Hello,
The colpitts oscillator circuit has come up many times is this forum but I can't find one regarding transconductance of the circuit. (Circuit is attached)
So lets say initialy the circuit is not oscillating, and I have 1.7V going into the base of the transistor. ≈0.7V will be dropped accross the diode leaving 1V accross R2. If R2 were to be equal to 1KΩ, Ie would equal 1mA there for I can assume that gm small signal equals 1mA/Vbe(26mV) = 0.038, correct me if I'm wrong. Once the circuit begins to oscillate, and that theres 156mV signal going into the base 1.156V will be accross R2 meaning now that I will have a Gm large signal of 1.156mA/Vbe(26mV) = 0.044??? Is this correct?
I'm reading a book, and its showing calculation for the axact same circuit below. Initialy circuit isn't oscillation R2=1kΩ at 1V giving an mho of 0.038. When it start oscillating he says that theres 0.156mV signal going into the base makings 1.156V accross R2 giving mho of 0.044 but the book says Av=gm/Gm, gain was equal to 3.2 gm=0.038mho which means that Gm would have to ve equal to 0.011875mho.
How does this make sense I calculate 0.044mho and the book says 0.011875 mho?
Thanks
The colpitts oscillator circuit has come up many times is this forum but I can't find one regarding transconductance of the circuit. (Circuit is attached)
So lets say initialy the circuit is not oscillating, and I have 1.7V going into the base of the transistor. ≈0.7V will be dropped accross the diode leaving 1V accross R2. If R2 were to be equal to 1KΩ, Ie would equal 1mA there for I can assume that gm small signal equals 1mA/Vbe(26mV) = 0.038, correct me if I'm wrong. Once the circuit begins to oscillate, and that theres 156mV signal going into the base 1.156V will be accross R2 meaning now that I will have a Gm large signal of 1.156mA/Vbe(26mV) = 0.044??? Is this correct?
I'm reading a book, and its showing calculation for the axact same circuit below. Initialy circuit isn't oscillation R2=1kΩ at 1V giving an mho of 0.038. When it start oscillating he says that theres 0.156mV signal going into the base makings 1.156V accross R2 giving mho of 0.044 but the book says Av=gm/Gm, gain was equal to 3.2 gm=0.038mho which means that Gm would have to ve equal to 0.011875mho.
How does this make sense I calculate 0.044mho and the book says 0.011875 mho?
Thanks
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