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What is an Ideal Switch & Characteristics of an Ideal Switch

What is an Ideal Switch & Characteristics of an Ideal Switch

An ideal switch is a switch that does not consume or dissipate power from the source & supply the whole power to the load.

What is an Ideal Switch, Characteristics of an Ideal Switch

There are a lot of different kinds of switches. Every switch has some advantages and disadvantages. The aim behind developing every new device is to make a “super device”. The characteristics of an ideal or super device can’t be achieved however characteristics can be near to ideal one. Some of the properties of an ideal switch are discussed in this article.

ON-State Characteristics of Ideal Switch

On-state is the state when the switch is ON. In this state, the ideal switch must act as given.

  • Low on-state forward voltage drop
  • It must have the ability to carry infinite high forward current
  • Low on-state resistance

Off-State Characteristics of the Ideal Switch

In the off state, the switch is completely turn off. The ideal switch in this mode must act as

  • Withstand high reverse & forward voltage
  • Low leakage current (zero leakage current)
  • High off-state resistance (infinite off-state resistance)

Characteristics during the Transition Process

The transition process can be defined as the process when the switch is turning on or turning off. The characteristics of the switch during the transition process must be as

  • Low delay time approaches to zero
  • Low rise time approaches to zero
  • Low storage time approaches to zero
  • Low fall time approaches to zero

Characteristics According to Input Requirement

 Switches are controlled by applying signals at the input. The characteristics of an ideal switch according to the applied input signal must be

  • Low gate-drive power approaches to zero
  • Low gate-drive voltage approaches to zero
  • Low gate drive current approaches to zero


The ideal switch must be completely controllable in the sense of turning off and turning off. It must be turned off by applying a signal at the gate and will have to turn off when the signal is removed. Controllability is the main condition for a switch. For e.g. Diode is a switch but not regarded as a switch because it is not controllable.

Affordable Price (cheap)

The ideal switch must be cheap in order to use it practically. The ideal switches don’t exist but there exist some switches, that are nearer to ideal w.r.t to other switches. The price of the switches is directly proportional to the idealness of the switch. In fact, ideal switches are unaffordable due to the usage of high technology and expensive materials in the manufacturing process. In short, ideal switches need to be affordable so these switches can be used practically.    

High dv/dt and di/dt Handling Capability

The ideal switch can handle high dv/dt and di/dt handling capability. As every practical switch has a limitation of not blocking infinite voltage and not allowing infinite current. Even though infinite voltage is not applied to the switch but inductors and capacitors present in the circuit produce high voltage and current spikes. These spikes damage the switch.     

Negative Temperature Coefficient (NTC)

The ideal switch must have a negative temperature coefficient. The resistance of components having NTC decreases with an increase in temperature. They have a high temperature normally while their resistance decreases when they are energized. These are mainly used as current-limiting devices and resistive temperature sensors. NTCs are preferable due to high accuracy.

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