Electronics Engineering (ELEX) Board Practice Exam

What type of device is a Static Induction Thyristor (SITH)?

1. A 2 terminal device

2. A 4 terminal device

3. A 3 terminal, self-controlled device

4. A 3 terminal, externally controlled device

The correct answer is: A 3 terminal, self-controlled device

A Static Induction Thyristor (SITH) is classified as a 3 terminal, self-controlled device. The key aspect of this device is its ability to control current flow through its three terminals: anode, cathode, and gate. The gate terminal allows the device to be switched on and off, hence providing self-control. This self-control feature is significant because it permits the SITH to operate with fast switching capabilities and manage high power levels, which makes it advantageous in power electronics applications. Understanding the device's structure and functioning is crucial. The SITH operates in a similar manner to traditional thyristors but incorporates the benefits of voltage control via the gate. This results in a combination of self-triggering ability and efficient power handling. In contrast, classification as a 2 terminal device would overlook the crucial role of the gate terminal that is integral to its operation. Similarly, regarding the 4 terminal option, a SITH does not have the necessary additional terminal to meet that classification. The aspect of being externally controlled is also inaccurate, as the SITH can manage its own control through its internal structure, further emphasizing its characteristic as a self-controlled device.