i need help with multistage amplifier plz

Thread Starter

CoMPiLeR

Joined May 28, 2007
3
hello

can any one help me with suggesting a good configuration (cascode,cascade,common emitter,differential etc...) to get a voltage Gain of 1000 v/v?

i tried 4 stages but it didnt workout for me!

best regards,
 

Thread Starter

CoMPiLeR

Joined May 28, 2007
3
my current configuration is (Differential - Cascade - Common Emitter (emitter Resistance) - Common Emitter (Emitter Resistance)) i got Av=4 k v/v and input and output impendace as desired but am having triuble with Flow and Fhigh :S
 

Thread Starter

CoMPiLeR

Joined May 28, 2007
3
thanx for the link..i hecked it out but i need to build it not using op-amps but BJTs...
i only have problem with Flow now..i need it less than 200Hz...when i add couplin capcitor to the input signal i loose my gain :S!
 

Ron H

Joined Apr 14, 2005
7,012
Changing Flow is simply a matter of changing capacitor values. Achieving high bandwidth (Fhigh) and high gain is much more challenging. You can get more bandwidth by:
1. Using more lower gain cascaded stages.
2. Increasing power dissipation. This works because unwanted capacitance (Ccb, etc.) is relatively constant as a function of collector current, but resistor values go down, improving the high-frequency response.
3. Using cascode stages to minimize the Miller effect.
 

hgmjr

Joined Jan 28, 2005
9,029
Can you post a schematic of the amplifier configuration that you have at the moment?

Maybe we can then verify our suspicions as to the cause of your Flow problem.

hgmjr
 
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