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AD834S

500 MHz Four-Quadrant Multiplier

Analog Devices 

a

500 MHz Four-Quadrant Multiplier

AD834

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 VS = ؎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

GENERAL DESCRIPTION

The AD834 is a monolithic, laser-trimmed four-quadrant analog

multiplier intended for use in high-frequency applications, with

a transconductance bandwidth (RL = 50 W) in excess of 500 MHz

from either of the differential voltage inputs. In multiplier modes,

the typical total full-scale error is 0.5%, dependent on the appli-

cation mode and the external circuitry. Performance is relatively

insensitive to temperature and supply variations, due to the use

of stable biasing based on a band gap reference generator 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

external 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 mea-

surement) 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 temperature

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 available in

cerdip and 8-lead plastic SOIC packages for operation over the

industrial temperature range of –40∞C to +85∞C. The AD834S/

D883B is specified for operation over the military temperature

range of –55∞C to +125∞C and is available in the 8-lead cerdip

package. S-grade chips are also available.

FUNCTIONAL BLOCK DIAGRAM

X2

X1

+VS

W1

8

7

6

5

AD834

V/I

8.5mA

X-DISTORTION

CANCELLATION

MULTIPLIER CORE

Y-DISTORTION

CANCELLATION

CURRENT

AMPLIFIER

(W)

؎4mA

FS

8.5mA

V/I

1

2

3

4

Y1

Y2

–VS

W2

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.

REV. D

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 that

may result from its use. No license is granted by implication or otherwise

under any patent or patent rights of Analog Devices.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 781/329-4700

www.analog.com

Fax: 781/326-8703

© Analog Devices, Inc., 2002

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