Hi all,
I want to design own simple class a amp but i don't know how to calculating the resistor & capacitor values of class a amplifier e.g. Rc,Re and Rb.
tell me how calculate these values.
Regard's
Parveen
I want to design own simple class a amp but i don't know how to calculating the resistor & capacitor values of class a amplifier e.g. Rc,Re and Rb.
tell me how calculate these values.
Regard's
Parveen
Hi Parveen
Before we can help you, we need to know what amplifier design you are referring to.
Rc,Re,Rb means nothing unless you have a circuit which shows where they are and
what they do. Post the schematic or link to it so that others can clearly see what
your problem is.
Before we can help you, we need to know what amplifier design you are referring to.
Rc,Re,Rb means nothing unless you have a circuit which shows where they are and
what they do. Post the schematic or link to it so that others can clearly see what
your problem is.
I hope you appreciate that the components around this circuit will only give you a small signal amplifier - i.e. line level. C4 isn't necessary.
You need to start with the data sheet for the transistor in question and pick the operating point that you are aiming for.
You need to start with the data sheet for the transistor in question and pick the operating point that you are aiming for.
As KatieandDad says, pick your operating point.
(This may depend on what resistance value you need for Rl.)
Then, based on thermal stability requirements:
Vre (we were taught) should be about 10% of +Vcc. ( or a volt or two in the case of +Vcc>20V)
Knowing Ic and Hfe you should be able to get Ib.
Ir2 should be 9*Ib and Ir1 is 10*Ib. (not critical but just a suggestion)
Vr2 = Vre + 0.6V (or so...from data sheet @ Ic)
Vr1 = (+Vcc - Vr2 ) / Ir1
Vrl should be about 45% of +Vcc.
Then check power dissipation for all components to see if they will be OK.
That should get you started.
🙂
(This may depend on what resistance value you need for Rl.)
Then, based on thermal stability requirements:
Vre (we were taught) should be about 10% of +Vcc. ( or a volt or two in the case of +Vcc>20V)
Knowing Ic and Hfe you should be able to get Ib.
Ir2 should be 9*Ib and Ir1 is 10*Ib. (not critical but just a suggestion)
Vr2 = Vre + 0.6V (or so...from data sheet @ Ic)
Vr1 = (+Vcc - Vr2 ) / Ir1
Vrl should be about 45% of +Vcc.
Then check power dissipation for all components to see if they will be OK.
That should get you started.
🙂
You need to get yourself a copy of Practical Analysis of Amplifier Circuits thtough Experimentation (Lorne MacDonald). That will answer all these questions and more.
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