EL4083C Elantec Semiconductor, Inc. (acquired by Intersil), EL4083C Datasheet - Page 8

• Manufacturer Part Number: EL4083C
• Description: Current Mode Four Quadrant Multiplier
• Manufacturer: Elantec Semiconductor, Inc. (acquired by Intersil)

General Operating Information
I
Supplies
The I
ground current input It can accept positive
current from a resistor connected to a positive
voltage source or the positive supply The instan-
taneous bias for the multiplier gain core is pro-
portional to this current value Negative applied
current will put the multiplier portion of the cir-
cuit in a zero bias state and the voltage at the pin
will be clamped at a diode drop below ground
The part will respond in a similar manner to cur-
rents from a current source such as the output of
a transconductance amplifier or one of its own
outputs The overall transfer equation for the
EL4083 is
K(I
As can be seen from the equation the Z input can
serve as a divisor input However it is different
from the other two inputs in that the value of its
current determines the supply current of the part
and the bandwidth and compliance range of the
outputs and other two inputs Table 1 gives the
equations describing these and other important
relationships These dependencies can complicate
and or limit the usefulness of this pin as a com-
putational input The I
pedance of the multiplying inputs can be particu-
larly troublesome See the I
RMS 2 circuit sections of the application note
for some ways of dealing with this
Z
EL4083C
Current Mode Four Quadrant Multiplier
Input (Bias Divisor) and Power
X c
Z
pin is a low impedance (
Positive Supply Current
Negative Supply Current
Power Dissipation (See Figures 4 and 5)
Multipling Input(s) Impedance
Multiplying Input(s) Clip Point
Multiplying Input(s) Full Scale Value
Multiplying Input Resistor Values
(In Terms of Peak Input Signal)
Full Scale Output (Single Ended)
Full Scale Output (Differential)
I
I
I
I
I
Z
Z
X
X
Y
(Bias) Input Voltage vs I
Signal Bandwidth vs I
) I
I
I
Y
Y
Signal Bandwidth vs I
1% Settling Time vs I
Z
e
(I
XY
–I
Z
Table 1 Basic Design Equations and Relationships
XY
dependence of the im-
Z
) K E 1
Z
Z
Z
Z
divider and the
k
20 ) virtual
8
The primary intended use for the Z input is as a
programming pin similar in function to those on
programmable op amps This enables one to
trade off power consumption against bandwidth
and settling time and allow the part to function
within its power dissipation rating over its full
operational supply range (
The E4083 has been designed to function well for
I
which corresponds to I
widths of about 50 MHz to over 200 MHz High-
er values of I
ture extremes while lower values down to zero
will progressively degrade the input referred D C
offsets and reduce speed Below about 50
bias current the internal servo amplifier loop
which maintains the I
regulation and the voltage at the pin will start to
move negative (see Figure 10) This is accompa-
nied by a significant increase in input imped-
dance of the pin Figure 11 shows the A C band-
width of the I
value of I
and 1% settling time of the multiplying inputs
I
I
Trimming
The I
dent) virtual ground current inputs that accept
bipolar signals The input referred clip value is
equal to I
chosen to be 1 25
tortion and linearity performance Operating at
higher full scale values will degrade these two pa-
Z
X
X
I
I
PWR
R
I
I
R
R
I
(I
(See Figure 10)
(See Figure 11)
(See Figure 6)
(See Figure 7)
values in the range of 200 A
and I
and I
S
S
X
X
XY
ZX
X
Y
XY
a e
b e
(clip)
(fs)
X
e
e
e
e
b
and I
e
V
V
e
I
Y
3 4 mA
4 5 mA
R
I
Y
X
XY
Z c
Y
Z
(
e
XY
ZY
a
I
(peak) I
(peak) I
Y
as functions of I
(Multiplier) Inputs and Offset
I
e
)
Figures 6 and 7 show the bandwidth
V
Y
(fs)
Y
e
e
S
Z
2 while the full scale value has been
I
(clip)
Z
a
a
b
X
pins are low impedance (I
(32 )
I
e
may cause problems at tempera-
X
(fs)
input as a function of the D C
I
(
I
Y
X
Z c
b
I
Z c
(fs)
c
Z c
e
(fs)
(fs)
V
c
c
S
I
c
I
27
26
))
Z
I
Z c
1 25 (nominal)
1 6 mA I
Y
I
Z
c
to maintain excellent dis-
Y
(fs) (I
X
(fs) I
pin at ground will lose
(4 mA
2
and I
Z
g
Z c
Z
Z
4 5V
a
2)
I
k
Y
Z c
I
signal band-
b
Z k
26 5)
g
Z
1 6 mA
16 5V)
depen-
A of