I'm designing an oscillator, I'm using as textbook Krauss one.
I would like to design the oscillator In function of the power it must give to the load and the fundamental frequency.
I have seen this expression in bjt amplifier design too.
According to this books, the power driven to the load (RL) is:
P = Icq2 × RL/8
So Krauss find the transistor's Q-point with this expression knowing the load and the power he wants.
I have try to deduce this equation and I have got this expression.
Let's assume the current (I) is the current across the load resistor (for example, using a simulator and measuring this signal).
P(rms) = IRMS2 × RL.
P(rms) = Ipeak2 × RL / 2.
P(rms) = Ip-p2 × RL / 8.
It's a similar expression, however it depends on the alternal current across the indictor, not Q-point.
How can I relation this expression with Q-point?
Also I have another question, let's say I have a voltage amplifier (CE). It has a gain of 2.
If the input signal is 1, I would have 2 volts in the output. So my RL with have this 2 volts signal across it, and this would generate a power.
Now I have 2 volts in the input, this will generate 4 volts in RL. So the power will increase.
According to this, the power depends on the input, the amplifier gain and the RL, not Q-point, so how does this expression makes valid ?
P(rms) = Icq2 × RL/8