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Okay jason, here's a extremely simplified negative resistance oscillator. Let's go through the basics of operation of it. You can see it's somewhat different than a regular oscillator - there's no external positive feedback, just the tank circuit and the NR device. The negative resistance device is actually quite crude. As the first transistor's base voltage increases, which is driven by the same supply rail as all other components in the circuit, the collector of the transistor falls. As it falls the output transistor becomes less and less open, which in turn decreases the current through it. Usually as the voltage increases, current also increases (basic ohms law). In this case, an increase in voltage causes a current drop. The biasing is made in such way, that the output transistor is kept at 1/2 the maximum current it can sink. In our case, due to emmitter degeneration, the maximum current the output transistor can sink is 13.8mA. The lowest current disables it altogether. So we bias it at around 1/2 the maximum current (6.9mA). Now all that's left is for us to add a frequency determining network on the output (the LC tank circuit), and add some gain (the 100ohm/22nF network). There's also one benefit that other oscillators lack. When using traditional positive feedback, most oscillators require a nonlinear negative feedback to enroll some amplitude stabilisation. In an NR oscillator, the output voltage mostly depends of the bias level boundaries of the NR device. It'll rise until the maximum NR current level is reached, at which point the tank circuit will not be replenished any further.
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