Could some electronics guru here please help ? What is the best way to select a transistor for an oscillator ? Consider a Colpitts oscillator running at 5 MHz. The following are the analysis steps.
- Select a value for the LC tank capacitor C1 = C2 = C
- Select a load e.g., R=50 Ohm
- To start oscillations, gmR > C2/C1. In this case gmR > 1
- Using the oscillation frequency and the LC tank capacitance value, the inductor value is obtained.
- Having determined gm, find the collector current using gm = Ic/VT where VT = 0.025
- From the VCC value, the collector current limiting resistor is VCC/Ic
- The base bias resistors are then obtained using the fact that the maximum base bias current is 0.1 times the collector current. Then the question is: how to select a transistor ?
All hints/suggestions are helpful. Thanks in advance