I am trying to design an Oscillator circuit which can produce a good sine wave with a frequency of at least 500 Mhz and oscillating voltage of around 10 - 15 volts. The output of this oscillator will be just connected to a two Conducting plates of 1 Square inch(one to Collector output and the other plate to ground, with 1 inch gap between the plates). Therefore the resistive loading is just the tuned circuit losses.
I tried learning to design my own oscillator but ended up getting confused reading the data sheet parameters, especially hfe (Current Gain) of various BJTs.
I have been told that in order to get 500MHz I need a transistor with a transition frequency of 5GHz .I thought that a gain above unity above circuit losses would be adequate for sustaining oscillations .
The things I do not understand are as follows :
- How do I set the operating point for the amplifier for a colpitts oscillator to get the desired oscillating voltage?
- what is the voltage gain of the amplifier (Voltage divider bias used for biasing of transistor), thus I am stuck up in calculating the feedback fraction for the amplifier to sustain the oscillations. I understand that the ratio of capacitors of the tank circuit is the feedback percentage, but without knowing how to calculate the voltage gain of amplifier I am unable to proceed further.