Design of Colpitts oscillator

[exhalt]

I need to design an oscillator, by using colpitts which will oscillate from 100 MHz to 400 MHz. The circuit should also be able to produce an output signal ranging from 100 mV to 1 V peak voltage at 100MHz.

However I have simulated and the output signal is not even 100mV. Any way that I can solve it?

 

[FvM]

In a rough estimation, the circuit output impedance is set by R3 (2k). You load it with 50 ohm, so you get 1:40 attenuation for sure, low output level can be expected.

To achieve 1 V into 50 ohm with a single transistor, it must be operated with higher bias current and respectively lower output resistor. Adding a separate buffer stage to drive the load is probably the better way.

 

[exhalt]

In a rough estimation, the circuit output impedance is set by R3 (2k). You load it with 50 ohm, so you get 1:40 attenuation for sure, low output level can be expected.

To achieve 1 V into 50 ohm with a single transistor, it must be operated with higher bias current and respectively lower output resistor. Adding a separate buffer stage to drive the load is probably the better way.

Is there any way that you can help me by telling me what values should it be in order to achieve the desired output?

 

[BradtheRad]

* C3 is unnecessarily large. Change it to 100n.

* Allow 100 to 200 nSec of build time after powerup.
After that point, oscillations increase in amplitude slowly and steadily.

* To get larger voltage swings, increase L1, reduce C1 & C2.