Looking for a CMOS current source

[katrin]

are there any CMOS current source which can be used?

 

[freetofree]

Re: A robust CMOS current source

increase the output resistance?

 

[dreamteam]

Re: A robust CMOS current source

this is a feedback loop. M38 and m39 are connected to ensure a negative feedback loop. This is why this scheme is stable. Without M38 you dont have a current source.

See razavi or p allen book to understand.

 

[crossbow_123]

Re: A robust CMOS current source

I find such kind of CMOS current source is very stable
and it is also very robust to the process and temperature variations

From my understanding, transístor MN39 itself and the resistor R14 can already determine the current, why do we still need another transistor MN38 in this case?

Hi
If the gate of MN39 decrese, The gate (source of MN39) of MN38 will increse, and so will increase the drain of MN38 ( the gate of MN39).

Best regards
Ben

 

[MI3talk]

Re: A robust CMOS current source

wondering what kind of model u are using in this current source configuration? Is Vbb directly connected to ground? Also, what's the supply voltage source? How will it different if I have a different Vdd, I mean in terms of W/L ratio of both device? Thanks!

 

[rock_zhu]

A robust CMOS current source

i think the current will change as vdd change.

 

[katrin]

Re: A robust CMOS current source

wondering what kind of model u are using in this current source configuration? Is Vbb directly connected to ground? Also, what's the supply voltage source? How will it different if I have a different Vdd, I mean in terms of W/L ratio of both device? Thanks!

The supply voltage is connected at the right side to R13, Vdd
The current generated in the left path is intended to be used as current source

1, The current is different when there is a different Vdd

2, the current also increases as W/L of both devices increases, because the current=Vgs(MN39)/R14, when W/L increases, Vgs(MN39) increases. But the change of current is not very significant