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Ultra low noise amplifiers.  (part 6)

 Overview of tested NPN and PNP transistors.

The next table gives an overview of all tested NPN and PNP transistors for which I tested the noise production.
The transistors are sorted from low to high calculated base resistance Rbb.
The properties which makes the transistor extra interesting, low Rbb or higher hfe are highlighted.

Transistor type Manufacturer View datasheet
of transistor		 NPN
or
PNP		 Calculated  transistor
base resistance
Rbb  (Ω)		 hfe
 at 25°C
Ic=10 mA 
ZTX853 Diodes inc. / Zetex ZTX853 NPN 1.62 183
ZTX851 Diodes inc. / Zetex ZTX851 NPN 1.72 185
ZTX857 Diodes inc. / Zetex ZTX857 NPN 1.72 185
ZTX951 Diodes inc. / Zetex ZTX951 PNP 1.82 200
STN951 ST STN951 PNP 2.91 300
ZTX751 Diodes inc. / Zetex ZTX751 PNP 3.76 225
PBSS5540Z NXP PBSS5540Z PNP 4.21 330
ZXTP2012Z Diodes inc. / Zetex ZXTP2012Z PNP 4.21 250
STN790A ST STN790A PNP 4.21 195
ZTX790A Diodes inc. / Zetex ZTX790A PNP 6.65 490
ZTX1048A Diodes inc. / Zetex ZTX1048A NPN 6.65 450
ZTX1149A Diodes inc. / Zetex ZTX1149A PNP 7.59 410
ZTX1051A Diodes inc. / Zetex ZTX1051A NPN 7.84 450
FZT1151A Diodes inc. / Zetex FZT1151A PNP 7.84 450
FZT1149A Diodes inc. / Zetex FZT1149A PNP 7.84 410
2SCR542PFRA Rohm 2SCR542PFRA NPN 8.35 310
2SCR533PFRA Rohm 2SCR533PFRA NPN 8.61 270
2SAR542PFRA Rohm 2SAR542PFRA PNP 9.14 320
ZTX618 Diodes inc. / Zetex ZTX618 NPN 10.58 400
2SCR552PFRA Rohm 2SCR552PFRA NPN 10.58 310
2STR2230 ST 2STR2230 PNP 11.22 600
ZXTN25050DFH Diodes inc. / Zetex ZXTN25050DFH NPN 11.57 445
ZTX690B Diodes inc. / Zetex ZTX690B NPN 13.26 860
FZT788 Diodes inc. / Zetex FZT788B PNP 14.02 725
ZXTP25020DFL Diodes inc. / Zetex ZXTP25020DFL PNP 14.47 450
2SD2662 Rohm 2SD2662 NPN 16.12 360
ZXT13P12DE6 Diodes inc. / Zetex ZXT13P12DE6 PNP 21.00 500
ZXTN25012EFL Diodes inc. / Zetex ZXTN25012EFL NPN 30.79 780
2SAR293PFRA Rohm 2SAR293PFRA PNP 56.97 490
BC327-40 Philips BC327 PNP 64.27 450
BC337-40 Philips BC337 NPN 116.56 400
BC550C Philips BC550 NPN 595.61 500




Figure 1: this graph shows the input noise density of the transistors which are highlighted in the table above.
These transistors are the lowest noise types measured for a certain hfe value.
 

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