thank you wayneh for fast replyYou could save even more battery by unplugging them both, since they don't appear to do anything.
Isn't each stage has its own biasing?The current is selected at the right level to drive the next stage properly.
are you mean because at saturation VCE not = 0, it is approx 0.4Volt?and, no, setting the collector voltage at 1/2 Vcc is just a little bit off for the best symmetry. The transistor will always need a little bit of voltage so the proper set point is a little higher than 1/2 Vcc.
Are there any relation between ICQ and VCE sat?The "little bit" depends on how much current you are using, but the basic premise is that the transistor never completely uses up zero volts.
Suppose that the second stage is another common emitter config. (not emitter follower), and suppose that one of the above circuits is intended to preamplify a Mic signal (about 10 mV peak). The designer can choose some value large or small for ICQ. On what basis the designer take a big or small value,,,, ??1) Even if the next stage has its own VOLTAGE biasing (and some of them don't), it still needs some current from the stage before it. Much like this stage that you presented, it is sitting there waiting for instructions, and whatever you want it to do will require a little bit of current to change the base current from what it is biased for. In a low voltage gain, high current stage, it will need quite a lot of current from the stage before it.
In this way may get faster to the cutoff region?2) Right. If the transistor saturates at .4 volts, you will get the best symmetry at 1/2 Vcc + .4 volts. It is as if that last .4 volts is never available for the output. In fact, the gain of the transistor decreases as it gets near saturation and that causes distortion in the output. You would bias the collector voltage even higher when distortion is important to avoid.
Yes it s for 2n3904 approx 0.05 volt @ IC = 1mA and 0.075 @ IC = 0.1mA3) Yes. If your (amps collector quiescent) is more, the Vce Sat of the transistor is higher. The datasheets go into great detail about how close to zero each transistor type can get if the ICQ is 10 ma, 100 ma, 1000 ma. It is best when a graph is supplied, but some datasheets only give a few data points.
by Jake Hertz
by Aaron Carman
by Aaron Carman