That makes no sense at all.
-- 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
Jim
tce.
I plunked a PNP (in CCS configuration) in instead of the bootstrap cap--it almost drops right in--but I haven't matched your gain figures.
For silliness I then a.c. bootstrapped your current source by putting the boost cap back. Very silly!
-- Cheers, James Arthur
On Wed, 16 Jan 2013 17:11:31 -0800 (PST), snipped-for-privacy@yahoo.com wrote:
The PNP follower bootstraps its own b-e resistor. That lets the NPN run at a relatively high current (high Gm) but see a high impedance collector load, which gets you lots of voltage gain.
Version 4 SHEET 1 880 772 WIRE 400 -112 0 -112 WIRE 400 -80 400 -112 WIRE 0 64 0 -112 WIRE 400 64 400 0 WIRE 400 64 208 64 WIRE 208 160 208 64 WIRE 0 176 0 144 WIRE 400 176 400 64 WIRE 528 176 400 176 WIRE 608 176 528 176 WIRE 672 176 608 176 WIRE 400 240 400 176 WIRE 208 288 208 240 WIRE 336 288 208 288 WIRE 208 368 208 288 WIRE 400 400 400 336 WIRE 528 400 528 176 WIRE -224 416 -304 416 WIRE -160 416 -224 416 WIRE -16 416 -96 416 WIRE 144 416 -16 416 WIRE -304 464 -304 416 WIRE 208 512 208 464 WIRE -16 576 -16 416 WIRE 400 576 -16 576 WIRE 528 576 528 480 WIRE 528 576 400 576 WIRE -304 592 -304 544 WIRE 400 624 400 576 WIRE 400 752 400 704 FLAG 208 512 0 FLAG 400 752 0 FLAG 0 176 0 FLAG -304 592 0 FLAG 608 176 OUT FLAG -224 416 GEN FLAG 400 400 0 SYMBOL res 192 144 R0 WINDOW 0 -60 34 Left 2 WINDOW 3 -63 72 Left 2 SYMATTR InstName R2 SYMATTR Value 5K SYMBOL res 512 384 R0 WINDOW 0 70 38 Left 2 WINDOW 3 60 73 Left 2 SYMATTR InstName R3 SYMATTR Value 220K SYMBOL res 384 608 R0 WINDOW 0 -72 29 Left 2 WINDOW 3 -83 64 Left 2 SYMATTR InstName R4 SYMATTR Value 220K SYMBOL npn 144 368 R0 WINDOW 0 98 24 Left 2 WINDOW 3 74 56 Left 2 SYMATTR InstName Q1 SYMATTR Value 2N5089 SYMBOL cap -96 400 R90 WINDOW 0 -18 31 VBottom 2 WINDOW 3 45 31 VTop 2 SYMATTR InstName C2 SYMATTR Value 10µ SYMBOL voltage 0 48 R0 WINDOW 0 -107 13 Left 2 WINDOW 3 -111 51 Left 2 SYMATTR InstName V1 SYMATTR Value 3.3 SYMBOL voltage -304 448 R0 WINDOW 123 24 124 Left 2 WINDOW 39 24 152 Left 2 SYMATTR Value2 AC 0.01 SYMATTR SpiceLine Rser=1K SYMATTR InstName V2 SYMATTR Value SINE(0 0.001 1K) SYMBOL pnp 336 336 M180 SYMATTR InstName Q2 SYMATTR Value 2N4403 SYMBOL res 384 -96 R0 WINDOW 0 73 42 Left 2 WINDOW 3 71 76 Left 2 SYMATTR InstName R1 SYMATTR Value 5K TEXT -272 248 Left 2 !;tran 0.01 TEXT -336 200 Left 2 !.ac oct 10 10 1meg
-- 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
Most of what I use bootstrapping for is to reduce the effect of capacitance on high sensitivity front ends. You can get bandwidth improvements of tens to hundreds of times by doing bootstrapping right. It isn't a free lunch, of course--it doesn't improve the SNR, just the frequency response.
All the other characteristics through bootstrapping, of the
A good bootstrap can also improve linearity out of all recognition. With a gain of 0.995 or higher, there isn't much opportunity for the gain to vary with signal.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 USA +1 845 480 2058 hobbs at electrooptical dot net http://electrooptical.net
performance.
Yes, I know, but the PNP's action is imperfect. So, in silly-land, I used the cap bootstrapping trick to feed _your_ CCS from a cap- bootstrapped CCS. :-)
Cute. I was going to gripe about the output impedance, but it's really pretty good.
Using magic SPICE transistors you can change the bias resistors from
220k to 1M, which boosts the gain even more. I wouldn't dare IRL, natch.-- Cheers, James Arthur
performance.
Hmmm... it shouldn't be, unless the generator impedance is high enough to let some feedback work, and then the gain goes down. Free lunch and all that.
BCX70K has a min beta of 380. 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
Ya know what, i may simulate it to see if it is as bad as you say. It certainly seems to have problems from what i have posted already.
?-)
...Jim
got
Cool, what is the part number? Just the same i would like to experiment (play) with a few if you are feeling generous this week.
?-)
E-mail me a physical address. ...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.
I've sim'd James' version and my PNP spin. With bigger caps, they make nice audio-range amps with tons of gain. JT doesn't like it because he doesn't understand 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
o.com
's
let
The 2n5089 has min beta of 450 @ 1mA. Lovely part. I like the BCX70K too.
At ic=60uA, beta = 400, we'll need ib=150nA across [500k bias network z] = 75mV. Okay, I guess that's not a big deal. Wheeee!
-- Cheers, James Arthur
snipped-for-privacy@yahoo.com
We geeks are easily amused.
-- 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
nice
doesn't
Not realistic. JT understands it better than you ever will/could. Your narcissism is outshining everything else about you again.
?-)
Yep. I understand it... and Larkin is indeed a narcissistic village idiot.
I did try it myself with larger caps, which flattens the bandpass somewhat.
The real snag, that catches idiots like Larkin, is the capacitor straight into the base. Unless you have a high source impedance, it's crap.
I wonder if Larkin would care to treat us to a mathematical analysis?
I doubt that he can.
He'd rather hand-wave his simulation results... which he is too dumb to understand >:-} ...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.
He admitted that he didn't understand it, and said a couple of truly stupid things. That's shocking, given how simple it is.
I liked it and I think that I both simplified and improved it, with the PNP thing; that happens when people play with circuits instead of whining about them. This one ain't rocket science, but it's cute and educational.
You and Jim have, so far, just grumped about how you don't like it, and said things that, while fuzzy and qualitative, aren't true.
Quit whining and design something. Try to be constructive once in a while; you'll feel better.
-- 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
You still don't get it. You keep thinking it's an opamp and the input should be a summing point. The high gain, which James wants, happens when the generator impedance is *low*, and the feedback is just to get the dc bias right.
Good grief, it's simple. The dc current of the NPN is clearly controlled. That gives Gm directly, and voltage gain is ideally Gm * Zl where Zl is what its collector sees. Without the bootstrapping, Zl is dominated by the collector resistor, which is DC constrained, so gain is low, as in the classic "voltage gain is 40 times the DC drop in the collector resistor" which falls out of basic transistor theory. With a 3.3 volt supply, voltage gain must be low. Bootstrapping breaks that constraint, increasing the gain 20 dB or so (more in my PNP version.) Bootstrapped gain depends on the follower's gain and the Early slope of the NPN.
Given a goal and an understanding of the mechanisms and a ballpark feel for the numbers, one may as well then simulate, especially if the transistor models are already there in Spice. That does the full gain-frequency thing in seconds, which sure beats spending the afternoon using a slide rule or an abacus or whatever you use.
You have said nothing useful so far. All you do any more is boast and whine, or maybe wine. You are too fragile or too drunk to play with circuits.
-- 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
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.
The "bootstrap" provides a low-pass effect, thus the overall behavior of the original imperfect structure is a low-Q band-pass.
Capacitive input until the "bootstrap" cuts in, then flops negative into equivalent inductance :-(
I can provide an exact mathematical analysis, should anyone want to see it. But I doubt that Larkin and sycophants could understand it
...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.
Any AC coupled amp is a differentiator.
Any audio amp is a low-Q bandpass filter. Quit being a pompous ass.
That's not at all uncommon, but I guess it's new to you.
The amp works.
-- 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
Well- you don't use that kind of feedback with that kind of source unless you use a series input resistor for voltage to current conversion.
use a series input resistor for voltage to current conversion.
The feedback is just to set the DC bias point. It's an open-loop amp at frequencies of interest, and James wants lots of gain. You and Jim refuse to accept that intent.
-- 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
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