Low noise transistor and noise figure

[Real_Macgyver]

Low noise transistor and noise figur

Any suggestions for SMD input transistors with very low noise?

Have someone seen a manufactor besides Sanyo that have noise figure plots in there datasheet?

 

[hjelm]

Infineon BCW60 and BCW61; BC850 BC860; BC846 BC856;
Phillips BC850 BC860
The infineon ones have noise graphs plotted, look at the homepage under AF transistors, they are not all under low noise rather general purpose.

 

[hjelm]

Forgot Toshiba SA970 and SC2240. Their datasheets have a lot of information.
Edit: Sorry ignore these since they are not SMD
Edit again: Toshiba has low noise SMD transistors with noise graphs check Toshiba

 

[wenye]

Also you can check with Zetex, then you can find what you need there.....

 

[jcx]

you are aware that noise figure is essentially useless for low noise audio design?

national semiconductors an-104 and 222 are worth reading

 

[peranders]

Re: Low noise transistor and noise figur

Any suggestions for SMD input transistors with very low noise?

Have someone seen a manufactor besides Sanyo that have noise figure plots in there datasheet?

Unless you are planning a MC preamp or a mic amp you don't need anything more low noise than plain BC850 types, This transistor gives you around 1 uV input noise wihich is sufficient down to MM phono amps. Anything above that aren't very critical when it comes to noise if you design to minize the noise with those parts you have got.

 

[Lars Clausen]

The lowest noise audio types i have ever seen are ROHM 2SA1455k and 2SC3722k they have a noise figure of just 0,2 dB. They are suitable for normal line level impedances like 1 - 22k.

If you are looking to build an MC amp, you should use other types, like the 2SB737 and 2SD786. They have a super low noise but only if the load impedance is low (as is the case in an MC amp).

 

[peranders]

If we talk about it, SSM2210 and SSM2220 from Analog Devices are also OK but they have other unwanted properties (you can't have it all)

 

[Terry Demol]

The lowest noise audio types i have ever seen are ROHM 2SA1455k and 2SC3722k they have a noise figure of just 0,2 dB. They are suitable for normal line level impedances like 1 - 22k.

If you are looking to build an MC amp, you should use other types, like the 2SB737 and 2SD786. They have a super low noise but only if the load impedance is low (as is the case in an MC amp).

Thanks Lars. Wasn't aware of these devices. Do you know where
to locate data sheet for 1455k & 3722k?


Cheers,

Terry

 

[nuvistor]

I thought Rohm discontinued the 2SB737/2SD786.

 

[thanh]

Forgot Toshiba SA970 and SC2240.

2sc2240 is not symmetry with sa970
http://www.pcpaudio.com/pcpfiles/transistores/2SC2240.pdf
I prefer c2362 /a1016

 

[Lars Clausen]

All the mentioned types from ROHM are discontinued in production, but still widely available in DIY quantities.

There are also leaded versions of 2SA1455k / 2SC3722k, they are called 2SA1038 + 2SC2389.

I found data on these devices only in the 1990 version of the ROHM semiconductor databook (partly in japanese).
If there is any particular part of interest, i could take a JPG image and post it here.

Lars

 

[hjelm]

Tanh:
Now I am confused. Toshiba shows them as complimentary device in the spreadsheet overview of all transistors but does not mention it in the datasheet?

 

[thanh]

Really? Can you give a url which show it?

 

[hjelm]

Hope it works:
Toshiba datasheet search

 

[hjelm]

Nope.
Use the link and go via Transistors->Bipolar small sig...->General Pur...(single)

Scroll to the right in the table and there is a field for complimentary devices.

 

[Jocko Homo]

HUH???????

Since when aren't the A970 & C2240 not complimemtary? Not what my data book(s) say.

Rohm is dicontinuing the A1038 & C2389. They want us to buy the SM versions.

Jocko

 

[thanh]

Thank Hjelm!

 

[Terry_Demol]

Re: HUH???????

Since when aren't the A970 & C2240 not complimemtary? Not what my data book(s) say.

Rohm is dicontinuing the A1038 & C2389. They want us to buy the SM versions.

Jocko

Hey Jocko,

Good to see you still around.

A few BJT noise related questions for you or any other experts
here.

I am looking at MAT01 noise specs. At first they appear not so
good with around 6nV/rt Hz (P2 data sheet), but on further
inspection this appears to be at 10uA (see top of page 2).
Comparing to the super low noise MAT02, at 10uA it is pretty
similar and acheives best noise specs at a few mA.

So does anyone know what the MAT01 specs at a few mA?
Or is the data sheet wrong?

Also does Toshiba make any low noise duals of similar specs
to the 2SC2240.

Thanks for any help folks,

Cheers,

Terry

 

[Real_Macgyver]

Its always better to have as low noise in the first active stage as possible. Then after that it's of course the sound that really matters.