LLQ oscillator

156

03:46:22

I just wanted to make an oscillator using a transistor's internal capacitances. ;)

I think this is the minimum spec' transistor tht would work.  Internal resistances are 10mR.  100mR is too much.  I'm not sure what that says about upper limits of inductor parasitic resistance, but I guess the larger value the inductor, the less the resistance matters.

published 7 years ago

hurz

7 years ago

Interesting, two coils in sum they have 1.9nH the frequency 1.63GHz so if we calculate what must be the capacitance to get this resonance we get 5.01777pF from pin to pin there are 5pF at everycircuit transistor build in parasitics. If the frequency could be measured more precise the result seems to be exact 5pF

eekee

7 years ago

Odd.. that means the frequency shouldn't round to 1.63GHz, it should be 1.63579 rounding to 1.64GHz. Or maybe 1.62422 rounding to 1.62GHz. Or maybe I'm taking the calculations too far. :)

hurz

7 years ago

I have tsken 1/[(1.63GHz × 2pi)² × 1.9nH] = 5.01777pF so everything depends on the exact frequency we have here

eekee

7 years ago

I keep telling myself to work it out, but my brain's just pfft.

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