MC3303 - MC3403 - MC3503
5/10
CIRCUIT DESCRIPTION
The MC3403 is made using four internally com-
pensated, two-stage operational amplifiers. The
first stage of each consists of differential input de-
vices 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 shifting and transonductance reduction
functions. By reducing the transconductance a
smaller compensation 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 com-
mon-mode range can include the negative supply
fo ground, in single supply operation, without sat-
uration either the input devices or the differential
to single-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 op-
erations. This is possible because class AB oper-
ation is utilized.
Each amplifier is biased from an internal voltage
regulator which has a low temperature coefficient
thus giving each amplifier good temperature char-
acteristics as well as excellent power supply rejec-
tion.
TYPICAL PERFORMANCE CURVES
APPLICATION INFORMATION
VOLTAGE REFERENCE
WIEN BRIDGE OSCILLATOR
20µs/div.
A
V
= 100
1/4
MC3403
V
O
V
CC
V
CC
R1
10kΩ
V
O
=
V
CC
1
2
V
O
R1
R1 + R2
V
CC
=
R2
10kΩ
50kΩ
5kΩ
10kΩ
1/4
MC3403
V
O
V
CC
V
(ref)
R
C
C
R
V
(ref)
=
1
2
V
CC
f
O
=
1
2 π RC
For
f
O
= 1kHz
R = 16kΩ
C = 0.01µF
