Suggest me a DC Level Shifter

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moisiad

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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
 

dc level shifting

is your signal differential or single-ended?
 

dc level shift


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

Regards,
Davood.
 

source follower level shifter


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.
 

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...
 

simple dc level shifter

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

level shifting with source follower

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

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