a
FEATURES
DC to >500 MHz Operation
Differential 1 V Full-Scale Inputs
Differential 4 mA Full-Scale Output Current
Low Distortion (
≤
0.05% for 0 dBm Input)
Supply Voltages from 4 V to 9 V
Low Power (280 mW typical at V
S
= 5 V)
APPLICATIONS
High Speed Real Time Computation
Wideband Modulation and Gain Control
Signal Correlation and RF Power Measurement
Voltage Controlled Filters and Oscillators
Linear Keyers for High Resolution Television
Wideband True RMS
500 MHz Four-Quadrant Multiplier
AD834
FUNCTIONAL BLOCK DIAGRAM
(W)
PRODUCT DESCRIPTION
The AD834 is a monolithic laser-trimmed four-quadrant analog
multiplier intended for use in high frequency applications, hav-
ing a transconductance bandwidth (R
L
= 50
Ω)
in excess of
500 MHz from either of the differential voltage inputs. In multi-
plier modes, the typical total full-scale error is 0.5%, dependent
on the application mode and the external circuitry. Performance
is relatively insensitive to temperature and supply variations, due
to the use of stable biasing based on a bandgap reference genera-
tor and other design features.
To preserve the full bandwidth potential of the high speed
bipolar process used to fabricate the AD834, the outputs appear
as a differential pair of currents at open collectors. To provide a
single ended ground referenced voltage output, some form of ex-
ternal current to voltage conversion is needed. This may take the
form of a wideband transformer, balun, or active circuitry such
as an op amp. In some applications (such as power measure-
ment) the subsequent signal processing may not need to have
high bandwidth.
The transfer function is accurately trimmed such that when
X = Y =
±
1 V, the differential output is
±
4 mA. This absolute
calibration allows the outputs of two or more AD834s to be
summed with precisely equal weighting, independent of the
accuracy of the load circuit.
The AD834J is specified for use over the commercial tempera-
ture range of 0°C to +70°C and is available in an 8-lead DIP
package and an 8-lead plastic SOIC package. AD834A is avail-
able in cerdip and 8-lead plastic SOIC packages for operation
over the industrial temperature range of –40°C to +85°C. The
AD834S/883B is specified for operation over the military tem-
perature range of –55°C to +125°C and is available in the 8-lead
cerdip package. S-Grade chips are also available.
REV. C
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.
Two application notes featuring the AD834 (AN-212 and
AN-216) can now be obtained by calling 1-800-ANALOG-D.
For additional applications circuits consult the AD811 data sheet.
PRODUCT HIGHLIGHTS
l. The AD834 combines high static accuracy (low input and
output offsets and accurate scale factor) with very high band-
width. As a four-quadrant multiplier or squarer, the response
extends from dc to an upper frequency limited mainly by
packaging and external board layout considerations. A large
signal bandwidth of over 500 MHz is attainable under opti-
mum conditions.
2. The AD834 can be used in many high speed nonlinear
operations, such as square rooting, analog division, vector
addition and rms-to-dc conversion. In these modes, the
bandwidth is limited by the external active components.
3. Special design techniques result in low distortion levels (better
than –60 dB on either input) at high frequencies and low signal
feedthrough (typically –65 dB up to 20 MHz).
4. The AD834 exhibits low differential phase error over the input
range—typically 0.08° at 5 MHz and 0.8° at 50 MHz. The
large signal transient response is free from overshoot, and has
an intrinsic rise time of 500 ps, typically settling to within 1%
in under 5 ns.
5. The nonloading, high impedance, differential inputs simplify
the application of the AD834.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
World Wide Web Site: http://www.analog.com
Fax: 781/326-8703
© Analog Devices, Inc., 2000
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