Section _ Fabrication and formation of programmable PUT transistors
Understanding and investigating (relaxation and relaxation oscillator mode) in a programmable field effect transistor (PUT) ( controllable transistor)
Researcher and author: Dr. ( Afshin Rashid)
The programmable unijunction transistor (PUT) offers significant improvements over conventional transistors by providing flexibility through programmable gap ratio and faster switching characteristics. These features make PUTs invaluable in applications where precise timing and reliable triggering are essential—such as relaxation oscillators, pulse generation circuits, and controlled firing of SCRs and triacs. The ability to externally adjust key operating parameters without changing the device itself increases design versatility and makes PUTs ideal for use in timing, waveform shaping, and synchronization tasks in analog and digital circuits.
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The programmable unijunction transistor (PUT) finds its primary application in relaxation oscillator circuits, utilizing its unique negative resistance characteristic to generate timing pulses. These oscillators are essential in many electronic systems where a simple and reliable timing circuit is required.
The operation of a relaxation oscillator (PUT) relies on the repeated charging and discharging of a capacitor, controlled by the intrinsic properties of the PUTthe PUT to switch between high and low resistance states based on the voltage at its emitter terminal, which makes it a natural choice for such circuits. The operation can be described as follows: Initially, the capacitor is charged through a resistor until the emitter voltage reaches the peak voltage (Vp) of the PUT . At this point, the PUT switches to its low resistance state, allowing the capacitor to rapidly discharge through the emitter to base 1. After the discharge is complete and the emitter voltage drops below the valley voltage (Vv), the PUT returns to its high resistance state and the capacitor begins to recharge, and this cycle continues, resulting in a pulsed output.
Researcher and author: Dr. ( Afshin Rashid)
Specialized PhD in Nano-Microelectronics