Suggest me a DC Level Shifter

[moisiad]

Hi all
Can you please suggest me a DC level shifter. I want to shift a signal with a DC Level=2V and peak-to-peak voltage 0.35V to a signal with DC Level=0.5V and the same peak-to-peak voltage.

What is critical is to keep the signal swing, while changing the DC level. I have tried the source follower but the output signal was reduced by -4.5db, which is no acceptable by the application.

Thanks

 

[darkk]

dc level shifting

is your signal differential or single-ended?

 

[Davood Amerion]

dc level shift

Hi all
Can you please suggest me a DC level shifter. I want to shift a signal with a DC Level=2V and peak-to-peak voltage 0.35V to a signal with DC Level=0.5V and the same peak-to-peak voltage.

What is critical is to keep the signal swing, while changing the DC level. I have tried the source follower but the output signal was reduced by -4.5db, which is no acceptable by the application.

in the source follower you can use one capacitor (0.1uF) between source and gate to get 0dB attenuation.

Regards,
Davood.

 

[ricklin]

source follower level shifter

Hi all
Can you please suggest me a DC level shifter. I want to shift a signal with a DC Level=2V and peak-to-peak voltage 0.35V to a signal with DC Level=0.5V and the same peak-to-peak voltage.

What is critical is to keep the signal swing, while changing the DC level. I have tried the source follower but the output signal was reduced by -4.5db, which is no acceptable by the application.

Thanks

I think source follower is ok, but large gm and high resistance of the biasing current source is needed ( gm.r >> 1, passive resistors about the 1/gm order will cause anttenuation)

Or you can use linear transconductor and use adequate passive resistors to terminate the output current, and it's easy to control the gain.

 

[fendy]

pmos source follower level shifter

The source follower gain:
Av=Rs/(1/gm+Rs),we can find,
increase the gm ,the gain ~=1,
or you can increase the Rs,the gain~=1
In fact ,the gain of source follower <1,forever...

 

[fendy]

simple dc level shifter

Yes,we can gain 0dB attenuation use gate and source capacitor .
BTW:0.1uF is too huge,10pF is enough.

 

[montage3000]

level shifting with source follower

source follow is hasr to control DC level,but it is simple