losses in electronic switches

It is always desired to have the power switches perform as close as possible to the ideal case. Device characteristically speaking, for a semiconductor device to operate as an ideal switch, it must possess the following features:

1. No limit on the amount of current (known as forward or reverse current) the device can carry when in the conduction state (on-state).
2. No limit on the amount of the device-voltage ((known as forward or reverse blocking voltage) when the device is in the non-conduction state (off-state).
3. Zero on-state voltage drop when in the conduction state.
4. Infinite off-state resistance, i.e. zero leakage current when in the non-conduction state.
5. No limit on the operating speed of the device when changes states, i.e. zero rise and fall times.
6. It dissipates zero power.
7. It uses little power to control its operation.
8. It is highly reliable.
9. It is small in size and weight.
10. It is low in cost and needs no maintenance.

Both during the switching and conduction periods, the power loss is zero, resulting in a 100% efficiency, and with no switching delays, an infinite operating frequency can be achieved. In short, an ideal switch has infinite speed, unlimited power handling capabilities, and 100% efficiency. It must be noted that it is not surprising to find semiconductor-switching devices that can almost, for all practical purposes, perform as ideal switches for number of applications.