Thermal resistance electronic devices and circuits

Thermal resistance does not depend on the manufacturing technology

The units of thermal resistance is celsius per watt

The typical value of thermal resistance is 0.20 celsius per watt

Common emitter electronic devices and circuits

The common emitter configuration has the highest power gain

In common emitter configuration if the collector emitter voltage increases the instantaneous operating point moves up the load line

The purpose of the emitter resistance  in common emitter amplifier is to decrease the voltage gain

Common base amplifier electronic devices and circuits

The common base transistor has got large voltage gain.

Among all other transistor configuration the common base configuration has the highest output impedance.

Among all other transistor configuration the common base configuration has the lowest input impedance.

Common base transistor provides a voltage gain.

Common base amplifier configuration provides the maximum voltage gain

The voltage gain of a common base amplifier is greater than unity.

Stability factor electronic devices and circuits

Given a fixed bias circuit the value of emitter resistance r1 r2 and beta then how to find the stability factor

Given a self bias circuit emitter resistance r1 and r2 and beta then how to find the stability factor

Given fixed bias circuit and the value of hsc then how to find out the stability factor

Given the value of emitter resistance and collector resistance base resistance and beta the type of bias is collector emitter feedback bias then how to find out the stability factor

Given a fixed bias circuit and the value of beta the value of the collector and emitter resistance is also given then how to find the stability factor

The value of stability factor cannot be less than 1

Common collector electronic devices and circuits

The common collector transistor amplifier configuration has got the largest current gain

The current gain of the emitter follower is less than unity

The other name of the emitter follower is the common collector transistor amplifier configuration.

The main application of emitter follower is it is used as an impedance matching device.

The reason why common collector transistor configuration is used for impedance matching is because it has got high input impedance.

Load line electronic devices and circuits

The graphical plot between the collector emitter voltage and the collector current is called a load line

In a given circuit the supply voltage is given

Which is the voltage at the collector is given the collector resistance is also given then at what 

voltage the load line intersects the x axis

Given a particular circuit the supply voltage is given which is the voltage at the collector the collector resistance value is given then how to find out the value at which the load line intersects the y axis

Self bias circuit electronic devices and circuits

In self bias circuit the resistor values r1 and r2 must be kept high

Given a self bias circuit and emitter resistance and the values of r1 and r2 and also the value of beta then what is the formula to find the stability factor

If there is zero dc resistance in series with the collector resistance then self bias circuit can be used

Emitter bias circuit is also called as self bias circuit

Jfet electronic devices and circuits

The junction field effect transistor is a voltage controlled current source

At pinch off voltage junction field effect transistor the drain current is zero

The junction field effect transistor is always operated by keeping the gate source pn junction reverse biased

Given a junction field effect transistor the relationship between the drain current and the saturated drain current is given then how to find out the relationship between the peak voltage and the gate source voltage in this case if the drain current is 25 percent of the maximum saturated drain current can the peak voltage will be twice the gate source voltage

When the gate to source voltage is off then it is referred to as cutoff

Fet

Field effect transistor the gate terminal represents the control input.

Digital communication systems digital communication

Digital communication system is inaccurate  than compared to analogue communication system

Signal to noise ratio digital communication

Companding results and uniform signal  to noise ratio throughout the message signal

By using matched filter what is the maximum signal to noise ratio that can be obtained

The energy per bit of a binary signal is given and the white noise spectral density is given then how to find out the maximum output signal to noise ratio in decibels

Germanium transistor electronic devices and circuits

In germanium transistor base emitter voltage is given at a particular temperature find the value of the base emitter voltage at ambient temperature

In germanium compensation takes care of the variation of the collector leakage current

In germanium the collector leakage current have a dominant effect in collector current

The temperature range of germanium is - 65 degrees to 75 degree celsius

Lag compensator control system

lag compensator helps in improving the steady state response of a system

lag compensator is a low pass filter

The beta value of a lag compensator is typically chosen to be 10

The bandwidth of a system decreases with lag compensator

Fixed bias electronic devices and circuits

Given a fixed bias circuit the values of emitter resistance r1 and r2 and also beta then how to find out the stability factor

Given a fixed bias circuit and the value of hfe then what is the formula to find out the stability factor the stability factor is 1+hfe

Given an npn transistor which is configured in fixed bias the value of rc and rl also given then how to find out the ac load line slope

Bandwidth control system

Bandwidth is inversely proportional to the rise time

Bandwidth is the frequency at which the magnitude drops to 70 % of its value at zero frequency