Oxide properties on frequency

Hi Guys/ladies, How oxide properties besides mobility at MOS technology can impact cut off frequencies between PMOS and NMOS? Just curious

Asked By: waijengwen
On: Apr 20, 2005 1:53:46 AM

Comments(4)

HI Waijengwen, apart from the Coxide there is another capacitance that is in series woth the above that is Cdep.this is caused due to the DEPLETION caused in the Psubstrate(NMOS) upon the application of a positive voltage.The same phenomena found in VARICAP diodes. so apart from the Th value increment the substrate voltage affects the capacitance due to depletion.more -ve the value more the capacitance. so total Cgate=Coxide.Cdep/(Coxide+Cdep) bye

Comment By: venkateshr
On: Apr 21, 2005 3:15:31 AM

Er will not be affected by P or N substrate . i think.how that will be affected.suggest me please. i only know that substrate(voltage) affects the threshold voltage value not he capacitance. correct me if iam wrong Waijengwen. Thank you.

Comment By: venkateshr
On: Apr 21, 2005 3:10:01 AM

hi Venkateshr, You mean that as capacitance varies which due to proportionality to relative permittivity, the delay time also varies which mean as capacitance of the oxide increase the delay time also increase but i think that Er will affected by P or N substrate which will affecting threshold votage of the MOS Transistor. Any advise?

Comment By: waijengwen
On: Apr 20, 2005 2:18:39 AM

as oxide props vary there will be variations in Er i.e relative permitivity thereby the capacitance varies proportionaly.but i dont think that his will vary between p and nmos.

Comment By: venkateshr
On: Apr 20, 2005 2:08:40 AM

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