|
Based on this OP amp resonant oscillator, it Looks like the Parasitic capacitance of a BJT transistor in Every Circuit is about 5pF for both the Vbe and Vbc junctions, while it is about 2.5pF for the Vce junction. Calculated using the formula for LC resonance, and a tiny bit of algebra ;) Hope a lot of people find this information useful, please don’t hesitate to let me know if so! Thanks!
Summery (close approximation of results):
Base-Emitter: 5pF
Base-Collector: 5pF
Collector-Emitter: 2.5pF
*Shake to start*
Notes:
1. The frequency measurements were taken by ensuring the transistor never enters the forward biased state, so in order to measure the other regions yourself, make sure you do the same.
1a. The method I used to keep the transistor reverse biased in this example was achieved in 2 ways, both are very necessary, 1; the base is grounded, and 2; the high value (1 Megohm) resistor, cause otherwise the oscillations are too strong and end up going negative enough to forward bias the transistor, so the large resistor is there to dampen the oscillations to prevent this. So also keep that in mind in case you wanted to try a few things.
|
