AD532

–4–

REV. B

AD532 PERFORMANCE CHARACTERISTICS

Multiplication accuracy is defined in terms of total error at

+25

°C with the rated power supply. The value specified is in

feedback and scale factor error. To this must be added such

application-dependent error terms as power supply rejection,

common-mode rejection and temperature coefficients (although

worst case error over temperature is specified for the AD532S).

Total expected error is the rms sum of the individual compo-

nents since they are uncorrelated.

Accuracy in the divide mode is only a little more complex. To

achieve division, the multiplier cell must be connected in the

feedback of the output op amp as shown in Figure 13. In this

configuration, the multiplier cell varies the closed loop gain of

the op amp in an inverse relationship to the denominator volt-

age. Thus, as the denominator is reduced, output offset, band-

width and other multiplier cell errors are adversely affected. The

divide error and drift are then

m

the absolute value of the denominator.

NONLINEARITY

Nonlinearity is easily measured in percent harmonic distortion.

The curves of Figures 3 and 4 characterize output distortion as

a function of input signal level and frequency respectively, with

one input held at plus or minus 10 V dc. In Figure 4 the sine

wave amplitude is 20 V (p-p).

Figure 3. Percent Distortion vs. Input Signal

Figure 4. Percent Distortion vs. Frequency

AC FEEDTHROUGH

AC feedthrough is a measure of the multiplier’s zero suppres-

sion. With one input at zero, the multiplier output should be

zero regardless of the signal applied to the other input. Feed-

through as a function of frequency for the AD532 is shown in

range. It consists primarily of the second harmonic and is mea-

sured in millivolts peak-to-peak.

Figure 5. Feedthrough vs. Frequency

COMMON-MODE REJECTION

The AD532 features differential X and Y inputs to enhance its

flexibility as a computational multiplier/divider. Common-mode

rejection for both inputs as a function of frequency is shown in

Figure 6. CMRR vs. Frequency

Figure 7. Frequency Response, Multiplying