Hello everyone,
I have two questions regarding the matching of small-signal, pre-driver, or power bipolar transistors, such as the BC549/559, KSC1845/KSA992,MJE340/350, MJE15034/35, or MJL4281/4302.
1) Which quantities should be closest ? Hfe, Vbe, or VbeSat ? In what order ?
2) From what tolerance do you consider that two quantities are matched ? 5%, 1%, 0.1% ?
These questions for building a high-performance Wolverine-type amplifier.
I'm taking my measurements with a DCA75 Pro.
Thank you for your answers.
Alain
I have two questions regarding the matching of small-signal, pre-driver, or power bipolar transistors, such as the BC549/559, KSC1845/KSA992,MJE340/350, MJE15034/35, or MJL4281/4302.
1) Which quantities should be closest ? Hfe, Vbe, or VbeSat ? In what order ?
2) From what tolerance do you consider that two quantities are matched ? 5%, 1%, 0.1% ?
These questions for building a high-performance Wolverine-type amplifier.
I'm taking my measurements with a DCA75 Pro.
Thank you for your answers.
Alain
There are poor designs that depend on a tight match, but those aside, you need to match devices that will cause an imbalance if not matched. Those would be power transistors that are paralleled, LTP "diff-amps" and current mirrors. Matching N and P devices may reduce 2nd order distortion but that may not be desirable. In most cases we are talking about matching Hfe.
