How to matching PNP with NPN Transistor

senee · 26th February 2005, 08:10 AM

Hi,
Anyone to know, How to matching PNP with NPN Transistor?
I buy 2N5551= 20 ea. and 2N5401 = 20 ea. then hFE measure is more difference

hFE of 2N5551 = 110 to 130
hFE of 2N5401 = 210 to 230

I am making the power amplifier, when I put them in the circuit, It may be not good sound.

Have anyone suggestion?

sorry!!! My english is not good.

Senee

anatech · 26th February 2005, 09:40 PM

Hi Senee,
The best you can do, short of buying more transistors, is put the closest ones together. If these are for n and p diff pairs, match your pairs then use the closest n and p pairs. This will be better than most production amps so don't worry too much about it.
-Chris

senee · 27th February 2005, 04:52 AM

Thanks, Chris

AndrewT · 27th February 2005, 06:58 PM

Hi,
are you matching Hfe at 1 bias current?
Once you have sets that closely match try measuring the Vbe at a very low current(100uA to 1ma). Select for both Vbe and Hfe matching.

thanh · 27th February 2005, 11:53 PM

i think if you build a fully symmetry amp, you only need match npn ann npn, pnp and pnp .This topo has a very high capacity of cancel offset .I'm sorry! my english is not goog.Can you correct my sentence?

anatech · 28th February 2005, 12:12 AM

Hi thanh,
My experience shows that, in order of importance, the pairs must be matched (NPN to NPN, PNP to PNP). Then, each pair should be matched to the other. There is a difference if you include the last step.

If you match these at one current, say 1 mA (common test current), you are already ahead of the game. To complete a great job, thermally tie the pairs together. Now they track.

-Chris

DonoMan · 28th February 2005, 12:18 AM

You can choose different resistor values for each transistor to try to account for different gains. Though matching transistors is better.

K-amps · 28th February 2005, 06:08 PM

Quote:

Originally posted by DonoMan
You can choose different resistor values for each transistor to try to account for different gains. Though matching transistors is better.

Base resistors or emitters or both?

DonoMan · 28th February 2005, 07:22 PM

Just a base resistor should do it, but don't change the DC offset.

I THINK (and someone please correct me if I'm wrong) that if Q1 HFE = 100 and Q2 HFE = 200, then R2 = (200 / 100) * R1

anatech · 28th February 2005, 10:19 PM

I don't know about that. Why not just match them since you have measured them???

-Chris

26th February 2005, 08:10 AM	#1
senee diyAudio Member Join Date: Jun 2004 Location: Central in Thailand	How to matching PNP with NPN Transistor Hi, Anyone to know, How to matching PNP with NPN Transistor? I buy 2N5551= 20 ea. and 2N5401 = 20 ea. then hFE measure is more difference hFE of 2N5551 = 110 to 130 hFE of 2N5401 = 210 to 230 I am making the power amplifier, when I put them in the circuit, It may be not good sound. Have anyone suggestion? sorry!!! My english is not good. Senee __________________ Senee

27th February 2005, 04:52 AM	#3
senee diyAudio Member Join Date: Jun 2004 Location: Central in Thailand	Thanks, Chris __________________ Senee

27th February 2005, 06:58 PM	#4
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, are you matching Hfe at 1 bias current? Once you have sets that closely match try measuring the Vbe at a very low current(100uA to 1ma). Select for both Vbe and Hfe matching. __________________ regards Andrew T.

27th February 2005, 11:53 PM	#5
thanh diyAudio Member Join Date: Jan 2004 Location: ho chi minh city	i think if you build a fully symmetry amp, you only need match npn ann npn, pnp and pnp .This topo has a very high capacity of cancel offset .I'm sorry! my english is not goog.Can you correct my sentence? __________________ Justice for Victims of Agent Orange http://www.petitiononline.com/AOVN/Thank all of you!

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26th February 2005, 09:40 PM	#2
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi Senee, The best you can do, short of buying more transistors, is put the closest ones together. If these are for n and p diff pairs, match your pairs then use the closest n and p pairs. This will be better than most production amps so don't worry too much about it. -Chris

28th February 2005, 12:12 AM	#6
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi thanh, My experience shows that, in order of importance, the pairs must be matched (NPN to NPN, PNP to PNP). Then, each pair should be matched to the other. There is a difference if you include the last step. If you match these at one current, say 1 mA (common test current), you are already ahead of the game. To complete a great job, thermally tie the pairs together. Now they track. -Chris

28th February 2005, 12:18 AM	#7
DonoMan diyAudio Member Join Date: Feb 2005 Location: Massachusetts	You can choose different resistor values for each transistor to try to account for different gains. Though matching transistors is better.

28th February 2005, 07:22 PM	#9
DonoMan diyAudio Member Join Date: Feb 2005 Location: Massachusetts	Just a base resistor should do it, but don't change the DC offset. I THINK (and someone please correct me if I'm wrong) that if Q1 HFE = 100 and Q2 HFE = 200, then R2 = (200 / 100) * R1

28th February 2005, 10:19 PM	#10
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	I don't know about that. Why not just match them since you have measured them??? -Chris

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