc applications, all three offset adjust

potentiometers (PI, P2, P4) will be necessary. One or more

offset adjust potentiometers can be eliminated for ac

applications (see Figures 28,29, 30, 31).

If well regulated supply voltages are available, the offset

adjust circuit of Figure 13 is recommended. Otherwise, the

circuit of Figure 14 will greatly reduce the sensitivity to power

supply changes.

Scale Factor

The scale factor Kis set by P3 (Figure 21). P3 varies 13

which inversely controls the scale factor K. It should be noted

that current 13is one-half the current through RI. R1 sets the

bias level for Q5, Q6, Q7, and Q8 (see Figure 3). Therefore, to

be sure that these devices remain active under all conditions

of input and output swing, care should be exercised in

adjusting P3 over wide voltage ranges (see General Design

Procedure).

Adjustment Procedures

DC APPLICATIONS

Multiply

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

-,/,,$::,+:!?\*

designed for 10 V(max). ..,:>:. ,$$:,,.

$*. ,.,’’’t’t,$.:

.,,

Squaring Circuit ,>.,*. .

..,<,.‘.*~~>,,:<x~~:’.~

.,,. “+$?.

If the two inputs are tied together, the rp~&@~function is

squaring; that is VO =KV2 where Kis @~JscM# factor. Note

that all error terms can be eli~-~~$>~ith only three

adjustment potentiometers, thus, ell~{n,~ng one of the input

offset adjustments. Procedurq~~~{ nti%ing with adjustments

are given as follows: ~~,...:5,,

,,+,~:-+,

‘<i

~,.’.,;~,.:>,

,... ..1..,.

A. AC Procedure: t$t,.,$~s)’

+.$k:,,,.;>’$

1. Connect os@,@,*?~WOkHz, 15 Vpp) to input.

2. Monitor g~tpu$qt ~.O kHz with tuned voltmeter

and ad~~$~~ for desired gain. (Be sure to peak

resw.~f the voltmeter.)

3. ~#~}v,@meter to 1.0 kHz and adjust P1 for a

*ititim output voltage.

.,,?~ ~und input and adjust P4 (output offset) for

“’, OVdc output.

,,*.,.,,

$’ “’t$. ReDeat steps 1through 4as necessay.

The following adjustment procedure should be used to null “. w~ ‘

.,{~,+

+t.~!i@. DC Procedure:

the offsets and set the scale factor for the multiply mode of k; A

operation, (see Figure 21). +.,., 1. Set Vx =Vy =OVand adjust P4 (output offset

\xt+*}

..,,> \~otentiometer) such that Vo =OVdc

1. X-Input Offset .%\:

:i\.$.2. Set VX =Vy =1.0 Vand adjust P1 (Y-input offset

(a) Connect oscillator (1.0 kHz, 5.0 Vpp sin~{$~~’ potentiometer) such that the output voltage is

to the Y-input (Pin 4). ‘~~,+~.j

,,4. .,,,, +0.loov.

(b) Connect X-input (Pin 9) to ground. t&NJ~@t 3. Set VX =Vy =10 Vdc and adjust P3 such that

null at the output. .,,.’N’.?,:’~

.,:~.,,

“::,+by “4. Set Vx =Vy =–1 OVdc. Repeat steps 1through

2. Y-Input Offset ,,.., ].s 3as necessary.

(a) Connect oscillator (1.0 kHr$’Wpp sinewave)

to the X-input (Pin 9):<:,,*~,$~!.w;

(b) Connect Y-input (Pin~J t$ground.

at the outputi.. ‘3il\f#

3. Output Offset ~~.g~,l$ “

(a) ConneCj @t~~and Y-inputs to ground.

(b) Adjup8~M$t offset potentiometer (P4) until

th~ ~&@& voltage (VO) is OVdc.

4. Scqp::%;{ti

(a)$,A ,ly +1OVdc to both the Xand Y-inputs.

t~~~%~~?ust P3 to achieve +10 Vat the output.

~$:m;$$peat steps 1through 4as 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 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, .,

KVXVy -Vz

RI =R2 (1)

Solving for Vy, –R1 VZ

vy=— —

R2 K VX

-Vz

If RI=R2, Vy =—

KVX

–Vz

If Rl= KR2, Vy=— v~

(2)

(3)

(4)

Hence, the output voltage is the ratio of VZ to VX and

provides adivide function. This analysis is, of course, the

idealcondition, If the multiplier error is taken into account, the

output voltage is found to be:

(5)

where AE is the error voltage at the output of the multiplier.

Frornthis equation, it is seen that divide accuracy is strongly

dependent upon the accuracy at which the multiplier can be

set,: particularly at small values of Vy. For example, assume

that RI =R2, and K=1/1O.For these conditions the outpq~,bf

In terms of percentage error,

percentage error =*I x100%

or from Equation (5),

‘KVx [1

R2 AE

PED =

[1R1 VZ ‘. RI.I VZ (7)

.R2 K. VX *,\

*’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

error decreases). ,,~+,

,,? .~,s(,*

‘“~!.,1,~.,~‘

Acircuit that performs the divide func{~~r~.,~hown in

Figure 25. ~!,.>:y’,J.~

~.’yttti,,’

,,,<,:N.Nt*J*,

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 2of the multipliq$~$dl “&ways be in adirection

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:,,

Asuadted atiiustment procedure for the divide circuit.

l,~~e~.~z =OVand adjust the output offset potentiometer

$(~4) until the output voltage (Vo) remains at some (not

,,8,&~~~:decessarily zero) constant value as V~ is varied

“:~~~ between +1.0 Vand +1OV.

.2. Keep VZ at OV, set VX’ at +1OVand adjust the Yinput

$t”

the divide circuit is given by: offset potentiometer (Pl )until VO =OV.

,\(.*~>:~.,,

~~->..:.,>

‘{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 +1OV.

Keep V~ =VZ and adjust the scale factor potentiometer

(P3) until the average value of VO is-10 Vas VZ =Vx~ is

varied between +1.0 Vand +1OV.

error woltage of the divide circuit,~~.Q# expected to be a 5. Repeat steps 1through 4as necessay to achieve

hundred times the error of theb$i,c;~ultiplier circuit. optimum petiormance.

<$!~‘).Y<>$I,‘~.’,.!.~~

\!:;,>,,$s:

,’j.

●t15v

Rx Ry ,0.1WF

10k 10k ~ ~ ‘“ ~F

(~?

t3+

MC1495 MC1741C ●VO

+?2-lo Vz

tvo=~

12 MOTOROLA ANALOG IC DEVICE DATA

MC1495

Hgure 26. Basic Square Root Circuit AC APPLICATIONS

‘Z%zvo

L—or _

{Ivzl

“0= y

Square Root

Aspecial 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

that only one polarity of input is allowed and diode clamping

(see Figure 27) protects against accidental latch-up,

This circuit also may be adjusted in the closed-loop mode

as follows:

●4.

The applications that follow demonstrate the versatility of

the monolithic multiplier. If apotted 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 adiode where

the fundamental plus aseries 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

requires amplification. ?$7..

.~,};.,

,~”.,m.~~,

When amultiplier is used to double f~~qtiti the second

harmonic is obtained directly, exceptq~~~~~pqerm, which can

be removed with ac coupling. :?$;),~~. “

e. =KE2 COS2Q~‘$~ ‘$’

~?:t,i:.J~.

,+.f>$v~ji,~“

Apotted multiplie~,$afi be used to obtain the double

frequency tom@’~@nt, but frequency would be limited by its

internal Iev@*arnplififer. In the monolithic units, the

amplifier k$mi&d.

Set VZ to +.01 Vand adjust P4 (output offset) for In a@#%~~oubler circuit, conventional +15 Vsupplies

VO =+0.316 V, being careful to approach the output aret,:~sed$$n input dynamic range of 5.0 Vpeak-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

Set VZ to 4.9 Vand adjust P2 (X adjust) for ~t~%!$~fing. The configurationhas been successfully used in

Vo =+3.0 v. .’~.:t,.>~t!..,~:.{

“$;,~;excess of 200 kHz; reducing the scale factor by decreasing

Set VZ to -10 Vand 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

Steps 1through 3may be repeated as ne~$s~ to multiplier as abalanced modulator. Here, the audio input

achieve desired accuracy. ,.,\\

.~.$f;f~,t$.~.~k.$ signal is 1.6 kHz and the carrier is 40 kHz.

MC1495 I I I I MC1741C L

T●VO tt-

..t:.i’s,

‘“ist~:?;10 k3

LI ~~’

13 8~

12 -Al &

,,,..,,J, AA.

~13k —13k ●“z

12 k20 k

)k RL

P. To Offset 5.0 koutput

P4 ofls~t

Factor ~-lo<vz<tov

,J!..-,— (See H~ure13) Adjust

MOTOROLA ANALOG !C DEVICE DATA 13

MC1495

Figure 28. Frequency Doubler

Ry RX Vcc +15v

8.2k8.2 k

ECOS mt

(< 5.0Vpp) 23.3k

Offset Y~MC1495 R1

Adjust .12 14 3.3k

~3 13 7 *cl’

‘m

‘Select E2

6,8k1,0pF e.= To cos2wt

u-15V

Whentwoequalcosine waves are applied 10X and Y, the result

is awave 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 =

ex =

ECOS Omt

ECOS Ott

The defining equation for balanced modulation is

K(EmCOS Wmt) (EC COS @et)=

*[COS (Oc+Qm)t+ COS (Oc-Om)t ]

where mc is the carrier frequency, ~m is the modulator

frequency and Kis the multiplier gain constant.

AC coupling at the output eliminates the need for le~~a

translation or an operational amplifier; ahigher op$~a~~

frequency results. ,,\. .:$+...-t

~}?

Aproblem common to communications is to. &R/&t~~he

intelligence from single-sideband received si~,$b~ne ssb

signal is of the form: .,*>s. .1:$

,. *.<*.

essb =Acos (Oc +m~~$~r?”

and if multiplied by the appropriate c~,rfi&@~#veform, cos met,

.,<

essbecarfier =+[Cos (2~’*k)t +Cos (WC}t ].

~:.;p.,:+\T\,

+\\*!t,

.$$::>~1.

If the frequency of the ~l~;l~~ited carrier signal (wc) is

ascetiained in advance,’<~~~:@signer can insert alow pass

filter and obtain the ,~W2)’’&oswct) term with ease. He/she

also can use an o~”&@”*al amplifier for acombination 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 adc term is added to the

*modulating signal with the Y-offset adjust potentiometer (see

Figure 30). ●

Here, the identity is:

Em(l +mcos ~mt) Ec cos ~ct = KEmEccos ~ct +

KEmEcm

2[COS(Wc + Wm)t + COS (WC - Wm) t]

where mindicates the degrees of modulation. Since mis

adjustable, via potentiometer P1, 1007. modulation is

possible. Wthout extensive tweaking, 960/0modulation may

be obtained where @c and ~m are the same as in the

balanced modulator example.

Offset Y

Adjust x

Linear Gain Control

To obtain linear gain control, the designer can feed to one

of the two MC1495 inputs asignal 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 again control will be

added. The dynamic range of the control voltage VC is OVto

+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 Qwere

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

ey =EcosOmt

ex=Ecosomt

Y.ModulationA~ust

OffsetAdjust

fly Rx vcc=t15v

8.2k8.2k

●I

9RL1

●&

.Y !MC1495

x12 14

34 13+ 47

ex,ey<5.0VPP

‘Select J

6.8k I.OKFT

The signal is applied to the unit’s Y-input. Since the total

input range is limited to 1.0 Vpp, a2.0 Vswing, acurrent

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. -

Y“ Y

2100

100

.~,,,~~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

1,0

-= 0.75

>0.5

0.25

y~= 1.OV

200k~z

!111I1

VAGC(V) 1.2

MOTOROLA ANALOG IC DEVICE DATA 15

MC1495

OUTLINE DIMENSIONS

“\.<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 asituation 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 JAPAN Nippon Motorola Ltd.; TatsumWPWLDC, Toshikateu Otsuki,

6FSeibWufsuryWanter, >142Tabumi Kottiu, To~olW, Japan. OW21W15

MFAX: RMFAXO@email.sps. mot.com –TOUCHTONE (602) 2&609 HONG KONG: Motorola Semiconductors H.K. Ltd.; 8B Tai Ping industrial Park,

INTERNET htfp://Design-NET.com 51 Ting Kok Road, Tai Po, N.T, Hong Kong. 652-26629298

@M=OROLA o1PHX3602H PRl~EDIN USA 9/95 IMPERIALLITHO 14904 4.500 L,N/lNTYC~M MC14951D

llllllllllllllllllllllllllllllllllllllllllllllllll