Explanation of using low drain capacitance in folded structure

[siddharth1501]

hi all

In folded structure we take drain as common teriminal for low capacitance.But why ?why not source

 

[ankitgarg0312]

low drain cpacitance

can you give more details on question?

 

[siddharth1501]

low drain cpacitance

why drain capacitance should be less

Added after 2 minutes:

how it is advantageous?

 

[ankitgarg0312]

low drain cpacitance

can you tell which circuit are you talking about,
if possible post a snapshot

 

[siddharth1501]

low drain cpacitance

In general i am saying any transistor with multiple fingers

 

[erasmocf]

Re: low drain cpacitance

Maybe because the source is often connected to Vdd or GND.
The charge in this capacitors will be constant and a better ripple filtering will be made.
If the drain is more capacitive the circuit will run slowly.

 

[siddharth1501]

low drain cpacitance

To some extent i agree with u .can anyone else elabroate

 

[deepak242003]

low drain cpacitance

if you take simple case of inverter...out put is at drain.. more drain area means more diffusion capacitance... this capacitance will take some time to charge and discharging resulting in delay in output ..... Hence drain capa is reduced...

-deepak

 

[siddharth1501]

Re: low drain cpacitance

hello deepak

thanks for ur reply, may i know why we capacitor at intverter output.



regards

siddu

 

[deepak242003]

Re: low drain cpacitance

hello deepak

thanks for ur reply, may i know why we capacitor at intverter output.



regards

siddu

It is drain to substrate capacitance..

 

[siddharth1501]

low drain cpacitance

wat abt source capacitance ?

 

[deepak242003]

Re: low drain cpacitance

wat abt source capacitance ?

Tis capacitance will be wiht respect to gnd.. so wont effect much..