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# The relation between slew rate and gm

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#### chacha

##### Member level 5
Hi
slew rate = id/cc where cc = gm/wt.
gm is inv prop to slew rate.
can any body explain it intuitively??

thanks.

Re: slew rate vs gm

Hi,
Here gm is proportional to square root of Id.
so effectively S.R. is proportional to square root of Id, which is obvious.

slew rate vs gm

Slew rate is the rate of change of output voltage.
i.e., when a step input is applied, in how much time the output reaching the input in buffer configuration.

slew rate is inversely proportional to settling time. If settling time is more, slew rate is less. If the time to settle the output voltage is less, the slew rate is more.

High bandwidth is required to settle down for systems having high settling time. For systems having low settling time, have low bandwidth to accomodate.

i.e., bandwidth is directly proportional to settling time. and settling time is inversely proportional to slew rate.
so, ultimately bandwidthis inversely proportioal to slew rate.

Re: slew rate vs gm

analog_prodigy said:
Slew rate is the rate of change of output voltage.
i.e., when a step input is applied, in how much time the output reaching the input in buffer configuration.

slew rate is inversely proportional to settling time. If settling time is more, slew rate is less. If the time to settle the output voltage is less, the slew rate is more.

High bandwidth is required to settle down for systems having high settling time. For systems having low settling time, have low bandwidth to accomodate.

i.e., bandwidth is directly proportional to settling time. and settling time is inversely proportional to slew rate.
so, ultimately bandwidthis inversely proportioal to slew rate.

I don't understand why settling time is inversely proportioal to slew rate.
Setting time is a small signal behavior, and slew rate is large signal.
Could you explain it more detail?
Thank you

Re: slew rate vs gm

slew rate =Id/(C*gain) also gain bandwidth product =gm/wt as far as i remember.... can you please explain the equations u have given with full forms or explanations...

slew rate vs gm

I think if you set GBW for design, then SR can get the relationship with GBW, but if you set Current for design, SR can be set by Cm
No condition, no relation.

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