MC3303 - MC3403 - MC3503
CIRCUIT DESCRIPTION
The MC3403 is made using four internally compen-
sated, two-stage operational amplifiers. The first
stage of each consists of differential input devices
Q24 and Q22 with input buffer transistors Q25 and
Q21 and the differential to single ended converter
Q3 and Q4. The first stage performs not only the first
stage gain function but also performs the level shift-
ing and transconductance reduction functions. By
reducing the transconductance a smaller compen-
sation capacitor (only 8pF) can be employed, thus
saving chip area.
The transconductance reduction is accomplished
by splitting the collectors of Q24 and Q22. Another
feature of this input stage is that the input common-
mode range can include the negative supply of
TYPICAL PERFORMANCE CURVES
ground, in single supply operation, without satura-
tion either the input devices or the differential to sin-
gle-ended converter.
The second stage consists of a standard current
source load amplifier stage. The output stage is
unique because it allows the output to swing to
ground in single supply operation and yet does not
exhibit any crossover distortion in split supply opera-
tions. This is possible because class AB operation
is utilized.
Each amplifier is biased from an internal voltage
regulator which has a low temperature coefficient
thus giving each amplifier good temperature charac-
teristics as well as excellent power supply rejection.
20µs/div.
A
V
= 100
APPLICATION INFORMATION
VOLTAGE REFERENCE
V
CC
R2
10kΩ
WIEN BRIDGE OSCILLATOR
50kΩ
V
CC
10kΩ
5kΩ
V
CC
1/4
MC3403
V
O
V
(ref)
1/4
MC3403
V
(ref)
= 1 V
CC
2
V
O
f
O
=
For
R
R
C
C
1
2
π
RC
f
O
= 1kHz
R = 16kΩ
C = 0.01µF
R1
10kΩ
V
O
=
R1
V
CC
R1 + R2
V
O
= 1 V
CC
2
5/11
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