–5–

REV. B

AD532

DYNAMIC CHARACTERISTICS

The closed loop frequency response of the AD532 in the multi-

plier mode typically exhibits a 3 dB bandwidth of 1 MHz and

rolls off at 6 dB/octave thereafter. Response through all inputs is

essentially the same as shown in Figure 7. In the divide mode,

the closed loop frequency response is a function of the absolute

value of the denominator voltage as shown in Figure 8.

Stable operation is maintained with capacitive loads to 1000 pF

in all modes, except the square root for which 50 pF is a safe

upper limit. Higher capacitive loads can be driven if a 100

Ω

resistor is connected in series with the output for isolation.

Figure 8. Frequency Response, Dividing

POWER SUPPLY CONSIDERATIONS

Although the AD532 is tested and specified with

±15 V dc

supplies, it may be operated at any supply voltage from

±10 V

to

±18 V for the J and K versions, and ±10 V to ±22 V for the S

version. The input and output signals must be reduced propor-

tionately to prevent saturation; however, with supply voltages

below

±15 V, as shown in Figure 9. Since power supply sensitiv-

ity is not dependent on external null networks as in the AD530

and other conventionally nulled multipliers, the power supply

rejection ratios are improved from 3 to 40 times in the AD532.

Figure 9. Signal Swing vs. Supply

NOISE CHARACTERISTICS

All AD532s are screened on a sampling basis to assure that

output noise will have no appreciable effect on accuracy. Typi-

cal spot noise vs. frequency is shown in Figure 10.

Figure 10. Spot Noise vs. Frequency

APPLICATIONS CONSIDERATIONS

The performance and ease of use of the AD532 is achieved

through the laser trimming of thin-film resistors deposited di-

rectly on the monolithic chip. This trimming-on-the-chip tech-

nique provides a number of significant advantages in terms of

cost, reliability and flexibility over conventional in-package

trimming of off-the-chip resistors mounted or deposited on a

hybrid substrate.

First and foremost, trimming on the chip eliminates the need

for a hybrid substrate and the additional bonding wires that are

required between the resistors and the multiplier chip. By trim-

ming more appropriate resistors on the AD532 chip itself, the

second input terminals that were once committed to external

trimming networks (e.g., AD530) have been freed to allow fully

differential operation at both the X and Y inputs. Further, the

requirement for an input attenuator to adjust the gain at the Y

input has been eliminated, letting the user take full advantage of

the high input impedance properties of the input differential

amplifiers. Thus, the AD532 offers greater flexibility for both

algebraic computation and transducer instrumentation

applications.

Finally, provision for fine trimming the output voltage offset has

been included. This connection is optional, however, as the

AD532 has been factory-trimmed for total performance as

described in the listed specifications.

REPLACING OTHER IC MULTIPLIERS

Existing designs using IC multipliers that require external trim-

ming networks (such as the AD530) can be simplified using the

pin-for-pin replaceability of the AD532 by merely grounding

be grounded when unused.)