The transistor with high beta is used in the circuit.(beta > 100) The distinction of between voltage and power amplifier is somewhat artificial since useful power (product of voltage and current) is always developed in the load resistance through which current flows.the difference between the two types is really one of is a question of how much voltage and how much power.a voltage amplifier is designed to achieve maximum voltage is however no important to rise the power level.on the other hand a power amplifier is designed to obtain maximum output power. There is difference between voltage and power amplifiers in class A:
TRANSISTOR AMPLIFIRE FULL
If you want more gain use C3 but be prepared to put a small resistor in series with it to linearize the gain over the full desired bandwidth. Without C3 there is a voltage gain of approximately Rc / Re = 6.667. I'd use 3k0 for R2 and an 18k for R1 for practical reasons of obtainability.Ĭ3 depends on your lowest frequency input and how much voltage gain you need. R2 needs to be smaller than R1 to develop about 1.45V on the base and on a 10V supply I can immediately see that R2 being about 2k9 would take 0.5mA to develop 1.45V. R1 + R2 therefore should equal 10V/0.5mA = 20 kohm. If Hfe is 200 then current in R1 and R2 is about 10mA/20 = 0.5mA. Another rule of thumb - current thru R1 and R2 should be about one-tenth of Hfe lower than Ic. You want 10mA thru the collector and this is virtually the same current through the emitter so now you can decide what Re is - 0.75V/10mA = 75 ohms.Īt 10mA collector current you want collector to be half rail so that means Rc is 5V/10mA = 500 ohm.
This means the base will be at about 1.45V and this allows you to calculate R1 and R2 (but be prepared to revise those values should the base current drawn be a little high). I always try and get about 0.5 to 1V on the emitter (lets say 0.75V). Using E96 (1%) values for the resistors yields The DC collector current is approximately
Some of the possible design constraints are:
You need four independent and consistent design constraints to find a unique set of four resistor values. You have 4 resistors and thus, 4 degrees of freedom.
0 kommentar(er)
