Author Topic: Matched transistors for analog experiments  (Read 70475 times)

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Offline RoGeorgeTopic starter

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Matched transistors for analog experiments
« on: February 13, 2024, 09:04:10 pm »
Looking for factory matched BJT transistors, but I wouldn't mind finding some matched JFET or MOSFET either.  They are for experimenting with long tails, current mirrors and alike.  This is hobby level, so I don't want to break the bank buying $30/1pair of famous NOS part numbers.

I've looked at mouser, and for 'transistors array' it returns all kind of darlington and drivers and H bridges.  When searching for 'matched transistors' there are only 3 part numbers, decent price (less than $0.5-$1/pcs), but they are all pnp pairs.

There are some ROHM pairs from their THAT300 series, advertised in a mouser "what's new" page, but they do not appear as products for sale, only advertised and no link to buy.

The matched transistors are for casual learning and experimenting with discrete analog IC-like structures.  Required specs are as good as possible, but at very low cost, less than $1/pair.

- What paired transistors part numbers to look for, and what search term to use?
- Will factory matched be better matched than hand-matching from a casual bag of 20..50 THT discrete transistors of the same type?
« Last Edit: February 13, 2024, 09:07:46 pm by RoGeorge »
 

Offline Andy Watson

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Re: Matched transistors for analog experiments
« Reply #1 on: February 13, 2024, 09:18:43 pm »
- What paired transistors part numbers to look for, and what search term to use?
Try "dual transistor"

In my limited experience, you will struggle to match individual transistors to the same level that is easily and readily obtained with transistors that are on the same die. I believe CA3046 are still available.
 
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Offline Kleinstein

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Re: Matched transistors for analog experiments
« Reply #2 on: February 13, 2024, 09:24:05 pm »
There are a few cheap dual BJTs (e.g. SOT23-6). They offer some degree of matching, though not as good as the higher cost SSM2212 or THAT300.
Examples are FMBM5551, NST45011.
THT duals are rare however and can get expensive.

For JFETs there is the SK2145 as the prime candidate for a cheap pair - though already connected source to source.  There are also some more dual JFETs, but not all offer good matching, at least not guaranteed.
For high performance the JFE2140 is a candidate to look at, though more in the $4 range, still not super expensive.

Chances are manual matching could be more accurate (at least for the parameters tested), if one starts with transistors that are quite uniform or accepts a low yield (e.g. only use the best 1 or 2 pairs out of 20).
 
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Offline magic

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Re: Matched transistors for analog experiments
« Reply #3 on: February 13, 2024, 09:36:43 pm »
Required specs are as good as possible, but at very low cost, less than $1/pair.
This virtually rules out monolithic pairs, unless you manage to find some obsolete transistor arrays on eBay or similar sites. I think I have seen a 5-NPN array for $2 once. You can probably forget PNP.

If you look at dual transistors in SOT23-6, some of them are offered with ±2mV offset guarantee. IIRC suppliers were NXP and Diodes and part numbers were quite generic: xxx847xx, xxx3404xxx, xxx5551xxx or their PNP analogs. I imagine these may be very handy for mass production.

The Vbe spread in a bag of 2N3904/3906 or BC847/857 from decent manufacturers like Fairchild (now ON semi, I suppose) is very small, a few mV. You will easily harvest multiple pairs with 2mV or even 1mV offset. Test with DMM diode mode, one probe on E and one on BC shorted together. Or get the AVR transistor tester, which will also show β.


I hope you know that 2mV matching only holds if internal junction temperatures stay within 1°C of each other. Only realistic if power dissipation is very low or equalized.
 
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Offline djsb

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Re: Matched transistors for analog experiments
« Reply #4 on: February 13, 2024, 09:38:27 pm »
Alfa in latvia still make a LM194/394 equivalent. They are discussed in this thread

https://www.diyaudio.com/community/threads/lm194-lm394.333623/

They can be bought from Erica synths or Thonk in the UK.
David
Hertfordshire, UK
University Electronics Technician, London, PIC16/18, CCS PCM C, Arduino UNO, NANO,ESP32, KiCad V8+, Altium Designer 21.4.1, Alibre Design Expert 28 & FreeCAD beginner. LPKF S103,S62 PCB router Operator, Electronics instructor. Credited KiCad French to English translator
 

Offline exe

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Re: Matched transistors for analog experiments
« Reply #5 on: February 13, 2024, 09:39:31 pm »
For bjt: try BCM846 and other BCM* parts.
 

Offline moffy

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Re: Matched transistors for analog experiments
« Reply #6 on: February 13, 2024, 09:46:44 pm »
Got this result at Mouser using the term "matched transistor": https://au.mouser.com/c/?q=matched%20transistor&sort=pricing
Surprisingly good matching for low cost pairs, 2mv Vbe and 2% hfe.
 

Offline PCB.Wiz

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Re: Matched transistors for analog experiments
« Reply #7 on: February 13, 2024, 11:57:14 pm »
Looking for factory matched BJT transistors, but I wouldn't mind finding some matched JFET or MOSFET either. 
....
- What paired transistors part numbers to look for, and what search term to use?

As above in #6, use matched.  They can be as good as 2mV and 2%.  TI have a new matched pair JFET.

Here are some from my local drive - note you can also get 40V / 6A parts matched.

JFE2140_TI_JFET_Dual_40V_0p9nV_4mV_Match_1d64
NSS40300MD-D_DualPNP_Match_40V_6A_SO8_HFEt230_2A
NSS40301MD-D_DualNPN_Match_40V_6A_SO8_HFEt320_2A
2304140030_Nexperia-PMP5201Y-115_C553005_MatchPNP_45V_2mV_2pc_SOT363
1810261910_Diodes-Incorporated-DMMT5401-7-F_C154733_MatchedPNP_150V_2pc_SOT26
bcm847bs_diotec_Dual_Match_2mV10pc_SOT363
PMP4201V_DualNPN_Matched_2pc2mV

- Will factory matched be better matched than hand-matching from a casual bag of 20..50 THT discrete transistors of the same type?
I would expect a lot better, than a bag-match.
It will take you a while to find 2% HFE and 2% VBE matches.

Parts from 'the same reel' can be expected to be somewhat matched. I think Infineon had an appnote on the spreads.


 
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Offline David Hess

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Re: Matched transistors for analog experiments
« Reply #8 on: February 14, 2024, 02:25:52 am »
Texas Instruments makes a monolithic matched JFET based on their more recent high voltage JFET process available as the JFE214:

https://www.mouser.com/ProductDetail/Texas-Instruments/JFE2140DR?qs=A6eO%252BMLsxmQVeRIGZCabaw%3D%3D

Digikey and Mouser now sell matched MOSFETs and JFETs from Linear Systems, but apparently not their bipolar transistors.  These are the real thing:

https://www.mouser.com/c/?m=Linear%20Integrated%20Systems

Calogic makes matched transistors but they are not as easily available.

If you buy 10, 25, or 100 transistors in bulk, then you can match them pretty well yourself with some test circuits.  This will be good enough for hobby and student work.  Glue pairs together for temperature tracking.
 
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Offline moffy

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Re: Matched transistors for analog experiments
« Reply #9 on: February 14, 2024, 02:52:02 am »

JFE2140_TI_JFET_Dual_40V_0p9nV_4mV_Match_1d64


The JFE2140, a dual matched low noise JFET, available and a reasonable price, nice. :)
 

Offline mawyatt

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Re: Matched transistors for analog experiments
« Reply #10 on: February 14, 2024, 03:08:56 am »

If you buy 10, 25, or 100 transistors in bulk, then you can match them pretty well yourself with some test circuits.  This will be good enough for hobby and student work.  Glue pairs together for temperature tracking.


Remember way back when there were small metal clips that held 2 TO92 transistors face to face to create a "Matched Pair" from select devices. One could use a "C" chip made from heavy gauge bare wire also, or as you indicate just Super Glue them together.

Best,
Curiosity killed the cat, also depleted my wallet!
~Wyatt Labs by Mike~
 

Offline Jeff eelcr

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Re: Matched transistors for analog experiments
« Reply #11 on: February 14, 2024, 02:18:19 pm »
Japanise transistors are labeled with gain group if all numbers on the parts are the same from the same manufacturer
they are matched parts.
Can not say the same for US or Euro parts.
Jeff
 

Online Zero999

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Re: Matched transistors for analog experiments
« Reply #12 on: February 14, 2024, 02:43:47 pm »
NPN or PNP?

I've seen the PNP, DMMT5401 used in ideal diode circuits, but the data sheet doesn't specify matching. Presumably it's pretty good. The NPN version is DMMT5551.
 

Offline RoGeorgeTopic starter

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Re: Matched transistors for analog experiments
« Reply #13 on: February 14, 2024, 03:27:34 pm »
Both types.


Also, thank you all for suggestions.


Offline Kleinstein

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Re: Matched transistors for analog experiments
« Reply #14 on: February 14, 2024, 05:06:21 pm »
Japanise transistors are labeled with gain group if all numbers on the parts are the same from the same manufacturer
they are matched parts.
Can not say the same for US or Euro parts.
Jeff
For the gain groups it depends. One can get some type in gain groups or without.  The naming can be different depending on the types : E.g. with an extra number like  -10, -16,-25, -40  for the BD135 or BC337 or a letter like BC547A,B,C or with Japanese sometimes color dots, sometimes written as a letter on the bag (e.g. O,G,Bl) or when ordering.

The matching in the gain (or threshold with FETs) is often not that tight. One may want more than that in some applications.
It also depends on the application what parameter should be matched (e.g. VBE, hfe, Vsat, Vearly) though to a large part the parameters are quite correlated for parts from the same batch.


Even if the dual parts don't specify matching, it often is quite good, but may want a check.
 

Offline magic

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Re: Matched transistors for analog experiments
« Reply #15 on: February 14, 2024, 05:19:18 pm »
I pulled 5 completely random CDIL 2N2222A from my parts box and tested them for Vbe and hFE on a DMM.
That's one of the cheapest TO92 transistors in the world from a cheap Indian manufacturer, they cost pennies at TME.

Vbe: all five were 649~651mV
hFE: four were 160~165, one was 167

IMO thermal matching (including during selection) is more likely to be an issue in practice than production variation.
 
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Offline mawyatt

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Re: Matched transistors for analog experiments
« Reply #16 on: February 14, 2024, 06:24:55 pm »
Looking for factory matched BJT transistors, but I wouldn't mind finding some matched JFET or MOSFET either.  They are for experimenting with long tails, current mirrors and alike.  This is hobby level, so I don't want to break the bank buying $30/1pair of famous NOS part numbers.

I've looked at mouser, and for 'transistors array' it returns all kind of darlington and drivers and H bridges.  When searching for 'matched transistors' there are only 3 part numbers, decent price (less than $0.5-$1/pcs), but they are all pnp pairs.

There are some ROHM pairs from their THAT300 series, advertised in a mouser "what's new" page, but they do not appear as products for sale, only advertised and no link to buy.

The matched transistors are for casual learning and experimenting with discrete analog IC-like structures.  Required specs are as good as possible, but at very low cost, less than $1/pair.

- What paired transistors part numbers to look for, and what search term to use?
- Will factory matched be better matched than hand-matching from a casual bag of 20..50 THT discrete transistors of the same type?

Since this is a learning experience doesn't this give you an excuse necessity requirement for a curve tracer ;)

Maybe use the technique you posted about controlling your PS for the Curve Tracer :-+

Or better yet, an excuse necessity requirement for a pair of SMUs ;D

Best,
« Last Edit: February 14, 2024, 06:27:08 pm by mawyatt »
Curiosity killed the cat, also depleted my wallet!
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Offline HalFoster

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Re: Matched transistors for analog experiments
« Reply #17 on: February 14, 2024, 06:51:36 pm »
I use AD's MAT02 quite often and have always had very good results.

Hal
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Offline David Hess

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Re: Matched transistors for analog experiments
« Reply #18 on: February 15, 2024, 12:24:54 am »
I use AD's MAT02 quite often and have always had very good results.

The Analog Devices' MAT series are great, except for the price, and the PNP parts seem to be missing.

It also depends on the application what parameter should be matched (e.g. VBE, hfe, Vsat, Vearly) though to a large part the parameters are quite correlated for parts from the same batch.

That is my experience.  Within the same lot of the same part, matching for one parameter largely matches for the others.
 

Offline twospoons

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Re: Matched transistors for analog experiments
« Reply #19 on: February 15, 2024, 03:59:52 am »
Don't bother hand matching individual parts, its a waste of time. The two devices need to be thermally matched as well - so at very least inside one package, preferably on the same die.
 

Online Zero999

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Re: Matched transistors for analog experiments
« Reply #20 on: February 19, 2024, 08:53:53 am »
I thought I'd post a link to a thread offering some LM394s for free, in case the original poster hasn't seen it.
https://www.eevblog.com/forum/projects/lm394s-free-to-a-good-home/
 
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Offline kimballa

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Re: Matched transistors for analog experiments
« Reply #21 on: February 20, 2024, 04:40:05 pm »
BCM847 for NPN, BCM857 for PNP are basically the only game in town I've found that's reliably stocked, guaranteed matching specs (delta-Vbe < 2mV), and available at about $0.50 per pair.

Both are SOT-23-6. I've used them successfully in DIY audio synth applications.
 
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Offline kimballa

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Re: Matched transistors for analog experiments
« Reply #22 on: February 20, 2024, 04:41:05 pm »
PS make sure you get the BCM - M for matching. There's a separate unmatched NPN called BC847. Not the same.
 
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Offline prosper

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Re: Matched transistors for analog experiments
« Reply #23 on: February 21, 2024, 02:55:46 am »
i have a curve tracer. hand matching transistors out of a bag isn't all that time consuming. i wonder how easily a curve tracer could be be constructed today with modern parts - you don't even need all the bells and whistles, or even a display; set it up to run a handful of measurements near your expected operating point on two parts at once, and light a led iif they're close enough. might be an interesting project
 

Offline PCB.Wiz

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Re: Matched transistors for analog experiments
« Reply #24 on: February 21, 2024, 05:05:53 am »
BCM847 for NPN, BCM857 for PNP are basically the only game in town I've found that's reliably stocked, guaranteed matching specs (delta-Vbe < 2mV), and available at about $0.50 per pair.

Both are SOT-23-6. I've used them successfully in DIY audio synth applications.

BCM8xx are 5% HFE matching, you can also get tighter HFE matching to 2% HFE and 2mV

https://www.nexperia.com/products/bipolar-transistors/special-feature-transistors/matched-pair-transistors#/p=1,s=0,f=cf9523:0.98;0.98,c=,rpp=,fs=0,sc=,so=,es=
 
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