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double guard-ring in driver & pre-driver (Read 7378 times)

newic Senior Member Offline Posts: 138	double guard-ring in driver & pre-driver Oct 19^th, 2011, 10:49pm normally double guard-ring is added in the IO driver which has large current. How about pre-driver? Should guard-ring be added into the pre-driver. Predriver consume average current about 1.5mA.
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raja.cedt Senior Fellow Offline Posts: 1516 Germany	Re: double guard-ring in driver & pre-driver Reply #1 - Oct 20^th, 2011, 12:25am what do you mean by double ring driver? is it h-bridge driver?
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newic Senior Member Offline Posts: 138	Re: double guard-ring in driver & pre-driver Reply #2 - Oct 20^th, 2011, 12:49am inverter based voltage driver which is very noisy as compared to current driver. double guard-ring is added to protect latch up issue
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raja.cedt

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Re: double guard-ring in driver & pre-driver
Reply #3 - Oct 20^th, 2011, 12:54am

so double gaurd is layout rite, so no need to care from ckt point of view? So your's is voltage mode driver, so pre-drivers also kind of inverter based sturctre. To be frank i didn't understand the question. Because you are telling pre-driver consumes 1.5ma, and again you are asking wht about pre-driver...!!

Thanks,
Raj.

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newic Senior Member Offline Posts: 138	Re: double guard-ring in driver & pre-driver Reply #4 - Oct 20^th, 2011, 1:04am question: "Should guard-ring be added into the pre-driver." which this pre-drive consume about 1.5mA
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loose-electron Senior Fellow Offline Best Design Tool = Capable Designers Posts: 1638 San Diego California	Re: double guard-ring in driver & pre-driver Reply #5 - Oct 21^st, 2011, 5:58am explicitly define your circuit explicitly define what the circuit is supposed to do explicitly define your layout explicitly define your voltages, currents frequency ask the question without the above information its impossible to answer the question
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vp1953

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Re: double guard-ring in driver & pre-driver
Reply #6 - Oct 22^nd, 2011, 9:54am

Hi Newic,

It probably does not hurt to have a double guard ring around the pre-driver. Aside from latch up prevention, it also helps to keep substrate currents confined to the local area, a factor that is of importance if the IO driver is sourcing large currents. 1.5mA does not seem like a huge current but if there are VCO's, bias generators etc in close proximity, having a double guard ring around the predriver would be helpful.

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chaojixin

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Re: double guard-ring in driver & pre-driver
Reply #7 - Nov 6^th, 2011, 6:25pm

newic wrote on Oct 20^th, 2011, 12:49am:

inverter based voltage driver which is very noisy as compared to current driver.

double guard-ring is added to protect latch up issue

Hi, may I ask how to determine the width of guard-ring to prevent the latch-up? how to do the calculation, and what tools is needed?

thanks!

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loose-electron Senior Fellow Offline Best Design Tool = Capable Designers Posts: 1638 San Diego California	Re: double guard-ring in driver & pre-driver Reply #8 - Nov 7^th, 2011, 1:08pm foundry will have physical design rules for latch-up These are minimum. Suggest that substrate grounds and N-well rings be connected back to metal ground-power bias connection as much as possible.
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chaojixin Junior Member Offline Posts: 11 Shanghai	Re: double guard-ring in driver & pre-driver Reply #9 - Nov 9^th, 2011, 4:55pm thank you very much!
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