P
Pinchy
- Jan 1, 1970
- 0
I am building a waveformgenerator. To increase the output current I
intend to use a push pull class amplifier (NPN - PNP) in the feedback
loop of the last opamp. Hence it has to go up to 100 kHz I am looking
for the most recommended transistorset to build this stage. It should
be able to provide up to 15 V / 50 ohm (output resistance) = 300 mA in
order to get an automatic shortcut protection circuit (50 ohm acting
as a load)
The combination BC457 - BC557 (100 mA) is not suitable. The other
BD139 - BD140 (5A) is giving trouble in high frequency range as the
junctions of these are getting pretty big. The last option is a BC141
- BC161 (1A) but those are getting pretty old. Has anyone a better
idea (European parts) ? Is it usefull to bypass the collector - base
junction with Schottky diodes (as in digital 74LS, ALS, AS, ...) to
inprove the discharge speed of the collector junction ?
Thanks
Ing. Geert
intend to use a push pull class amplifier (NPN - PNP) in the feedback
loop of the last opamp. Hence it has to go up to 100 kHz I am looking
for the most recommended transistorset to build this stage. It should
be able to provide up to 15 V / 50 ohm (output resistance) = 300 mA in
order to get an automatic shortcut protection circuit (50 ohm acting
as a load)
The combination BC457 - BC557 (100 mA) is not suitable. The other
BD139 - BD140 (5A) is giving trouble in high frequency range as the
junctions of these are getting pretty big. The last option is a BC141
- BC161 (1A) but those are getting pretty old. Has anyone a better
idea (European parts) ? Is it usefull to bypass the collector - base
junction with Schottky diodes (as in digital 74LS, ALS, AS, ...) to
inprove the discharge speed of the collector junction ?
Thanks
Ing. Geert