Hi, all: this circuit can generate bias voltage, but I do not know what is the role that some MOS transistor plays.
In this circuit, I want to know what is the role that M18, M51, M20 play? at the same time, what is the role that resistance R3, R2 play? what is the role that M56 and M57 play?
This circuit can generate bias voltage for an ADC, so I think this circuit is important for me. Help me, Please!!!
Hi, JT: I am sorry to disturb you again! at first, I acknowloedge you for your help.
At the same time, this circuit is certainly has no M20, but there has M56. In fact, M56 is on the right side of R2 and R3, whose gate connects with R2 and R3. M58 is on the right side of M56, whose gate connects with the drain of M56, and M57 is underneath of the M56.
So I think I can know the role of M56 from you. Help me, please!!
Firstly, i want to say that you will no waste others points when you ask question by downloading your attachment.
In this circuit, I am not clear about the function of VB3.
It is a feeback signal, but i can not find the feeback loop.
I guess:
The bias may be used for biasing thegain-boost fold-cascode full differential amplifer.
VBP1,VBP2 bias the upper load current mirror;
VBN1,VBN2 bias the bottom load current mirror;
VB1 & VB4 bias the gain-boost amplifer.
VBP & VBN bias the amplifer current source.
M18-M51-M53 is a feedback loop which is used to make the VBP is insensitive.
Just use the Vgs voltage difference betwwen the M56 & M57 and the M58 to get a voltge which drop on the resistor R4 to get a bias VB3 which is propotional to variation with threshold of MOS.
Therefore, decrese the sensitivity of power supply .