Designer’s Guide Community

kollayliu

Junior Member

Offline

Posts: 22

Large gate resistance
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.

Back to top

Screenshot_at_2012-06-18_160004.png

« Last Edit: Jun 18^th, 2012, 8:14am by kollayliu »

IP Logged

kollayliu Junior Member Offline Posts: 22	Re: Large gate resistance Reply #1 - 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
Back to top	IP Logged

loose-electron Senior Fellow Offline Best Design Tool = Capable Designers Posts: 1638 San Diego California	Re: Large gate resistance Reply #2 - 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
Back to top	Jerry Twomey www.effectiveelectrons.com Read My Electronic Design Column Here Contract IC-PCB-System Design - Analog, Mixed Signal, RF & Medical IP Logged

ywguo

Community Fellow

Offline

Posts: 943
Shanghai, PRC

Re: Large gate resistance
Reply #3 - 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

Back to top

IP Logged

nadroit Junior Member Offline Posts: 14	Re: Large gate resistance Reply #4 - 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
Back to top	IP Logged