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Design >> Mixed-Signal Design >> feedback capacitor in a hartley osc
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Message started by svensl on Jul 6^th, 2006, 11:59pm

Title: feedback capacitor in a hartley osc
Post by svensl on Jul 6^th, 2006, 11:59pm

Please consider the common base oscillator shown in the figure below. My question concerns the capacitor Cf which should only pass RF components.
1) How does one size this capacitor as it is responsible for the bandwidth of the feed-back network?
2) When simulating the hartley osc. as shown in the figure, changing Cf does not change the frequency of oscillation. However, when implementing the circuit on a breadboard changing Cf does significantly change the frequency of oscillation. Why is that?
Thanks