Reply by John Larkin January 30, 20132013-01-30
On Tue, 29 Jan 2013 18:57:45 -0800, josephkk <joseph_barrett@sbcglobal.net>
wrote:

>On Mon, 28 Jan 2013 18:13:54 -0500, rickman <gnuarm@gmail.com> wrote: > >>On 1/27/2013 8:30 PM, John Larkin wrote: >>> On Sun, 27 Jan 2013 19:33:05 -0500, rickman<gnuarm@gmail.com> wrote: >>>> >>>> I see why you have so much trouble with so many people here. >>> >>> Trouble? I hadn't noticed. >> >>Exactly! >> >>Rick > >JL is so narcissistic that he thinks that anyone that responds to him is >praising him. > >?-)
Obviously not. I just appreciate that in an unmoderated forum, there will be all sorts of people. I tend to get along with people who are helpful and serious about electronics, and the rest don't matter. Public forums attract idiots and old hens. This one is no different. That doesn't make "trouble" for me. If rickman, or you, want to join the my-o-my chickencoop, go for it. -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
Reply by josephkk January 29, 20132013-01-29
On Mon, 28 Jan 2013 18:13:54 -0500, rickman <gnuarm@gmail.com> wrote:

>On 1/27/2013 8:30 PM, John Larkin wrote: >> On Sun, 27 Jan 2013 19:33:05 -0500, rickman<gnuarm@gmail.com> wrote: >>> >>> I see why you have so much trouble with so many people here. >> >> Trouble? I hadn't noticed. > >Exactly! > >Rick
JL is so narcissistic that he thinks that anyone that responds to him is praising him. ?-)
Reply by John Larkin January 28, 20132013-01-28
On Mon, 28 Jan 2013 18:13:54 -0500, rickman <gnuarm@gmail.com> wrote:

>On 1/27/2013 8:30 PM, John Larkin wrote: >> On Sun, 27 Jan 2013 19:33:05 -0500, rickman<gnuarm@gmail.com> wrote: >>> >>> I see why you have so much trouble with so many people here. >> >> Trouble? I hadn't noticed. > >Exactly! > >Rick
If you think I have "so much trouble", and I don't, it seems like your problem. -- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
Reply by rickman January 28, 20132013-01-28
On 1/27/2013 8:30 PM, John Larkin wrote:
> On Sun, 27 Jan 2013 19:33:05 -0500, rickman<gnuarm@gmail.com> wrote: >> >> I see why you have so much trouble with so many people here. > > Trouble? I hadn't noticed.
Exactly! Rick
Reply by John Larkin January 27, 20132013-01-27
On Sun, 27 Jan 2013 19:33:05 -0500, rickman <gnuarm@gmail.com> wrote:

>On 1/26/2013 6:07 PM, John Larkin wrote: >> On Sat, 26 Jan 2013 17:59:43 -0500, rickman<gnuarm@gmail.com> wrote: >> >>> On 1/24/2013 5:58 PM, John Larkin wrote: >>>> >>>> In real life, there is no such thing as a true differentiator. The >>>> circuit that James posted is AC coupled, and JT (and not I) called it >>>> a differentiator... just above. >>>> >>>> My point was that all AC coupled amps behave sort of like >>>> differentiators. James' circuit is no different. >>> >>> Ok, I'll bite, why is there no such thing as a "true" differentiator? >>> The op-amp circuit above is a pretty good example of a "true" >>> differentiator in my opinion. >> >> A true diff would need infinite bandwidth. >> >>> >>> I was referring to *your* comment that "Any AC coupled amp is a >>> differentiator". That is not correct, period. >> >> It is by Jim's standards for a differentiator. > >So all of your statements are wrong. A differentiator is a >differentiator even if it is not "perfect" with ideal components. > >AC coupled amps are not "sort of like differentiators". They are like >low pass filters.
Unless they are DC coupled, they behave like bandpass filters. On their low-frequency skirt, they sort of differentiate. As a single-pole RC highpass filter sort of differentiates. But you are arguing definitions, words. Circuits do what they do and don't care what you call them. If a circuit differentiates well enough for you, call it a differentiator. If the output is K * dV/dT over all bandwidths and amplitudes, it's a true differentiator. There are none. The only way to consider them differentiators is in
>the limit as your signal amplitude diminishes to zero.
Zero amplitude? For a linear transfer function? In that case
>your circuit is also not doing anything useful "in the limit". > >I see why you have so much trouble with so many people here.
Trouble? I hadn't noticed. -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
Reply by rickman January 27, 20132013-01-27
On 1/26/2013 6:07 PM, John Larkin wrote:
> On Sat, 26 Jan 2013 17:59:43 -0500, rickman<gnuarm@gmail.com> wrote: > >> On 1/24/2013 5:58 PM, John Larkin wrote: >>> >>> In real life, there is no such thing as a true differentiator. The >>> circuit that James posted is AC coupled, and JT (and not I) called it >>> a differentiator... just above. >>> >>> My point was that all AC coupled amps behave sort of like >>> differentiators. James' circuit is no different. >> >> Ok, I'll bite, why is there no such thing as a "true" differentiator? >> The op-amp circuit above is a pretty good example of a "true" >> differentiator in my opinion. > > A true diff would need infinite bandwidth. > >> >> I was referring to *your* comment that "Any AC coupled amp is a >> differentiator". That is not correct, period. > > It is by Jim's standards for a differentiator.
So all of your statements are wrong. A differentiator is a differentiator even if it is not "perfect" with ideal components. AC coupled amps are not "sort of like differentiators". They are like low pass filters. The only way to consider them differentiators is in the limit as your signal amplitude diminishes to zero. In that case your circuit is also not doing anything useful "in the limit". I see why you have so much trouble with so many people here. Rick
Reply by Jim Thompson January 27, 20132013-01-27
Now that I've established that the "Cute amplifier" signal equivalent
is a capacitor to ground paralleled by a current source, why is it
desirable that the bootstrap is inductive?

Start by pondering a conventional TIA and the stability issues with a
capacitive source, such as a photodiode.

First read this paper...

   http://eprints.lancs.ac.uk/20372/1/20372.pdf

Then note that the first stage gain of the "Cute amplifier" is...

   gm&#2013266069;(R1&#2013266069;R2&#2013266069;C1&#2013266069;s + R1 + R2)

What benefit does that provide?
		
                                        ...Jim Thompson
-- 
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.
Reply by Jim Thompson January 26, 20132013-01-26
The Leach paper (Figure 3)...

  http://users.ece.gatech.edu/~mleach/papers/spice_electro.pdf

Has no component values on it, but it's clearly a current source in
parallel with a capacitor.

Then I remembered a hearing aid design I did in 2004, so here's a
model with values you can use...

  http://www.analog-innovations.com/SED/CapacitiveMicrophoneModel.pdf
		
                                        ...Jim Thompson
-- 
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.
Reply by John Larkin January 26, 20132013-01-26
On Sat, 26 Jan 2013 17:59:43 -0500, rickman <gnuarm@gmail.com> wrote:

>On 1/24/2013 5:58 PM, John Larkin wrote: >> On Wed, 23 Jan 2013 18:13:27 -0500, rickman<gnuarm@gmail.com> wrote: >> >>> On 1/19/2013 1:50 PM, John Larkin wrote: >>>> On Sat, 19 Jan 2013 11:33:52 -0700, Jim Thompson >>>> <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: >>>> >>>>> >>>>> The "Cute amplifier - bootstrapped" as originally posted... >>>>> >>>>> +3.3V >>>>> --- >>>>> | >>>>> .-------+-------. >>>>> | | >>>>> 5K R1 C1 |/ Q2 >>>>> | 100n .------| 2n5089 >>>>> +---||-|--. |>. >>>>> | | | | >>>>> 15k R2 | '-----+------> >>>>> | | | >>>>> C2 +------' R3 820R >>>>> 10n |/ Q1 | >>>>> >--||-+--| 2n5089 .------+ >>>>> | |>. | | >>>>> | | | R4 470R >>>>> | === | | >>>>> | | === >>>>> '-----R5------' >>>>> 220k >>>>> >>>>> To make it understandable by Larkin and his sycophants, lets assume >>>>> that everything is perfection and light between the base of Q1 and the >>>>> emitter of Q2, in other words a perfect amplifier with infinite >>>>> gain... of course created by that phantabulous BOOTSTRAP>:-} >>>>> >>>>> So the circuit can be simplified to (pardon my ASCII :)... >>>>> >>>>> |\ >>>>> +-------|+\ >>>>> === | \ >>>>> | /------+------> >>>>> +-------|-/ | >>>>> | |/ | >>>>> C2 | R3 820R >>>>> 10n | | >>>>> >--||-+--+ .------+ >>>>> | | | >>>>> | | R4 470R >>>>> | | | >>>>> | | === >>>>> '-----R5------' >>>>> 220k >>>>> >>>>> Which any sycophant should be able to recognize as a differentiator. >>>> >>>> Any AC coupled amp is a differentiator. >>> >>> That's not true. A high pass filter is not the same as a >>> differentiator. Even I know that. They may be approximately the same >>> in a limit condition, but they won't behave the same in a real circuit. >>> >>> Rick >> >> In real life, there is no such thing as a true differentiator. The >> circuit that James posted is AC coupled, and JT (and not I) called it >> a differentiator... just above. >> >> My point was that all AC coupled amps behave sort of like >> differentiators. James' circuit is no different. > >Ok, I'll bite, why is there no such thing as a "true" differentiator? >The op-amp circuit above is a pretty good example of a "true" >differentiator in my opinion.
A true diff would need infinite bandwidth.
> > I was referring to *your* comment that "Any AC coupled amp is a >differentiator". That is not correct, period.
It is by Jim's standards for a differentiator. -- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
Reply by John Larkin January 26, 20132013-01-26
On Sat, 26 Jan 2013 18:03:11 -0500, rickman <gnuarm@gmail.com> wrote:

>On 1/21/2013 8:15 PM, Jim Thompson wrote: >> >> That's stupid. >> >> You're being Larkinesque evasive (and obfuscative... have you been >> taking lessons ?:-) >> >> Write the equations. Already! >> >> Tick-tock. >> >> You're going down. It always happens to sycophants, you take the >> fall, Larkin walks away>:-} >> >> ...Jim Thompson > >My dear GOD! You guys are all what, 12 years old??? > >I bet you and Larkin get together at night and watch SuperTroopers! > >"Bite it, rook!" > >Rick
Jim is 107, I think. -- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation