Help me construct a 10000 v/v gain amplifier

[electricDesire]

10000 v/v gain amplifier

Hi all,
i have to design an electronic circuit using transistors with these specifications:
gain >10000 v/v
Ro<100Ω
Rin>500 kΩ
FH> 1Mhz
FL<200 Hz

it would be a nice challenge for someone. anybody can help?
even a fast hint on the types of circuits i may use and the number of stages in such a circuit and the parameter of a BJT that would achieve these specifications.

 

[IanP]

Re: 10000 v/v gain amplifier

How about using the LM741's configuration .. see picture below ..
It fulfills all conditions ..

Regards,
IanP

 

[VVV]

Re: 10000 v/v gain amplifier

For the gain you are looking for you could use a single stage with an active load (a current source, implemented with another transistor).

Since the input impedance is fairly large, I would say you should use a Darlington stage, in an emitter follower configuration. You could also use a bootstrapped input stage.

For the output, since the output impedance is fairly low, and because the gain stage needs to see a very large load to get you the gain, you probalby need another Darlington follower at the output.

So to summarize: a Darlington follower stage (or a bootstrapped stage) at the input, a gain stage with an active load, and a Darlington follower stage at the output, with a load that ensures less than 100 ohm output impedance.

Calculate the upper and lower cutoff frequencies based on the loads and the transistors' capacitances and coupling capacitances.
If you are not going for the bootstrapped version, then the circuit will work down to DC (unless you use coupling capacitors), so you just need to worry about the higher frequency limit.

 

[electricDesire]

10000 v/v gain amplifier

thank u, IanP ; im afraid if i use the configuration u offered i wouldnt be able to analyse it theoretically..
VVV, i will see if i can make it cuz its really hard to manage between the high gain and the high cutoff frequency!