Actually, what is this Virtual Ground concept?

Virtual Ground Analogy


Look at this circuit Diagram.

Virtual ground appears in the common point between two series connected resistors, if

• two voltages are applied to the other ends of the resistors,

• they have opposite polarities,

• they bear the same proportion as between the respective resistors.



Virtual ground phenomenon is summing of opposite equal quantities, which is

Latchup and its remedies:

What is Latchup?
Latch-up is a condition in which the parasitic components give rise to the Establishment of low
 resistance conducting path between VDD and VSS with Disastrous results. 


(in the figure, moat = substrate)




The start of trouble!





Electron flow builds up voltage





The forward biased source injects some holes





The holes are swept into the substrate





Voltage drop

Current Source and Voltage Source

Current Source:




----A current source is an electrical or electronic
device that delivers or absorbs electric current. A current source is the dual of a voltage source. The term constant-current sink is sometimes used for sources
fed from a negative voltage supply.





----If the current through an ideal current source can be
specified independently of any other variable in a circuit, it is

Kirchoff's Voltage & Current Laws

To learn Kirchoff Voltage & current law through animation... click the following links..



Gustav Kirchoff


Kirchoff's Voltage Law animation.. Click Here

Kirchoff's  Current law animation.. Click Here

Gate Turn-off Thyristor (GTO)-Working

GTO:
SCRs and GTOs share the same equivalent schematics (two transistors connected in a positive-feedback fashion), the only differences being details of construction designed to grant the NPN transistor a greater β than the PNP. This allows a smaller gate current (forward or reverse) to exert a greater degree of control over conduction from cathode to anode, with the PNP transistor's latched

Silicon Controlled Rectiier(SCR)-Working

SCR:

A silicon-controlled rectifier (or semiconductor-controlled rectifier) is a four-layer solid state current controlling device. The name "silicon controlled rectifier" or SCR is General Electric's trade name for a type of thyristor.











Working:
This device is generally used in switching applications. In the normal "off" state, the device restricts current to the leakage current.

Class C amplifier - Working

In class C operation, collector current flows for less than one half cycle of the input signal.




The class C operation is achieved by reverse biasing the emitter-base junction,which sets the dc operating point below cutoff and allows only the portion of the input signal thatovercomes the reverse bias to cause collector current flow. if an input signal amplitude is increased to the point

Power ampifier Class

Power Amplifier Classes







Class

A

B

C

AB


ConductionAngle

360o

180o

Less than 90o

180 to 360o


Position ofthe Q-point

Centre Point ofthe Load Line

Exactly on theX-axis

Below theX-axis

In between theX-axis and theCentre Load Line


OverallEfficiency

Poor, 25 to 30%

Better, 70 to 80%

Higher than 80%

Better than Abut less than B50 to 70%


SignalDistortion

None if

Class AB amplifier-Worrking

The Class AB Amplifier is a
compromise between the Class A and the Class B configurations above. While
Class AB operation still uses two complementary transistors in its output stage
a very small biasing voltage is applied to the Base of the transistor to bias
it close to the Cut-off region when no input signal is present.

An input signal will cause the
transistor to operate as normal in its