Oscillator

I design a transistor oscillator using the MRF901. A transistor circuit oscillates when the gain of the circuit is greater than 1 and its feedback network introduces phase shift j on the output of the transistor such that -j=n2=n(360 degrees). I show that a proper selection of transmission lines on a transistor’s base, collector, and emitter nodes can generate these conditions by setting up a real negative admittance seen by the input. This design process largely takes place in ADS, so special care is taken to reduce unwanted parasitics in the real world implementation of the circuit on the duroid board.