VCO: CB colpitts 270Mhz-500Mhz

bias, so make Ie larger, use this sch use VCC==9V 

* the following image shown the inductor, just a short wire, work with parasitic induct and capacitance. as note in the above schematic, use C3==30p @280Mhz to 400Mhz, C3==2p@around 500Mhz

Dec 22, 2011

If you want high frequency with lower Ft BJT, then CB Colpitts oscillator is the best choice. Common base amplifier reduce miler effect and can operating at a frequency near the Ft. 2sc9018 Ft about 800Mhz, CB configure can work well up to 500Mhz.

* Common Base Amplifier

* work at high frequency  need a high bias, so make Ie larger, use this sch use VCC==9V

* the following image shown the inductor, just a short wire, work with parasitic induct and capacitance. as note in the above schematic, use C3==30p @280Mhz to 400Mhz, C3==2p@around 500Mhz