Whats the use of MN2, MN1 and MP1 in attached circuit?

[jordan76]

help on circuit analysis

In the circuit attached,what is the use of MN2? and the use of MN1,MP1?
Could anyone give me some clues?

regards,
jordan76

 

[guamak_menanak]

Re: help on circuit analysis

MN2 is a active resistor! I still don't have an idea the main reason why it is being used! Maybe to set the current or node voltage!

MN1 and MP1 is the driver circuit! They amplified the signal to have better result!

 

[kyrandia]

Re: help on circuit analysis

MN1 and MP1 is a class ab driver, and MN2 is float current source, it provide bias for MN1 and MP1.

 

[jetset]

Re: help on circuit analysis

I think that MN1 and MP1 are a CMOS inverter. MP2 is an active load that determines the input at the gate of the inverter.

 

[billchen]

Re: help on circuit analysis

i am confused that where is the input signal?

 

[jordan76]

Re: help on circuit analysis

As kyrandia and guamak_menanak said, I got the same answer for MN1 and MP1.
Actually they are source follower to drive the output.

But I still find no reason for the usage of MN2.
It seems ok if I delete MN2.
Any guru help me out?

billchen,
The input signal is VCC, the power supply.

regards,
jordan76

 

[sunking]

Re: help on circuit analysis

Use translinear theory, you will find more about the circuit

 

[jordan76]

Re: help on circuit analysis

sunking,

My question is what is the usage of MN2?

Could you elaborate your translinear theory a little bit?
More detail is of great help. Thanks!

regards,
jordan76

 

[guamak_menanak]

Re: help on circuit analysis

You can examine the use of MN2 by put it out from the circuit!
As I mention before, MN2 and MP2 are use to set the bias voltage, and there are active resistor! REsistor if is connected in parallel wil give R1*R2/R1+R2! So, you need to change the value of MP2 to ensure the circuit is still function as before and give the same bias voltage, without having MN2!

Now you can analyze the important of MN2 by comparing between this 2 result!

Hope this could help a little bit... :lol:

 

[jordan76]

Re: help on circuit analysis

guamak_menanak,
Thanks for your help!

I guess MN2 may be helpful to increase the driving capability of MP1.

regards,
jordan76

 

[xinsu]

help on circuit analysis

I agree with guamak_menanak's analysis, and the Resistor value should be R1*R2/(R1+R2),is it right?

 

[eda4you]

Re: help on circuit analysis

Maybe it's necessary to avoid unwanted states at the output during power-on.