Kevin Aylward wrote:
gwhite wrote:
Frank Raffaeli wrote:

gwhite wrote in message
... [snipped long diatribes]



Non-linearity is *not* required to create DSB-AM out of
transconductance type multipliers like the gilbert cell.

I have nothing more to say on this. I have better things to do.

However, what the hell...:-)

We know for the diode:

gm = 40.Id.

That is, the gm or IV slope is a fuction of I. This allows another
transister to give an output:

Iout = gm.Vi

Iout = 40.Id.Vi

Which is a multiplication of Id with Vi, or a modulator.

Now, lets pretend that the diode equation is linear:

Id = Io.(1 + k.Vd)

gm is then

gm = d(Id)/d(Vd)

therefore

gm = Io.k

Thus the gm is a constant, independent of applied current or voltage.
This
means a transistor using this as a control parameter would give an
output:

Iout = gm.Vi = Io.k.Vi

Which has no multiplication factors.

To achive muliplication one can consider adding a nonlinear term

Id = Io.(1 + k.Vd + cVd^2)

gm = Io.(k + 2c.Vd)

and subsequently

Iout = Io.(k + 2c.Vd).Vi

Which does have a multiplication term.

This can be formalised. To achieve multiplication from a gm source, we
must have

Vo = gm(V1).V2.

That is, gm must be a function of V1. However, Gm is defined by Vi as

gm = dI/dVi, therefore

I = integral(gm(Vi))

If gm(Vi) is represented by a Taylor expansion, any required terms
linear in Vi will integrate to Vi^2, that is

I = aV^2 + terms...

That is, the I verses V relation must be non-linear to achieve a gm that
is a function of voltage or current.

Kevin Aylward

http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

Kevin Aylward wrote:
gwhite wrote:
Frank Raffaeli wrote:

gwhite wrote in message
... [snipped long diatribes]



Non-linearity is *not* required to create DSB-AM out of
transconductance type multipliers like the gilbert cell.

I have nothing more to say on this. I have better things to do.

However, what the hell...:-)

We know for the diode:

gm = 40.Id.

That is, the gm or IV slope is a fuction of I. This allows another
transister to give an output:

Iout = gm.Vi

Iout = 40.Id.Vi

Which is a multiplication of Id with Vi, or a modulator.

Now, lets pretend that the diode equation is linear:

Id = Io.(1 + k.Vd)

gm is then

gm = d(Id)/d(Vd)

therefore

gm = Io.k

Thus the gm is a constant, independent of applied current or voltage.
This
means a transistor using this as a control parameter would give an
output:

Iout = gm.Vi = Io.k.Vi

Which has no multiplication factors.

To achive muliplication one can consider adding a nonlinear term

Id = Io.(1 + k.Vd + cVd^2)

gm = Io.(k + 2c.Vd)

and subsequently

Iout = Io.(k + 2c.Vd).Vi

Which does have a multiplication term.

This can be formalised. To achieve multiplication from a gm source, we
must have

Vo = gm(V1).V2.

That is, gm must be a function of V1. However, Gm is defined by Vi as

gm = dI/dVi, therefore

I = integral(gm(Vi))

If gm(Vi) is represented by a Taylor expansion, any required terms
linear in Vi will integrate to Vi^2, that is

I = aV^2 + terms...

That is, the I verses V relation must be non-linear to achieve a gm that
is a function of voltage or current.

Kevin Aylward

http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

Kevin Aylward wrote:

I think you have still missed an important point here. Yes, I agree that
there is some truth in this, and this is a pretty obvious analysis, but
it is not that significant. The most important facter is good gene
stock.

Heck, I thought her strategy was to latch on to the
best provider and then during that small period of maximum
fertility sneak out and laid by the biggest baddest stud
available.

Kevin Aylward wrote:

I think you have still missed an important point here. Yes, I agree that
there is some truth in this, and this is a pretty obvious analysis, but
it is not that significant. The most important facter is good gene
stock.

Heck, I thought her strategy was to latch on to the
best provider and then during that small period of maximum
fertility sneak out and laid by the biggest baddest stud
available.

Roy McCammon wrote:
Kevin Aylward wrote:

I think you have still missed an important point here. Yes, I agree
that there is some truth in this, and this is a pretty obvious
analysis, but it is not that significant. The most important facter
is good gene stock.

Heck, I thought her strategy was to latch on to the
best provider and then during that small period of maximum
fertility sneak out and laid by the biggest baddest stud
available.

Indeed. This is essentially the way it works.

So, as far as picking up women, one must always act in such a manner as
she would want in her offspring. Walk tall, show no sign of weakness
etc... The best way to pick up a women is to make sure that your with
lots of other women. They want offspring that are similar attractive
with other women. For, men its big bad news if a women is seen with lots
of men. Too much probability that she's having someone's else genes, and
as you say, having some sucker pick upon the rearing tab.

Kevin Aylward

http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

Roy McCammon wrote:
Kevin Aylward wrote:

I think you have still missed an important point here. Yes, I agree
that there is some truth in this, and this is a pretty obvious
analysis, but it is not that significant. The most important facter
is good gene stock.

Heck, I thought her strategy was to latch on to the
best provider and then during that small period of maximum
fertility sneak out and laid by the biggest baddest stud
available.

Indeed. This is essentially the way it works.

So, as far as picking up women, one must always act in such a manner as
she would want in her offspring. Walk tall, show no sign of weakness
etc... The best way to pick up a women is to make sure that your with
lots of other women. They want offspring that are similar attractive
with other women. For, men its big bad news if a women is seen with lots
of men. Too much probability that she's having someone's else genes, and
as you say, having some sucker pick upon the rearing tab.

Kevin Aylward

http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

Frank Raffaeli wrote:

Eric,

The really efficient dsp / digital algorithms come about with
time-varying processes. Another good bit of science is the use of
recursive filters to produce a finite impulse response ... That's one
nice way to squeeze a lot of functionality in a medium-sized IC / FPGA
/ ASIC ... or whatever.

Radio receiver (demodulation) and bandpass algorithm / code get a lot
smaller.

No doubt about it! Though my point was something different.

A recursive filter would probably count as LTI since the coefficients don't
change (at least in the kind I'm thinking of). An adaptive filter, though,
might not, though it'd be time-invariant between adaptations.

A DSP / math-oriented guy would look at a mixer or modulator and say "See,
it's linear!" because the stage is a-times-b. Look, no second- or third-order
terms! An EE guy would say "it generates new frequencies, it's not linear."
The EE guy means "function of one variable that only changes the scale or
intercept".

Just terminology differences, is all it is.

Frank Raffaeli wrote:

Eric,

The really efficient dsp / digital algorithms come about with
time-varying processes. Another good bit of science is the use of
recursive filters to produce a finite impulse response ... That's one
nice way to squeeze a lot of functionality in a medium-sized IC / FPGA
/ ASIC ... or whatever.

Radio receiver (demodulation) and bandpass algorithm / code get a lot
smaller.

No doubt about it! Though my point was something different.

A recursive filter would probably count as LTI since the coefficients don't
change (at least in the kind I'm thinking of). An adaptive filter, though,
might not, though it'd be time-invariant between adaptations.

A DSP / math-oriented guy would look at a mixer or modulator and say "See,
it's linear!" because the stage is a-times-b. Look, no second- or third-order
terms! An EE guy would say "it generates new frequencies, it's not linear."
The EE guy means "function of one variable that only changes the scale or
intercept".

Just terminology differences, is all it is.

Paul Burridge wrote:
What *is* "current steering"? Does it for example refer to direction
or level or both? And what does the steering?

I'm tempted to say that it's like power steering, but without voltage
steering. But I won't say that.

--
"Here, Outlook Express, run this program." "Okay, stranger."

Paul Burridge wrote:
What *is* "current steering"? Does it for example refer to direction
or level or both? And what does the steering?

I'm tempted to say that it's like power steering, but without voltage
steering. But I won't say that.

--
"Here, Outlook Express, run this program." "Okay, stranger."