How to increase the PSRR of a general amp

[fantaci]

Is there any general way to increase the PSRR of AMP?

 

[sunking]

How to decrease the PSRR of a general amp

reduce the channel length
add cap
change the structre

 

[Humungus]

Re: How to decrease the PSRR of a general amp

Do you really want to decrease the PSRR? Decrease = Worsen as opposite to "improve"

 

[SkyHigh]

Re: How to decrease the PSRR of a general amp

Why decrease PSRR and what purpose does it serve to decrease it?

Designers want to improve PSRR, as high possible.

 

[marshel]

How to decrease the PSRR of a general amp

why decrease? I can not imagine. You mean increase?

 

[fantaci]

How to decrease the PSRR of a general amp

Sorry, I made mistake.
Not decrease PSRR, but increase PSRR...

 

[Humungus]

make asearch for a paper from sackinger (it is public domain)

Other solutions are to increase the output conductance of all critical transistors, to improve matching and to reduce all capacitances contributing to PSRR

 

[boyet_919]

i think when u want to improve the psrr, you want to decrease it?
like decrease psrr from -30db to -60 db, right?

btw, when u mentioned increasing the channel length, which mos is it?
the current mirror/differential pair/load?

my understanding is that when u increase the channel width of the differential pair, you increase the open loop gain, then u also increase the psrr.

 

[eejli]

differential siganling. put decoupling capacitance in parrallel with the power vdd and vss. watch out the bonding pad inductance effect which may oscillate with the cap.

 

[pinkmouse]

You can also replace bias resistor networks with CCSs

Added after 15 minutes:

And a good review of earth routing is always sensible.

 

[jiangwp]

Maybe, the most discuss about PSRR is abut the ouput stage.

The relation between the amplifier transisor of output stage andpower supply either positive or negative in high frequency is dealed with.

Due to increase frequence making the amplifier transistor look like short the gate and drain, so the amplifier transistor of ouput stage is like a diode connection between the power supply and the ouput, thus, the output follws the power supply variation that decreses the PSRR.

So , generally, the cascade transitor of ouput stage can improve the PSRR.

Or other ways making the relation weak about the power supply and output port at high frequence are also ok.

 

[eejli]

when you put the decoupling cap it is better to put a small resistor in series with the cap to make damping on the possible resonation in the LC loop.