scaling of mos circuits n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Scaling of MOS circuits PowerPoint Presentation
Download Presentation
Scaling of MOS circuits

Loading in 2 Seconds...

play fullscreen
1 / 20

Scaling of MOS circuits - PowerPoint PPT Presentation


  • 201 Views
  • Uploaded on

Scaling of MOS circuits. ( Pucknell p: - 113-133). What is Scaling? Proportional adjustment of the dimensions of an electronic device while maintaining the electrical properties of the device. Impact of scaling is characterized in terms of several indicators: Minimum feature size

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Scaling of MOS circuits' - hoang


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
scaling of mos circuits

Scaling of MOS circuits

(Pucknell p:- 113-133)

slide2

What is Scaling?

  • Proportional adjustment of the dimensions of an electronic device while maintaining the electrical properties of the device
slide3

Impact of scaling is characterized in terms of several indicators:

  • Minimum feature size
  • Number of gates on one chip
  • Power dissipation
  • Maximum operational frequency
  • Die size
  • Production cost
scaling models
Scaling Models
  • Full Scaling (Constant Electrical Field)
  • Ideal model – dimensions and voltage scale together by the same scale factor
  • Fixed Voltage Scaling
  • Most common model until recently – only the dimensions scale, voltages remain constant
  • General Scaling
  • Most realistic for today’s situation – voltages and dimensions scale with different factors
scaling factors for device parameters
Scaling Factors for Device Parameters
  • Device scaling modeled in terms of generic scaling factors: 1/α and 1/β
  • 1/ β : scaling factor for supply voltage VDD and gate oxide thickness D
  • 1/α: linear dimensions both horizontal and vertical dimensions
slide7

Gate area Ag

Where L: Channel length and W: Channel width and both are scaled by 1/α

  • Thus Ag is scaled up by 1/α2
slide8

Gate capacitance per unit area Co or Cox

Where εox is permittivity of gate oxide(thin-ox)= εins εo and D is the gate oxide thickness scaled by 1/ β

  • Thus Cox is scaled up by
slide9

Gate capacitance Cg

Thus Cg is scaled up by β * 1/α2 = β/α2

  • Parasitic capacitance Cx
  • Cx is proportional to Ax/d

where d is the depletion width around source or drain and scaled by 1/ α

Ax is the area of the depletion region around source or drain, scaled by (1/α2 ).

  • Thus Cx is scaled up by
slide10

Carrier density in channel Qon

  • where Qon is the average charge per unit area in the ‘on’ state.
  • Co is scaled by β and Vgs is scaled by 1/β
  • Thus Qon is scaled by 1
slide11

Channel Resistance Ron

  • Where μ = channel carrier mobility and assumed constant
  • Thus Ron is scaled by 1
slide12

Gate delay Td

  • Td is proportional to Ron*Cg
  • Td is scaled by
slide13

Maximum operating frequency fo

  • fo is inversely proportional to delay Td and is scaled by
slide14

Saturation current Idss

  • Both Vgs and Vt are scaled by (1/β). Therefore, Idss is scaled by
slide15

Current density, J= Idss/A

  • where A is cross sectional area of the
  • Channel in the “on” state which is scaled by (1/ α 2)
  • So, J is scaled by
slide17

Power dissipation per gate Pg

  • Pg comprises of two components: static component Pgs and dynamic component Pgd:

Where, the static power component is given by:

And the dynamic component by:

Since VDD scales by (1/ β) and Ron scales by 1, Pgs scales by (1/ β2).

Since Eg scales by (1/ α2β ) and fo by (α2 / β), Pgd also scales by (1/ β2).

Therefore, Pg scales by (1/ β2).