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DAC glitch due to charging injection of switch

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godspeed.w

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I design a kind of dac and I find that due to charge injection of switch to the resistor string , the output of dac have glitch about 10mv-20mv even more .I did not know how to solve this problem,who can help me .
thanks
 

charge injection glitch time

There are several methods to reduce the charge injection effect; the least effort uses anti-phase switching of a short-circuited W/2 transistor. You'll find this method in any book about analog circuit design.

An even more successful - but more complex - method you'll find when searching for bottom-plate-sampling.
 

reducing glitch and charge injection

there are 256 resistors placed from vref to gnd and some switch behind of each res node,when one of switch is off and another switch is on the charge will be injected in the res string and the node voltage of res string will be changed ,through about 500ns the node voltage back to the initial value , this time is so long and the output voltage will be changed .this will produce the glitch.

maybe I should improve the response time of op(vref buffer)
maybe I should improve the value of res string.
maybe ..........
 

glitch dac definition

godspeed.w said:
maybe I should improve the response time of op(vref buffer)
maybe I should improve the value of res string.
maybe ..........
Click to expand...
If this is a buffer or resistor_value pb. or due to charge injection, you can find out if you use ideal (functional or behavioral) switches - just for simulation of course ;-)
 

dac glitches

sorry,I don't know what 's the meaning of yours.
this is a vref buffer and the second stage is res string load to provide equal node voltage and you can use switch to choose the node voltage to next stage.
 

glitch with dac

godspeed.w said:
sorry,I don't know what 's the meaning of yours.
this is a vref buffer and the second stage is res string load to provide equal node voltage and you can use switch to choose the node voltage to next stage.
Click to expand...
This is totally clear, godspeed. I'm sorry if you can't understand what I tried to explain. Here's a shorter explanation: An ideal switch doesn't inject charge! So you could find out if your glitch arises from charge injection - or not.
Hope this is understandable!
 

Re: about glitch of dac

Resistor string DAC? What is the value of your every singe resistor, How large of your switch, you can minimize your switch size to reduce rc time constant.
?
 

Re: charge injection glitch time

erikl said:
There are several methods to reduce the charge injection effect; the least effort uses anti-phase switching of a short-circuited W/2 transistor. You'll find this method in any book about analog circuit design.

An even more successful - but more complex - method you'll find when searching for bottom-plate-sampling.
Click to expand...

Hello erikl.

Could you give me some references about bottom plate sampling for resistor string DACs? I have read your post and then I have searched in google for some papers or book's chapter about this topic with no results.
 
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