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Design >> RF Design >> Large gate resistance
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Message started by kollayliu on Jun 18^th, 2012, 7:02am

Title: Large gate resistance
Post by kollayliu on Jun 18^th, 2012, 7:02am

Hi all,

I'm starting with a new technology. I just noticed that the gate resistance in this technology is quite large. For example, for a regular MOSFET and a RF MOSFET both in a size of 100um/0.18um (2 fingers), the gate resistance are 458ohm and 92ohm respectively.

I'm not sure if these value are reasonable. If they are not reasonable, what do you think are the reasons for these wrong values?

Attached is my test bench.

Thanks.

Title: Re: Large gate resistance
Post by kollayliu on Jun 18^th, 2012, 7:18am

BTW, the gate resistance can be reduced by using more fingers. For example, for a RF MOSFET in a size of 100um/0.18um, following is the relationship between number of figures and gate resistance

Number of fingers Gate resistance
2 92 ohm
5 9 ohm
20 4 ohm

If these values are reasonable?

Thanks

Title: Re: Large gate resistance
Post by loose-electron on Jun 18^th, 2012, 3:04pm

what is the resistance per square of the polysilicon layer that makes the gate?

Is it a silicided polysilicon?

Silicided Poly are the most common and will be under 10 ohms per square.

Non-silicided poly runs up to 200 ohms/square

Title: Re: Large gate resistance
Post by ywguo on Jun 27^th, 2012, 6:35am

Hi Kollayliu,

It is not clear how do you get the value of gate resistance in your simulation. Could you please explain the method you measure gate resistance?

It is strange that the gate resistance for a regular MOSFET is 5 times of the gate resistance for a RF MOSFET. In fact, they have the same material in CMOS technology. So they should have equal gate resistance if their gate length/width/finger are equal to each other.

Best Regards,
Yawei

Title: Re: Large gate resistance
Post by nadroit on Jul 9^th, 2012, 12:10pm

Hello kollayliu
How did you measure gate resistance in cadence? is it from dc simulation? I do not see any gavte resistance parameter in operating point information. lease let me know

Thanks