EEVblog® Electronics Community Forum
Electronics => Beginners => Topic started by: Havass on July 25, 2023, 10:32:28 pm
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Hello,
I want to design a clapp oscillator with the transistor BFP650. But I dont know which hfe is the correct one. Without it, I can`t calculate Ic and Ib
Ty
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Design your circuit so it's not overly sensitive to variations in beta.
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Is this the Infineon datasheet?
In fig. 3 the μA number on the right traditionally indicates base current corresponding to given line. This implies β in excess of 100.
Fig. 5 and 6 can be combined to produce β estimate at 2V Vce - the result is again in excess of 100.
It looks like fig. 4 may be the wrong one.
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Could it be, that Fig. 4 has “% maximum” on the vertical scale, not A/A?
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Anyways, I guess we have to take the minimum one for calculations.
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Could it be, that Fig. 4 has “% maximum” on the vertical scale, not A/A?
Sometimes hFE is plotted as percentage of the value specified in "electrical characteristics" table. Then it would be 100% at 5mA for this part.
I guess percentage of the maximum is also a possibility, though I don't think I have ever seen it yet.
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Build a Clapp circuit properly biased like this one (https://wiki.analog.com/university/courses/electronics/comms-lab-clapp-osc) and all you'll have to worry about is the minimum beta spec.