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Can load network Rload=-Rout/3 rule be used for source network impedance?

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Terminator3

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Many sources mention than after oscillator power build up Rout (real part of output impedance) becomes less negative, so Rload=-Rout/3 value is used to ensure oscillations. What about Rin (real part of input impedance)? Can this principle also be applied at the input of oscillator? I mean can we use Rsource=-Rin/3 instead?
 

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Thank for your reply! Can you give reference to your book?

"RF Circuit Design Theory and Applications, Second Edition" Reinhold Ludwig, Gene Bogdanov
page 475:
Usually, the power dependence of transistor's small-signal S-parameters results in a less negative Rout = Re(Zout) for increasing output power. Thus, it is necessary to choose Rl=Re(Zl) such that Rl+Rout<0. In practice, a value of Rl=-Rout/3 is often used.
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So it seems that rule can be used at any port, input or output.
 

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