designing amplifier

[ushio]

to may it may concern,
i'm studying in electrical engineering. my lecturer wanted us to design an amplifier ( a big one). the problem is i don't know where to start? the amplifer consists of first stage, level shifter, current source circuit. he don't want us to copy from the internet or any company design( if not the mark will be 0%). thank you.

 

[kinjalgp]

What kind of amplifier you want to design audio/RF ? Is is transistor/MOSFET based or IC based? What is the power requirement? Is it single ended or differential? Please clear all this points so it is easy to guide you.

 

[ushio]

requirement

these are the requirement needed:
differential mode gain> 80,000
common mode gain > 0.2
CMRR >90 dB
Output current capability < 10 mA
Power dissipation < 250 mW

these operational amplifier input stage, level shifter, output stage and constant current source.
well, i'm thinking of using 2 differential amplifier and a darlington circuit for the input stage but i don't know how to connect them properly.

tq.

 

[kinjalgp]

If your are constructing Op-amp using transistors and other components then datasheet of any op-amp will help you. Most of the manufacturers give internal circuit diagram of the op-amp which you can use as reference. Look for 741 op-amp's datasheet. Its the most widely used general purpose op-amp and internal circuit is also small.

 

[ushio]

well, i can't use op amp...i only can use amplifier such as darlington circuit, cascode circuit or mirrored circuit( i think that is it's name). i want a simpler one so i can use electronic bench software to simulate it.

 

[kinjalgp]

Well, i am not asking you to use op-amp but to construct a circuit using transistors which is inside the op-amp. For example if you consider the internal circuit of 741 op-amp, the first stage is a differential amplifier, then the level shifter, current source, power amplifier etc. Refer to internal circuit diagram of 741. It is given in the datasheet.