500 MHz Four-Quadrant Multiplier
Data Sheet
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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
FUNCTIONAL BLOCK DIAGRAM
00894-001
AD834
CURRENT
AMPLIFIER
(W)
±4mA
FS
X1
X2
Y2
Y1
W1
V TO I
V TO I
8.5mA
8.5mA
W2
DISTORTION
CANCELLATION
DISTORTION
CANCELLATION
7
8
2
5
4
1
Figure 1.
GENERAL DESCRIPTION
The AD834 is a monolithic, laser-trimmed four-quadrant analog
multiplier intended for use in high frequency applications, with
a transconductance bandwidth (R
L
= 50 Ω) 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 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 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 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 AD834 devices
to be summed with precisely equal weighting, independent of
the accuracy of the load circuit.
The AD834J, available in 8-lead PDIP and plastic SOIC packages, is
specified over the commercial temperature range of 0°C to 70°C.
The AD834A is also available in 8-lead CERDIP and plastic SOIC
packages operating over the industrial temperature range of
−40°C to +85°C. The AD834SQ/883B, available in an 8-lead
C E R D I P, operates over the military temperature range of −55°C
to +125°C. S-grade chips are also available.
Two application notes featuring the AD834 (AN-212 and AN-216)
can be found at www.analog.com. For additional applications
circuits, consult the AD811 data sheet.
PRODUCT HIGHLIGHTS
1. Combines high static accuracy (low input and output
offsets and accurate scale factor) with very high bandwidth.
As a four-quadrant multiplier or squarer, the response
extends from dc to an upper frequency limited by packaging
and external board layout considerations. Obtains a large
signal bandwidth of >500 MHz under optimum conditions.
2. 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. 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.
