EL4083CS INTERSIL [Intersil Corporation], EL4083CS Datasheet - Page 8

• Manufacturer Part Number: EL4083CS
• Description: Current Mode Four Quadrant Multiplier
• Manufacturer: INTERSIL [Intersil Corporation]

I
The I
ground current inputs that accept bipolar signals. The input
referred clip value is equal to I
has been chosen to be 1.25 × I
and linearity performance. Operating at higher full scale values
will degrade these two parameters and, to some extent,
bandwidth while improving the signal to noise performance,
feedthrough and control range.
The EL4083 is fundamentally different from conventional
voltage mode multipliers in that the available input range can
be tailored to accommodate voltage sources of almost any size
by selecting appropriate input series resistor values. If desired,
one can interface with voltages that are much greater than the
supplies from which the part is powered. Current source signals
can be connected directly to the multiplier inputs. The parts’
dynamic range can also be tailored to a large extent for a
current signal by the appropriate selection of I
act in the same manner as a virtual ground input of an
operational amplifier and thus can serve as a summing node for
any number of voltage and/or current signals. Outputs of
components such as current output DACs, transconductance
amplifiers and current conveyors can be directly connected to
the inputs.
Ideally, a multiplier should give zero output if either one of its
multiplying inputs is zero. A nonzero output under these
conditions is caused by a combination of input and output
referred offsets. An output referred offset can be thought of as
a fixed value added to the output and thus only affects D.C.
accuracy. An input referred offset at a multiplying input allows
signal to feedthrough from the other multiplying input to the
output(s). The EL4083 is trimmed during testing at Elantec for
X and Y input referred offset for I
networks provide a current to each input which nulls the
feedthrough caused by internal device mismatches. These
current values are ratioed to the value of I
referred nulls are largely maintained at different values of I
However, there will be some mistracking in the trim networks so
that the input referred null point will deviate away from zero at
values of I
input and output referred offset trim networks which can be
used as needed to improve performance.
As mentioned, the output referred offset only affects D.C.
accuracy which may not be an issue in A.C. applications. In
X
and I
X
and I
Y
Z
(Multiplier) Inputs and Offset Trimming
lower than 1.6mA. Figure 9 shows optional external
Y
pins are low impedance (I
8
Z
Z
× 2 while the full scale value
to maintain excellent distortion
Z
= 1.6 mA. The internal trim
Z
Z
dependent) virtual
so that the input
Z
. These inputs
Z
EL4083
.
gain control applications one may only need to null feedthrough
with respect to the gain control input.
In gain control (VCA) applications the X input should be used
as the control input and the signal applied to the Y input since it
has slightly higher bandwidth and better linearity and distortion
performance.
Current Outputs (I
Distortion
Another unique feature of the EL4083 is the differential ground
referenced current output structure. These outputs can drive
50Ω terminated lines and reactive loads such as transformers,
baluns, and LC tank and filter circuits directly (See EL2082
Data Sheet_Receiver IF Amplifier (Figure 19). The EL2082 also
has a current output.). Unlike low impedance follower buffers,
these outputs do not interact with the load to produce ringing or
instability. If a high level low impedance output is required, the
outputs can be recovered differentially and converted to a
single ended output with a fast op amp such as the EL2075
(see Figure 19). The outputs can also drive current input
devices such as CMF amps, current conveyors and its own
inputs directly by simple connection.
Figures 12 and 14 show the nulled gain and feedthrough
characteristics of the I
identical and differ only in phase. Figure 12 is with the A.C.
signal applied to the X input with Y used as the gain control and
in Figure 14 these signals are reversed. Note that in both cases
the signal feedthrough rolls up and peaks near the cutoff
frequency. This is quite typical of the performance of all
previous four quadrant multipliers. Figures 13 and 15 show the
corresponding gain/feedthrough characteristics for the
differentially recovered output signal I
case the peak feedthrough at high frequencies is lower by more
than 40dB (See EL2082 Data Sheet - Receiver IF Amplifier
[Figure 19]. The EL2082 also has a current output).
General Operating Information
Figures 16 and 17 show the total harmonic distortion for the
single-ended and differential recovered outputs for a full scale
A.C. input signal on one input and a full scale D.C. control
signal on the other. Note that above about one megahertz to
the cutoff frequency the THD of the differentially recovered
signal is as much as 10dB lower than the single-ended signals.
XY
XY
, I
and I
XY
), Feedthrough and
XY
outputs which are virtually
XY
-I
XY
. Note that in this