What is a bias compensation?
Bias compensation • Compensation techniques are used to reduce the drift (change) of the operating point. • The collector to base bias and voltage divider bias use the negative feedback to do the stabilization action. This negative feedback reduces the amplification of the signal.
What is bias stabilization?
Bias stabilization: The flow of current in the circuit produces heat at the junctions. This heat increases the temperature at the junctions. increase in Increase This in turn changes the operation point.
What is the necessary of bias Stabilisation?
Bias stabilization is done to keep the operating point unaltered by the changes in the device parameters like Ico(the reverse saturation current),Vbe(base-emitter voltage) and beta(current gain). So to ensure proper stability of the operating point, bias stabilization against these variations is required…..
What are the compensation techniques?
There are other compensation techniques which refer to the use of temperature sensitive devices such as diodes, transistors, thermistors, Sensistors, etc. to compensate for the variation in currents. There are two popular types of circuits in this method, one using a thermistor and the other using a Sensistor.
What is a bias resistor?
A bias resistor built-in transistor (BRT) is a bipolar transistor with a bias network consisting of a series base resistor and a base-emitter resistor. With bias resistors built into the transistor, BRTs help reduce the number of external components required, simplifying a discrete circuit configuration.
Why does thermal stabilization occur in bias compensation?
The stabilization occurs due to negative feedback action. The negative feedback, although improves the stability of operating point, it reduces the gain of the amplifier. As the gain of the amplifier is a very important consideration, some compensation techniques are used to maintain excellent bias and thermal stabilization.
What are the different types of bias compensation?
These are the circuits that implement compensation techniques using diodes to deal with biasing instability. The stabilization techniques refer to the use of resistive biasing circuits which permit I B to vary so as to keep I C relatively constant. There are two types of diode compensation methods.
How is bias compensation used in an amplifier?
The below figure shows a self-bias amplifier with thermistor compensation. In an amplifier circuit, the changes that occur in I CO, V BE and β with temperature, increases the collector current. Thermistor is employed to minimize the increase in collector current.
Why is negative feedback important in bias compensation?
The negative feedback, although improves the stability of operating point, it reduces the gain of the amplifier. As the gain of the amplifier is a very important consideration, some compensation techniques are used to maintain excellent bias and thermal stabilization. Let us now go through such bias compensation techniques.