MC3303 - MC3403 - MC3503

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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.

1/4

MC3403

R1

10k

Ω

1

2

R1

R1 + R2

=

R2

10k

Ω

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