Borber said:What is the value of collector inductor?
BigBoss said:Output loading affects the oscillation conditions. So when an oscillator is designed, output loading and its real and imaginary parts must be taken into account.When a load is connected hardly to the oscillator, the circuit can diverge from barkhausen conditions...
If you should use low load impedance, try to put a buffer between oscillator core and load to prevent loading effect, phase noise, pulling effect and so on...
I recommend you don't use an oscialltor standalone without buffer even the frequency low...
It's a general recommendation in practice...
VSWR said:It seems from the schematics, that the oscillator is designed for a load of 1 kohm. In that case there will be a 500 mV signal across the 1 kohm load.
Is this sufficient for your need? If not, what output level do you want? Across what load impedance? 50 ohms?
Borber said:You must use buffer stage between oscillator and 50ohm load. Such a load has too low impedance to be connected directly to oscillator.
In case of collector output try to increase load inductance from 470nH to 2uH and use emitter folover.
Buffer stage can be as simple as emitter folower in both cases.
pthoppay said:I am not sure whether you can see the oscillation at the collector terminal. The reason is, as per the cicruit there are 3 stages of operation, 1)in linear 2)cutoff 3)active.
So during the cutoff there are no oscillation in the collector terminal while at the emitter the oscillation is due to the discharge of the capacitaor through the emitter resistor.
Please refer to Crystal oscillator circuits by R.Matthys for more information.
Prakash,
What's you mean? could you explain it more because I am a beginner. Thanks!pthoppay said:So during the cutoff there are no oscillation in the collector terminal while at the emitter the oscillation is due to the discharge of the capacitaor through the emitter resistor.
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