®

MPY100

8

where K is a scale factor. In the MPY100, K is chosen to be

0.1.

Therefore, the output of the MPY100 is:

where A is the open-loop gain of the output amplifier.

Writing this last equation in terms of the separate inputs to

the MPY100 gives

the transfer function of the MPY100.

WIRING PRECAUTIONS

In order to prevent frequency instability due to lead induc-

tance of the power supply lines, each power supply should

be bypassed. This should be done by connecting a 10

µF

tantalum capacitor in parallel with a 1000pF ceramic capaci-

power supply common. The connection of these capacitors

should be as close to the MPY100 as practical.

(X

10

FIGURE 4. MPY100 Simplified Circuit Diagram.

Q

8

Q

7

+

R

X

2

21

1

R

X

2

V

X

–

X

2

–V

CC

Q

6

Q

5

+

R

Y

2

21

1

R

Y

2

V

Y

–

Q

10

Q

9

+

R

Z

2

21

1

R

Z

2

V

Z

–

Y

2

Z

2

R

CM

Q

2

Q

1

I

2

I

1

Q

4

Q

3

I

4

I

3

A

D

1

D

2

+V

CC

R

L

R

L

+

V

1

–

+

V

A

–

Y

1

X

1

Z

1

V

O

Out

CAPACITIVE LOADS

Stable operation is maintained with capacitive loads to

1000pF in all modes, except the square root mode for which

50pF is a safe upper limit. Higher capacitive loads can be

driven if a 100

Ω resistor is connected in series with the

MPY100’s output.

DEFINITIONS

TOTAL ERROR (Accuracy)

Total error is the actual departure of the multiplier output

voltage form the ideal product of its input voltages. It

includes the sum of the effects of input and output DC

offsets, gain error and nonlinearity.

OUTPUT OFFSET

SCALE FACTOR ERROR

Scale factor error is the difference between the actual scale

factor and the ideal scale factor.

NONLINEARITY

Nonlinearity is the maximum deviation from a best

straightline (curve fitting on input-output graph) expressed

as a percent of peak-to-peak full scale output.

FEEDTHROUGH