Channel Charge Capacitance

Take Aways :

CGCCGCSCGCDCGCB
CutoffCox.W.L00CGC
Linear(Cox.W.L)/2CGCCGC0
Saturation2(Cox.W.L)/3CGC00

Interesting Facts

  • C_{ox} = \frac{e_{ox}}{t_{ox}}

Reference

Others

Capacitance generated between Channel(Source, Drain, Bulk) and Gate.

In cutoff there isn’t any channel present and therefore there is Cgc between gate and body.

In linear region inversion layer if formed. The Layer is between source and drain. Thus gate to body capacitance is 0 and total Cgc is distributed evenly between source and drain.

In saturation mode, channel is pinched off and Capacitance between gate and drain is 0 and gate and body is 0 this there is capacitance gate and source.

CGCCGCSCGCDCGCB
CutoffCox.W.L00CGC
Linear(Cox.W.L)/2CGCCGC0
Saturation2(Cox.W.L)/3CGC00

Diffusion Capacitance Model

Take Aways :

  • C_{bottom} = C_{j}.W.L_{source}
  • C_{gw}= C_{jsq}x(W+2L_{source})
  • C_{diff}= C_{gw} + C_{bottom}
  • Drain – $latex C_{diff} = C_{j}L_{drain}W + C_{jsw}(W+2L_{drain})
  • Source – $latex C_{diff} = C_{j}L_{source}W + C_{jsw}(W+2L_{source})

Reference

Junction Capacitance–Reverse biased source-body and drain-body pn junctions.

Non Linear

Decreases when reverse bias is increased.

One thought on “Parasitic Capacitance Models

Leave a Reply

%d bloggers like this: