The voltage or Potential divider bias or the self bias circuit is the best biasing technique because,it has very low stability factor(change in collector current with respect to Ico or Vbe or current gain beta). only in this technique the increase in temperature wont affect the collector current.
dc characteristics:- 1.input off set voltage, 2. input bias current, Ac characteristics:- 1, commen mode rejection ratio, 2. slew rate
forward bias is in the direction a junction or vacuum tube wants to conduct currentreverse bias is in the direction a junction or vacuum tube opposes conducting current
When a diode reduces the input voltage, it typically operates in the forward bias condition, allowing current to flow while dropping a specific voltage across it, known as the forward voltage drop (usually around 0.7V for silicon diodes). This voltage drop occurs due to the energy required to overcome the potential barrier of the diode's p-n junction. As a result, the output voltage is lower than the input voltage by this forward voltage drop, effectively regulating the voltage in circuits like rectifiers or clamping applications. In reverse bias, a diode ideally blocks current flow, maintaining the input voltage level until breakdown occurs.
Bias is a permanent voltage, applied to the input of an amplifier device, in order to make it work in the correct area of an amplification curve. Valves (thermionic tubes) and semiconductors (transistors) both use bias in their grid or base connection. A negative swing in the input could put the control input below the working of the device and cause it to switch off. This is undesirable as it will show as distortion. The bias raises the zero point, so that the signal will not turn the device off.
A: difference in bias current causes the other
The voltage or Potential divider bias or the self bias circuit is the best biasing technique because,it has very low stability factor(change in collector current with respect to Ico or Vbe or current gain beta). only in this technique the increase in temperature wont affect the collector current.
On the emitter there is base current which is basically a function of Beta and only at that particular current. Unfortunately the beta factor is a non linear function and it is strictly related to collector current
The Self Bias of the BJT is also called the voltage divider bias. It is called thus because it can stabilize the collector current, the base emitter voltage and the amplification factor.
for a collector to base biased circuit find the stability factor s?what is the effect on s for change in current amplification factor?
dc characterstics : 1.input offset voltage 2.input bias current 3.input offset current 4. thermal drift ac characterstics:1. CMRR 2. SLEW rate 3. rise time
The input signal is assumed to have zero DC bias. Input stages will typically have a positive bias on the base or grid, respectively, of the first stage transistor or tube. So, the input terminal is more negative. ANSWER: The polarity of the capacitor is determined by the bias polarity as used. If the bias is negative then the capacitor negative terminal must be connected to it.
dc characteristics:- 1.input off set voltage, 2. input bias current, Ac characteristics:- 1, commen mode rejection ratio, 2. slew rate
for a BJT to amplify we give input signalif suppose we use BJT in CE configuration input is given at Emitter-Base junction and output is taken at Collector base junctionthe input voltage increases or decreases the forward bias of the E-B junction affecting a change in the base current and we know that collector current is a function of base current collector current also variesso by selectively changing the base current we can effectively change the collector current
low input impedance
An ideal diode:Passes current in one direction only. (Under forward bias).Has no leakage current (passes no current under reverse bias).Has no forward voltage drop. (No voltage loss under forward bias - a real diode has Vd~=0.7)See links for more details.
Diodes will have a small leakage current in reverse bias. In most cases, this current can be considered insignificant and ignored.