Sure, and that helps the tracking a lot, but it also loses the advantage in output swing that Tim was talking about.
Cheers
Phil Hobbs
Sure, and that helps the tracking a lot, but it also loses the advantage in output swing that Tim was talking about.
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 hobbs at electrooptical dot net http://electrooptical.net
it depends on the axis you use to flip it.
rotate 180 degrees about the line from pin 1 centre through the centre between pins 2 and 3,
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Because they're bigger devices, silly. The BCV62 has a specified theta_JA of 500 K/W. Given a theta number, it's really easy to calculate the thermal stability limit analytically.
Nah, I use them a fair amount, but only down below 500 uA. They're also useful for making temperature compensated current sources, for instance--think of the diode-connected device as a way of temperature compensating the V_BE of the current source device.
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 hobbs at electrooptical dot net http://electrooptical.net
It would have to be upside down and rotated. It actually does fit well enough that you don't need bits of wire -- but on the parts we had you couldn't reform the leads without them breaking off, so it's a highly questionable thing to do with a production board. We just did it to verify the rest of the board before giving the layout a hard time and doing it over.
Your adapter board idea is probably better, if they fit, or your rotate- and-wire idea. It's a hell of a lot of work, though.
-- Tim Wescott Wescott Design Services http://www.wescottdesign.com
Try it some time... in CMOS it can actually _improve_ the swing range before the current decreases (patent pending :) ...Jim Thompson
-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 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 don't read that set of curves (strange as they are) as implying run-away. When I have a moment I'll run some numbers. ...Jim Thompson
-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 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 determined that the transistor wasn't needed, it was overkill, so suck off transistor, replace with a resistor... lots of labor but, fortunately, it's on main-land China. ...Jim Thompson
-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 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.
'Tain't hard to calculate. At constant V_BE, a junction temperature rise of 1 degree produces a current increase of 9%. Assuming a low-Z collector load, device dissipation increases by 9% as well. Instability will occur if that 9% causes a temperature change of another degree, i.e.
0.09 I_C V_CE theta_JA > 1 K.The general derivation isn't much harder, even with a more complicated load.
If you bias the output transistor near its maximum-power point, you can even use this effect as a temperature controller:
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 hobbs at electrooptical dot net http://electrooptical.net
"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...
Sure, but BSS84s are 4c/ea in 1000s, versus MMBT3906s for 2.2c. And they probably aren't as well matched. Actually, I haven't compared FETs on tape... hmm...
Tim
-- Seven Transistor Labs Electrical Engineering Consultation Website: http://seventransistorlabs.com
Yup -- still fine when a wimp is all you need. And in the grander scheme of things, 0.5mA is hardly useless.
Any clue how the Rth(j-j) is between them? Twin packs are notoriously weak, but I wonder if having common metal makes them any better, even if it's two bond wires.
Tim
-- Seven Transistor Labs Electrical Engineering Consultation Website: http://seventransistorlabs.com
OK, for that you need to charge a fee.
$0.xx for chalking a mark on a pipe. $XXX,XXX.xx for knowing where to make a chalk mark on a pipe...
-- Tim Wescott Wescott Design Services http://www.wescottdesign.com
I have some germanium transistors which act like really slow latches. Once turned on, they bias themselves at half supply voltage, go figure!
Tim
-- Seven Transistor Labs Electrical Engineering Consultation Website: http://seventransistorlabs.com
GE built some radios and phono amps with crap like that in the '60. No bias resistors, just the internal leakage. Probably fallout from the military & commercial product lines.
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In the classic low-level audio amp stage bias scheme (divider to bias up the base, resistor in the source) the base divider often took current *out* of the base!
One occasionally saw an amp circuit with the base of a Ge transistor driven through a cap... and nothing else.
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The Infineon ones seem to be a bit better--they claim somewhat higher maximum dissipation before instability.
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 hobbs at electrooptical dot net http://electrooptical.net
The synchronized-runaway trick can be used to enable multiple transistor array chips to be used much like a single larger array. That's potentially quite useful in my business.
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 hobbs at electrooptical dot net http://electrooptical.net
I believe that. CMOS tends to be crappy that way, but OTOH you can bandage it with a whole lot of auxiliary transistors.
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 hobbs at electrooptical dot net http://electrooptical.net
Theta_JA isn't the pertinent number, it's Theta_JC (junction to case), or even more accurately junction-to-mounting-slug. What did you get you PhD in... exaggeration ?>:-}
More in a couple of days... off to Yuma to the inauguration of the son-in-law. ...Jim Thompson
-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 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.
Yep, that's the (golden) rule >:-} ...Jim Thompson
-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 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.
The best of all worlds is BiCMOS. But CMOS isn't "crappy"... if you know how to design with it. With my proprietary cascode I can easily get to 0.2V of rail before it sags. ...Jim Thompson
-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 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.
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