FEATURES
Pretrimmed to ⴞ0.25% max 4-Quadrant Error (AD534L)
All Inputs (X, Y and Z) Differential, High Impedance for
[(X
Scale-Factor Adjustable to Provide up to X100 Gain
Low Noise Design: 90 V rms, 10 Hz–10 kHz
Low Cost, Monolithic Construction
Excellent Long Term Stability
APPLICATIONS
High Quality Analog Signal Processing
Differential Ratio and Percentage Computations
Algebraic and Trigonometric Function Synthesis
Wideband, High-Crest rms-to-dc Conversion
Accurate Voltage Controlled Oscillators and Filters
Available in Chip Form
PRODUCT DESCRIPTION
The AD534 is a monolithic laser trimmed four-quadrant multiplier divider having accuracy specifications previously found
only in expensive hybrid or modular products. A maximum
multiplication error of ±0.25% is guaranteed for the AD534L
without any external trimming. Excellent supply rejection, low
temperature coefficients and long term stability of the on-chip
thin film resistors and buried Zener reference preserve accuracy
even under adverse conditions of use. It is the first multiplier to
offer fully differential, high impedance operation on all inputs,
including the Z-input, a feature which greatly increases its flexibility and ease of use. The scale factor is pretrimmed to the
standard value of 10.00 V; by means of an external resistor, this
can be reduced to values as low as 3 V.
The wide spectrum of applications and the availability of several
grades commend this multiplier as the first choice for all new
designs. The AD534J (±1% max error), AD534K (±0.5% max)
and AD534L (±0.25% max) are specified for operation over the
0°C to +70°C temperature range. The AD534S (±1% max) and
AD534T (±0.5% max) are specified over the extended temperature range, –55°C to +125°C. All grades are available in her-
metically sealed TO-100 metal cans and TO-116 ceramic DIP
packages. AD534J, K, S and T chips are also available.
PROVIDES GAIN WITH LOW NOISE
The AD534 is the first general purpose multiplier capable of
providing gains up to X100, frequently eliminating the need for
separate instrumentation amplifiers to precondition the inputs.
The AD534 can be very effectively employed as a variable gain
differential input amplifier with high common-mode rejection.
The gain option is available in all modes, and will be found to
simplify the implementation of many function-fitting algorithms
) (Y1 – Y2)/10 V] + Z2 Transfer Function
1 – X2
Precision IC Multiplier
AD534
PIN CONFIGURATIONS
TO-100 (H-10A)
Package
LCC (E-20A)
Package
such as those used to generate sine and tangent. The utility of
this feature is enhanced by the inherent low noise of the AD534:
90 µV, rms (depending on the gain), a factor of 10 lower than
previous monolithic multipliers. Drift and feedthrough are also
substantially reduced over earlier designs.
UNPRECEDENTED FLEXIBILITY
The precise calibration and differential Z-input provide a degree
of flexibility found in no other currently available multiplier.
Standard MDSSR functions (multiplication, division, squaring,
square-rooting) are easily implemented while the restriction to
particular input/output polarities imposed by earlier designs has
been eliminated. Signals may be summed into the output, with
or without gain and with either a positive or negative sense.
Many new modes based on implicit-function synthesis have
been made possible, usually requiring only external passive
components. The output can be in the form of a current, if
desired, facilitating such operations as integration.
TO-116 (D-14)
Package
1
X1
2
X2
3
NC
NC
AD534
4
SF
TOP VIEW
(Not to Scale)
5
6
Y1
7
Y2
NC = NO CONNECT
14
+V
S
13
NC
12
OUT
11
Z1
10
Z2
9
NC
8
–V
S
REV. B
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
Total Error
T
Total Error vs. Temperature±0.022±0.015±0.008%/°C
Scale Factor Error
Temperature-Coefficient of
1
(–10 V ≤X, Y ≤ +10 V)ⴞ1.0ⴞ0.5ⴞ0.25%
= min to max±1.5±1.0±0.5%
A
(SF = 10.000 V Nominal)
2
– X2)( Y1– Y2)
( X
1
10 V
+ Z
– X2)( Y1– Y2)
( X
2
1
10 V
+ Z
2
– X2)( Y1– Y2)
( X
1
10 V
+ Z
2
±0.25±0.1±0.1%
Scaling Voltage±0.02±0.01±0.005%/°C
Supply Rejection (±15 V ± 1V)±0.01±0.01±0.01%
Nonlinearity, X (X = 20 V p-p, Y = 10 V)±0.4±0.2ⴞ0.3±0.10ⴞ0.12%
Nonlinearity, Y (Y = 20 V p-p, X = 10 V)±0.2± 0.1ⴞ0.1±0.005ⴞ0.1%
Feedthrough
X = 20 V p-p 50 Hz)±0.3±0.15ⴞ0.3±0.05ⴞ0.12%
Feedthrough
Y = 20 V p-p 50 Hz)±0.01±0.01ⴞ0.1±0.003ⴞ0.1%
Output Offset Voltage±5ⴞ30±2ⴞ15±2ⴞ10mV
Output Offset Voltage Drift200100100µV/°C
DYNAMICS
Small Signal BW (V
1% Amplitude Error (C
Slew Rate (V
Settling Time (to 1%, ∆V
3
, X (Y Nulled,
3
, Y (X Nulled,
= 0.1 rms)111MHz
OUT
= 1000 pF)505050kHz
LOAD
20 p-p)202020V/µs
OUT
= 20 V)222µs
OUT
NOISE
Noise Spectral-Density SF = 10 V0.80.80.8µV/√Hz
Wideband Noise f = 10 Hz to 5 MHz111mV/rms
Wideband Noise f = 10 Hz to 10 kHz909090µV/rms
SF = 3 V
4
0.40.40.4µV/√Hz
OUTPUT
Output Voltage Swingⴞ11ⴞ11ⴞ11V
Output Impedance (f ≤1 kHz)0.10.10.1Ω
Output Short Circuit Current
= 0, TA = min to max)303030mA
(R
L
Amplifier Open Loop Gain (f = 50 Hz)707070dB
INPUT AMPLIFIERS (X, Y and Z)
5
Signal Voltage Range (Diff. or CM±10±10± 10V
Operating Diff.)±12±12±12V
Offset Voltage X, Y±5ⴞ20±2ⴞ10±2ⴞ10mV
Offset Voltage Drift X, Y1005050µV/°C
Offset Voltage Z±5ⴞ30±2ⴞ15±2
Offset Voltage Drift Z200100100µV/°C
Figures given are percent of full scale, ±10 V (i.e., 0.01% = 1 mV).
2
May be reduced down to 3 V using external resistor between –VS and SF.
3
Irreducible component due to nonlinearity: excludes effect of offsets.
4
Using external resistor adjusted to give SF = 3 V.
5
See Functional Block Diagram for definition of sections.
Specifications subject to change without notic
e.
Specifications shown in boldface are tested on all production units at final electrical
test. Results from those tests are used to calculate outgoing quality levels. All min and
max specifications are guaranteed, although only those shown in boldface are tested
on all production units.
REV. B–2–
Page 3
AD534
ModelAD534SAD534T
MinTypMaxMinTypMaxUnits
MULTIPLIER PERFORMANCE
Transfer Function
Total Error
T
A
Total Error vs. Temperatureⴞ0.02ⴞ0.01%/°C
Scale Factor Error
Temperature-Coefficient of
1
(–10 V ≤ X, Y ≤ +10 V)ⴞ1.0ⴞ0.5%
= min to maxⴞ2.0±1.0%
(SF = 10.000 V Nominal)
2
– X2)( Y1– Y2)
( X
1
– X2)( Y1– Y2)
( X
10 V
+ Z
2
1
10 V
+ Z
2
±0.25±0.1%
Scaling Voltage±0.02ⴞ0.005%/°C
Supply Rejection (±15 V ± 1V)±0.01±0.01%
Nonlinearity, X (X = 20 V p-p, Y = 10 V)±0.4±0.2ⴞ0.3%
Nonlinearity, Y (Y = 20 V p-p, X = 10 V)±0.2±0.1ⴞ0.1%
Feedthrough
X = 20 V p-p 50 Hz)±0.3±0.15ⴞ0.3%
Feedthrough
Y = 20 V p-p 50 Hz)±0.01±0.01ⴞ0.1%
Output Offset Voltage±5
Output Offset Voltage Drift500300µV/°C
3
, X (Y Nulled,
3
, Y (X Nulled,
±
30±2ⴞ15mV
DYNAMICS
Small Signal BW (V
1% Amplitude Error (C
Slew Rate (V
Settling Time (to 1%, ∆V
OUT
= 0.1 rms)11MHz
OUT
= 1000 pF)5050kHz
LOAD
20 p-p)2020V/µs
= 20 V)22µs
OUT
NOISE
Noise Spectral-Density SF = 10 V0.80.8µV/√Hz
Wideband Noise f = 10 Hz to 5 MHz1.01.0mV/rms
Wideband Noise f = 10 Hz to 10 kHz9090µV/rms
SF = 3 V
4
0.40.4µV/√Hz
OUTPUT
Output Voltage Swing
±
11
±
11V
Output Impedance (f ≤ 1 kHz)0.10.1Ω
Output Short Circuit Current
= 0, TA = min to max)3030mA
(R
L
Amplifier Open Loop Gain (f = 50 Hz)7070dB
INPUT AMPLIFIERS (X, Y and Z)
5
Signal Voltage Range (Diff. or CM±10±10V
Operating Diff.)±12±12V
Offset Voltage X, Y±5ⴞ20±2ⴞ10mV
Offset Voltage Drift X, Y100150µV/°C
Offset Voltage Z±5ⴞ30±2ⴞ15mV
Offset Voltage Drift Z500300µV/°C
CMRR60807090dB
Bias Current0.82.00.82.0µA
Offset Current0.10.1µA
Differential Resistance1010MΩ
DIVIDER PERFORMANCE
Transfer Function (X1 > X2)
Total Error
1
(X = 10 V, –10 V ≤Z ≤+10 V)±0.75±0.35%
(X = 1 V, –1 V ≤ Z ≤ +1 V)±2.0±1.0%
(0.1 V ≤ X ≤ 10 V, –10 V ≤Z ≤ 10 V)±2.5±1.0 %
Figures given are percent of full scale, ±10 V (i.e., 0.01% = 1 mV).
2
May be reduced down to 3 V using external resistor between –VS and SF.
3
Irreducible component due to nonlinearity: excludes effect of offsets.
4
Using external resistor adjusted to give SF = 3 V.
5
See Functional Block Diagram for definition of sections.
S
pecifications shown in boldface are tested on all production units at final electrical
test. Results from those tests are used to calculate outgoing quality levels. All min and
max specifications are guaranteed, although only those shown in boldface are tested
on all production units.
Specifications subject to change without notice.
REV. B–3–
Page 4
AD534
470kV
50kV
1kV
TO APPROPRIATE
INPUT TERMINAL
+V
S
–V
S
WARNING!
ESD SENSITIVE DEVICE
CHIP DIMENSIONS AND BONDING DIAGRAM
Dimensions shown in inches and (mm).
Contact factory for latest dimensions.
+V
S
–V
S
The
X
1
X
2
SF
Y
1
Y
2
THE AD534 IS AVAILABLE IN LASER - TRIMMED CHIP FORM
rmal C
haracteristics
0.100 (2.54)
Thermal Resistance θJC = 25°C/W for H-10A
= 150°C/W for H-10A
θ
JA
= 25°C/W for D-14 or E-20A
θ
JC
= 95°C/W for D-14 or E-20A
θ
JA
OUT
Z
ABSOLUTE MAXIMUM RATINGS
Supply Voltage±18 V±22 V
Internal Power Dissipation500 mW*
Output Short-Circuit to GroundIndefinite*
Input Voltages, X1 X2 Y1 Y2 Z1 Z
Rated Operating Temperature Range0°C to +70°C–55°C to
0.076
(1.93)
Z
1
2
Storage Temperature Range–65°C to +150°C*
Lead Temperature Range, 60 s Soldering+300°C*
AD534JD0°C to +70°CSide Brazed DIPD-14
AD534KD0°C to +70°CSide Brazed DIPD-14
AD534LD0°C to +70°CSide Brazed DIPD-14
AD534JH0°C to +70°CHeaderH-10A
AD534JH/+0°C to +70°CHeaderH-10A
AD534KH0°C to +70°CHeaderH-10A
AD534KH/+0°C to +70°CHeaderH-10A
AD534LH0°C to +70°CHeaderH-10A
AD534K Chip0°C to +70°CChip
AD534SD–55°C to +125°CSide Brazed DIPD-14
AD534SD/883B–55°C to +125°CSide Brazed DIPD-14
AD534TD–55°C to +125°CSide Brazed DIPD-14
AD534TD/883B–55°C to +125°CSide Brazed DIPD-14
JM38510/13902BCA–55°C to +125°CSide Brazed DIPD-14
JM38510/13901BCA–55°C to +125°CSide Brazed DIPD-14
AD534SE–55°C to +125°CLCCE-20A
AD534SE/883B–55°C to +125°CLCCE-20A
AD534TE/883B–55°C to +125°CLCCE-20A
AD534SH–55°C to +125°CHeaderH-10A
AD534SH/883B–55°C to +125°CHeaderH-10A
AD534TH–55°C to +125°CHeaderH-10A
AD534TH/883B–55°C to +125°CHeaderH-10A
JM38510/13902BIA–55°C to +125°CHeaderH-10A
JM38510/13901BIA–55°C to +125°CHeaderH-10A
AD534S Chip–55°C to +125°CChip
AD534T Chip–55°C to +125°CChip
CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection.
Although the AD534 features proprietary ESD protection circuitry, permanent damage may
occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD
precautions are recommended to avoid performance degradation or loss of functionality.
–4–REV. B
Page 5
AD534
X
1
X
2
Y
1
Y
2
Z
1
Z
2
AD534
= + Z
2
(X1 – X2) (Y1 – Y2)
10V
OUTPUT , 612V PK
X INPUT
610V FS
612V PK
Y INPUT
610V FS
612V PK
+15V
OUT
–V
S
+V
S
–15V
OPTIONAL SUMMING
INPUT, Z, 610V PK
SF
FUNCTIONAL DESCRIPTION
Figure 2 is a functional block diagram of the AD534. Inputs are
converted to differential currents by three identical voltage-tocurrent converters, each trimmed for zero offset. The product
of the X and Y currents is generated by a multiplier cell using
Gilbert’s translinear technique. An on-chip “Buried Zener”
provides a highly stable reference, which is laser trimmed to
provide an overall scale factor of 10 V. The difference between
XY/SF and Z is then applied to the high gain output amplifier.
This permits various closed loop configurations and dramatically reduces nonlinearities due to the input amplifiers, a dominant source of distortion in earlier designs. The effectiveness of
the new scheme can be judged from the fact that under typical
conditions as a multiplier the nonlinearity on the Y input, with
X at full scale (±10 V), is ±0.005% of FS; even at its worst
point, which occurs when X = ±6.4 V, it is typically only
±0.05% of FS Nonlinearity for signals applied to the X input,
on the other hand, is determined almost entirely by the multiplier element and is parabolic in form. This error is a major
factor in determining the overall accuracy of the unit and hence
is closely related to the device grade.
SF
X
X
Y
Y
Z
Z
2
1
2
1
2
1
AD534
+
V-1
–
+
V-1
–
+
V-1
–
STABLE
REFERENCE
AND BIAS
TRANSLINEAR
MULTIPLIER
ELEMENT
0.75 ATTEN
TRANSFER FUNCTION
V
= A – (Z1 – Z2)
O
A
HIGH GAIN
OUTPUT
AMPLIFIER
+V
–V
– X2) (Y1 – Y2)
(X
1
SF
OUT
S
S
The user may adjust SF for values between 10.00 V and 3 V by
connecting an external resistor in series with a potentiometer
between SF and –V
. The approximate value of the total resis-
S
tance for a given value of SF is given by the relationship:
R
SF
=5.4K
SF
10 −SF
Due to device tolerances, allowance should be made to vary RSF;
by ±25% using the potentiometer. Considerable reduction in
bias currents, noise and drift can be achieved by decreasing SF.
This has the overall effect of increasing signal gain without the
customary increase in noise. Note that the peak input signal is
always limited to 1.25 SF (i.e., ±5 V for SF = 4 V) so the overall
transfer function will show a maximum gain of 1.25. The performance with small input signals, however, is improved by
using a lower SF since the dynamic range of the inputs is now
fully utilized. Bandwidth is unaffected by the use of this option.
Supply voltages of ±15 V are generally assumed. However,
satisfactory operation is possible down to ±8 V (see Figure 16).
Since all inputs maintain a constant peak input capability of
±1.25 SF some feedback attenuation will be necessary to
achieve output voltage swings in excess of ±12 V when using
higher supply voltages.
OPERATION AS A MULTIPLIER
Figure 3 shows the basic connection for multiplication. Note
that the circuit will meet all specifications without trimming.
Figure 2. Functional Block Diagram
The generalized transfer function for the AD534 is given by:
V
OUT
= A
− X
( X
)(Y
1
2
SF
1−Y2
)
−(Z1− Z
)
2
where A = open loop gain of output amplifier, typically
70 dB at dc
X, Y, Z = input voltages (full scale = ±SF, peak =
±1.25 SF)
SF = scale factor, pretrimmed to 10.00 V but adjustable
by the user down to 3 V.
In most cases the open loop gain can be regarded as infinite,
and SF will be 10 V. The operation performed by the AD534,
can then be described in terms of equation:
( X
− X
)(Y
1
2
REV. B–5–
) =10 V ( Z1− Z
1−Y2
)
2
Figure 3. Basic Multiplier Connection
In some cases the user may wish to reduce ac feedthrough to a
minimum (as in a suppressed carrier modulator) by applying an
external trim voltage (±30 mV range required) to the X or Y
input (see Figure 1). Figure 19 shows the typical ac feedthrough
with this adjustment mode. Note that the Y input is a factor of
10 lower than the X input and should be used in applications
where null suppression is critical.
The high impedance Z
terminal of the AD534 may be used to
2
sum an additional signal into the output. In this mode the output amplifier behaves as a voltage follower with a 1 MHz small
signal bandwidth and a 20 V/µs slew rate. This terminal should
always be referenced to the ground point of the driven system,
particularly if this is remote. Likewise, the differential inputs
should be referenced to their respective ground potentials to
realize the full accuracy of the AD534.
Page 6
AD534
X
1
X
2
Y
1
Y
2
Z
1
Z
2
AD534
1
RS
(X1 – X2) (Y1 – Y2)
I
OUT
=
10V
INTEGRATOR
CAPACITOR
(SEE TEXT)
X INPUT
610V FS
612V PK
Y INPUT
610V FS
612V PK
OUT
–V
S
+V
S
CURRENT-SENSING
RESISTOR, R
S
, 2kV MIN
SF
A much lower scaling voltage can be achieved without any reduction of input signal range using a feedback attenuator as
shown in Figure 4. In this example, the scale is such that V
= XY, so that the circuit can exhibit a maximum gain of 10.
This connection results in a reduction of bandwidth to about
80 kHz without the peaking capacitor C
= 200 pF. In addition,
F
the output offset voltage is increased by a factor of 10 making
external adjustments necessary in some applications. Adjust-
ment is made by connecting a 4.7 MΩ resistor between Z
the slider of a pot connected across the supplies to provide
±300 mV of trim range at the output.
OUT
and
1
Figure 5. Conversion of Output to Current
X INPUT
610V FS
612V PK
Y INPUT
610V FS
612V PK
X
1
X
2
AD534
SF
Y
1
Y
2
+V
OUT
–V
+15V
S
OUTPUT , 612V PK
= (X
– X2) (Y1 – Y2)
1
Z
1
Z
2
S
90kV
10kV
–15V
(SCALE = 1V)
OPTIONAL
PEAKING
CAPACITOR
C
= 200pF
F
Figure 4. Connections for Scale-Factor of Unity
Feedback attenuation also retains the capability for adding a
signal to the output. Signals may be applied to the high imped-
terminal where they are amplified by +10 or to the
ance Z
2
common ground connection where they are amplified by +1.
Input signals may also be applied to the lower end of the 10 kΩ
resistor, giving a gain of –9. Other values of feedback ratio, up
to X100, can be used to combine multiplication with gain.
Occasionally it may be desirable to convert the output to a current, into a load of unspecified impedance or dc level. For example, the function of multiplication is sometimes followed by
integration; if the output is in the form of a current, a simple
capacitor will provide the integration function. Figure 5 shows
how this can be achieved. This method can also be applied in
squaring, dividing and square rooting modes by appropriate
choice of terminals. This technique is used in the voltagecontrolled low-pass filter and the differential-input voltage-tofrequency converter shown in the Applications section.
OPERATION AS A SQUARER
Operation as a squarer is achieved in the same fashion as the
multiplier except that the X and Y inputs are used in parallel.
The differential inputs can be used to determine the output
polarity (positive for X
= Yl and X2 = Y2, negative if either one
1
of the inputs is reversed). Accuracy in the squaring mode is
typically a factor of 2 better than in the multiplying mode, the
largest errors occurring with small values of output for input
below 1 V.
If the application depends on accurate operation for inputs that
are always less than ±3 V, the use of a reduced value of SF is
recommended as described in the Functional Description section (previous page). Alternatively, a feedback attenuator may
be used to raise the output level. This is put to use in the difference-of-squares application to compensate for the factor of 2
loss involved in generating the sum term (see Figure 8).
The difference-of-squares function is also used as the basis for a
novel rms-to-dc converter shown in Figure 15. The averaging
filter is a true integrator, and the loop seeks to zero its input.
For this to occur, (V
is well below the averaging time-constant). Hence V
forced to equal the rms value of V
)2 – (V
IN
)2 = 0 (for signals whose period
OUT
. The absolute accuracy of
IN
OUT
is
this technique is very high; at medium frequencies, and for
signals near full scale, it is determined almost entirely by the
ratio of the resistors in the inverting amplifier. The multiplier
scaling voltage affects only open loop gain. The data shown is
typical of performance that can be achieved with an AD534K,
but even using an AD534J, this technique can readily provide
better than 1% accuracy over a wide frequency range, even for
crest-factors in excess of 10.
–6–REV. B
Page 7
AD534
X
1
X
2
Y
1
Y
2
Z
1
Z
2
AD534
OUTPUT, 612V PK
10V (Z2 – Z1) +X
2
=
Z INPUT
10V FS
12V PK
OPTIONAL
SUMMING
INPUT,
X, 610V PK
OUT
–V
S
+V
S
SF
+15V
–15V
REVERSE
THIS AND X
INPUTS FOR
NEGATIVE
OUTPUTS
R
L
(MUST BE
PROVIDED)
+
–
OPERATION AS A DIVIDER
The AD535, a pin-for-pin functional equivalent to the AD534,
has guaranteed performance in the divider and square-rooter
configurations and is recommended for such applications.
Figure 6 shows the connection required for division. Unlike
earlier products, the AD534 provides differential operation on
both numerator and denominator, allowing the ratio of two
floating variables to be generated. Further flexibility results from
access to a high impedance summing input to Y
. As with all
1
dividers based on the use of a multiplier in a feedback loop, the
bandwidth is proportional to the denominator magnitude, as
shown in Figure 23.
X INPUT
(DENOMINATOR)
+10V FS
+12V PK
OPTIONAL
SUMMING
INPUT
610V PK
+
X
1
X
2
–
SF
AD534
Y
1
Y
2
+V
OUT
–V
S
Z
1
Z
2
S
+15V
Z INPUT
(NUMERATOR)
610V FS, 612V PK
–15V
OUTPUT, 612V PK
=
10V (Z2 – Z1)
(X
– X2)
1
+ Y
1
Figure 6. Basic Divider Connection
Without additional trimming, the accuracy of the AD534K
and L is sufficient to maintain a 1% error over a 10 V to 1 V
denominator range. This range may be extended to 100:1 by
simply reducing the X offset with an externally generated trim
voltage (range required is ±3.5 mV max) applied to the unused
X input (see Figure 1). To trim, apply a ramp of +100 mV to
+V at 100 Hz to both X
and Z1 (if X2 is used for offset adjust-
1
ment, otherwise reverse the signal polarity) and adjust the trim
voltage to minimize the variation in the output.*
Since the output will be near +10 V, it should be ac-coupled for
this adjustment. The increase in noise level and reduction in
bandwidth preclude operation much beyond a ratio of 100 to 1.
As with the multiplier connection, overall gain can be introduced by inserting a simple attenuator between the output and
Y
terminal. This option, and the differential-ratio capability of
2
the AD534 are utilized in the percentage-computer application
shown in Figure 12. This configuration generates an output
proportional to the percentage deviation of one variable (A) with
respect to a reference variable (B), with a scale of one volt per
percent.
OPERATION AS A SQUARE ROOTER
The operation of the AD534 in the square root mode is shown
in Figure 7. The diode prevents a latching condition which
could occur if the input momentarily changes polarity. As
shown, the output is always positive; it may be changed to a
negative output by reversing the diode direction and interchanging the X inputs. Since the signal input is differential, all combinations of input and output polarities can be realized, but
operation is restricted to the one quadrant associated with each
combination of inputs.
Figure 7. Square-Rooter Connection
In contrast to earlier devices, which were intolerant of capacitive
loads in the square root modes, the AD534 is stable with all
loads up to at least 1000 pF. For critical applications, a small
adjustment to the Z input offset (see Figure 1) will improve
accuracy for inputs below 1 V.
*See the AD535 data sheet for more details.
REV. B–7–
Page 8
AD534–Applications Section
X
1
X
2
Y
1
Y
2
Z
1
Z
2
OUTPUT = 16 EC sin vt
10V
E
M
OUT
–V
S
+V
S
SF
+15V
–15V
THE SF PIN OR A Z-ATTENUATOR CAN BE USED TO PROVIDE OVERALL
SIGNAL AMPLIFICATION, OPERATION FROM A SINGLE SUPPLY POSSIBLE;
BIAS Y
2
TO VS/2.
CARRIER
INPUT
E
C
sin vt
MODULATION
INPUT, 6E
M
AD534
9kV
1kV
X
1
X
2
Y
1
Y
2
Z
2
Z
1
AD534
OUTPUT = (100V)
B
A – B
(1% PER VOLT)
OUT
–V
S
+V
S
SF
+15V
–15V
OTHER SCALES, FROM 10% PER VOLT TO 0.1% PER VOLT
CAN BE OBTAINED BY ALTERING THE FEEDBACK RATIO.
B INPUT
(+VE ONLY)
A INPUT
(6)
The versatility of the AD534 allows the creative designer to
implement a variety of circuits such as wattmeters, frequency
doublers and automatic gain controls to name but a few.
A – B
2
X
X
A
+V
+15V
OUT
S
OUTPUT =
1
2
30kV
SF
A + B
2
Y
Y
B
AD534
1
2
Z
1
Z
2
–V
S
10kV
–15V
Figure 8. Difference-of-Squares
+15V
+V
X
CONTROL INPUT,
E
, ZERO TO 65V
C
SET
GAIN
1kV2kV
–V
S
SIGNAL INPUT,
E
, 65V PK
S
NOTES:
1) GAIN IS X 10 PER-VOLT OF E
2) WIDEBAND (10Hz – 30kHz) OUTPUT NOISE IS 3mV RMS, TYP
CORRESPONDING TO A.F.S. S/N RATIO OF 70dB
3) NOISE REFERRED TO SIGNAL INPUT, WITH E
1
X
2
SF
Y
1
Y
2
4) BANDWITH IS DC TO 20kHz, –3dB, INDEPENDENT OF GAIN
AD534
S
OUT
Z
1
Z
2
–15V
–V
S
, ZERO TO X 50
C
39kV
1kV
= 65V, IS 60mV RMS, TYP
C
A2 – B
10V
OUTPUT, 612V PK
EC E
S
=
0.1V
0.005mF
2
Figure 11. Linear AM Modulator
Figure 9. Voltage-Controlled Amplifier
1
2
AD534
Y
1
Y
2
+V
OUT
–V
+15V
S
4.7kV
Z
1
4.3kV
Z
2
S
3kV
–15V
X
X
18kV
10kV
INPUT, E
u
0 TO +10V
USING CLOSE TOLERANCE RESISTORS AND AD534L, ACCURACY
OF FIT IS WITHIN 60.5% AT ALL POINTS. u IS IN RADIANS.
SF
Figure 10. Sine-Function Generator
OUTPUT = (10V) sin u
WHERE u =
p E
2 10V
Figure 12. Percentage Computer
+V
OUT
–V
+15V
S
OUTPUT, 65V/PK
y
Z
1
Z
2
–15V
S
= (10V)
1 + y
WHERE y =
Y
(10V)
X
1
X
u
2
AD534
SF
INPUT, Y 610V FS
Y
1
Y
2
Figure 13. Bridge-Linearization Function
–8–
Page 9
+15V
82kV
7
AD211
EC 1
40 CR
2kV
OUTPUT
615V APPROX.
ADJ 8kHz
+15V
ADJ
1kHz
500V 2.2kV
–15V
(= R)
39kV
0.01
(= C)
3-30p
2
3
PINS 5, 6, 8 TO +15V
PINS 1, 4 TO –15V
f =
= 1kHz PER VOLT
WITH VALUES SHOWN
X
X
+V
1
2
S
OUT
AD534
Z
SF
+
Y
CONTROL
INPUT, E
100mV TO 10V
C
CALIBRATION PROCEDURE:
WITH E
TRIMMER CAPACITOR TO SET f = 8.000kHz. LINEARITY WILL TYPICALLY BE
WITHIN 6 0.1% OF FS FOR ANY OTHER INPUT.
DUE TO DELAYS IN THE COMPARATOR, THIS TECHNIQUE IS NOT SUITABLE
FOR MAXIMUM FREQUENCIES ABOVE 10kHz. FOR FREQUENCIES ABOVE
10kHz THE AD537 VOLTAGE-TO-FREQUENCY CONVERTER IS RECOMMENDED.
A TRIANGLE-WAVE OF 65V PK APPEARS ACROSS THE 0.01mF CAPACITOR; IF
USED AS AN OUTPUT, A VOLTAGE-FOLLOWER SHOULD BE INTERPOSED.
1
–
Y
2
= 1.0V, ADJUST POT TO SET f = 1.000kHz. WITH EC = 8.0V ADJUST