el2082 Intersil Corporation, el2082 Datasheet - Page 12

• Manufacturer Part Number: el2082
• Description: Current Mode Multiplier
• Manufacturer: Intersil Corporation

although the V
the case of cascaded filters. The V
and peaking adjust point around the nominal 1V value. The
resistor at I
trimmed subsequently with V
Negative Components
The following circuit converts a component or two-terminal
network to a variable and even negative replica of that
impedance:
A negative impedance is simply an impedance whose
current flows reverse to the normal sense. In the above
circuit, the current through Z is replicated by the EL2082 and
inverted (I
EL2082) and summed back to the input. When V
V
V
with the input and the input impedance is “infinite”. When
V
summed with the input resulting in an input impedance of
-Z-95 .
Thus variable capacitors can be simulated by substituting
the capacitor as Z. “Negative” capacitors result for V
and capacitance needs to be present in parallel with the
input to prevent oscillations. Inductors or complicated
networks also work for Z, but a net negative impedance will
result in oscillations.
FIGURE 11. VARIABLE OR NEGATIVE IMPEDANCE
G
G
G
< 0, the input impedance is simply Z+95 . When
= 1V, the negative of the current through Z is summed
= 2V, twice the negative of the current through Z is
OUT
OUT
CONVERTER
IN
Z
flows inverted to the sense of I
I N
could serve as the frequency trim, and Q
of the next EL2082 can be driven directly in
=
-------------------------------------
1
+
Z
-V G 1V
+
95
12
GAIN
.
GAIN
input acts as a Q
IN
in the
G
= 0 or
G
> 1V,
EL2082