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Model
339A
Section VIII
Figure
8-5.
Simplified
Capacitance
Neutralizer
Schematic.
approximately
-100 dB.
To
improve
the ''notch
width",
a
8-33.
Capacitance
Neutralizer,
portion of
the
output
signal
from
A3U3
is
fed-back
to
the
notch
filter
circuit.
The
effects
of
this
feed-back
are
8-34.
The
purpose
of the
Capacitance
Neutralizer
is
to
illustrated
in
Figure
8-4.
Feed-back
amplifier
A3U4
is
a
neutralize the
effects
of
stray
capacitance
at
the
output
of
unity gain amplifier
which
provides
isolation
between
the
notch
filter.
The
neutralizer
circuit
(shown
in
Figure
notch
amplifier
A3U3
and
the
notch
filter
circuitry.
The
8-5) consists
of
an operational
amplifier
whose
gain
is
set
notch
filter
output (from
A3U3)
is
applied
to the
input of
bv
resistors
"R".
The
output
voltage of
A3U2
is
equal
distortion amplifier
A3U200
and
to
the
input of the
to:
Vf(l
+
R
R)
or
2Vf,
where
Vf
is
the
output
voltage
amplitude
and
phase
error detector
circuits.
from
the
notch
filter.
The
output
of
A3U2
drives
FROM
INPUT
BUFFER
A3UIOI
REFERENCE
AMPLITUDE
DIFFERENTIAL
TO
AMPLIFIER
Figure
8-6.
Simplified
Amplitude
Error
Detector
Schematic.
8-5
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