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

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.

CIRCUIT DESCRIPTION

20

µs/div.

TYPICAL PERFORMANCE CURVES

1/4

MC3403

R1

10k

Ω

1

2

R1

R1 + R2

=

R2

10k

Ω

APPLICATION INFORMATION

VOLTAGE REFERENCE

50k

Ω

5k

Ω

10k

Ω

1/4

MC3403

R

C

C

R

2

1

2

π RC

For

R = 16k

Ω

C = 0.01

µF

WIEN BRIDGE OSCILLATOR

MC3303 - MC3403 - MC3503

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