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elektroda.net NewsGroups Forum Index - Electronics Equipment - **T PHL and T PLH: why can they be different?**

Guest

Tue Jan 11, 2011 4:54 pm

Hi,

Consider the propagation time from H (high) to L (low): T PHL.

Consider the propagation time from L to H: T PLH. Why are they

generally different (in value)? Note that I'm not here speaking about

the propagation delay, T PD defined as max(T PHL, T PLH).

Thanks.

Guest

Tue Jan 11, 2011 4:54 pm

Merciadri Luca wrote:

Hi,

Consider the propagation time from H (high) to L (low): T PHL.

Consider the propagation time from L to H: T PLH. Why are they

generally different (in value)? Note that I'm not here speaking about

the propagation delay, T PD defined as max(T PHL, T PLH).

Thanks.

Consider the propagation time from H (high) to L (low): T PHL.

Consider the propagation time from L to H: T PLH. Why are they

generally different (in value)? Note that I'm not here speaking about

the propagation delay, T PD defined as max(T PHL, T PLH).

Thanks.

Did you read anything about how the circuits work? Look for asymmetries

in the device properties and circuit topology.

Hint: the physics of PMOS and NMOS devices are not as similar as they

might seem.

Cheers

Phil Hobbs

--

Dr Philip C D Hobbs

Principal

ElectroOptical Innovations

55 Orchard Rd

Briarcliff Manor NY 10510

845-480-2058

email: hobbs (atsign) electrooptical (period) net

http://electrooptical.net

Guest

Tue Jan 11, 2011 5:53 pm

On Jan 11, 4:12 pm, Phil Hobbs

<pcdhSpamMeSensel...@electrooptical.net> wrote:

Merciadri Luca wrote:

Hi,

Consider the propagation time from H (high) to L (low): T PHL.

Consider the propagation time from L to H: T PLH. Why are they

generally different (in value)? Note that I'm not here speaking about

the propagation delay, T PD defined as max(T PHL, T PLH).

Thanks.

Did you read anything about how the circuits work? Look for asymmetries

in the device properties and circuit topology.

Hint: the physics of PMOS and NMOS devices are not as similar as they

might seem.

Cheers

Phil Hobbs

--

Dr Philip C D Hobbs

Principal

ElectroOptical Innovations

55 Orchard Rd

Briarcliff Manor NY 10510

845-480-2058

email: hobbs (atsign) electrooptical (period) nethttp://electrooptical.net

Hi,

Consider the propagation time from H (high) to L (low): T PHL.

Consider the propagation time from L to H: T PLH. Why are they

generally different (in value)? Note that I'm not here speaking about

the propagation delay, T PD defined as max(T PHL, T PLH).

Thanks.

Did you read anything about how the circuits work? Look for asymmetries

in the device properties and circuit topology.

Hint: the physics of PMOS and NMOS devices are not as similar as they

might seem.

Cheers

Phil Hobbs

--

Dr Philip C D Hobbs

Principal

ElectroOptical Innovations

55 Orchard Rd

Briarcliff Manor NY 10510

845-480-2058

email: hobbs (atsign) electrooptical (period) nethttp://electrooptical.net

Thanks!

Guest

Wed Jan 12, 2011 12:11 am

Merciadri Luca wrote:

Consider the propagation time from H (high) to L (low): T PHL.

Consider the propagation time from L to H: T PLH. Why are they

generally different (in value)? Note that I'm not here speaking about

the propagation delay, T PD defined as max(T PHL, T PLH).

Generally, because bipolar transistors aren't symmetrical, top to

bottom.

These days, with CMOS, that difference is being eroded.

Hope This Helps!

Rich

elektroda.net NewsGroups Forum Index - Electronics Equipment - **T PHL and T PLH: why can they be different?**