n-jfet

n-jet

1. Prepared by: Nur Haziqah binti Aziz Introduction of n-type JFET n-type JFET Zero gate voltage

2. Prepared by: Nur Haziqah binti Aziz Introduction of n-type JFET Field Effect Transistor (FET)

3. Prepared by: Nur Haziqah binti Aziz n-type JFET Zero gate voltage Introduction of n-type JFET Major structure is n-type material Primarily charge carrier is electrons C omposed of a gate, a source and a drain terminal 2 p-type silicon terminals placed on either side

4. Introduction of n-type JFET Zero gate voltage Prepared by: Nur Haziqah binti Aziz Major structure is n-type material Primarily charge carrier is electrons 2 p-type silicon terminals placed on either side C omposed of a gate, a source and a drain terminal. Introduction of n-type JFET N o voltage is applied to the gate of a n-Channel JFET, current flows freely through the central n-channel. This is why JFETs are referred to as "normally on" devices.

5. Analogy Zero gate voltage Prepared by: Nur Haziqah binti Aziz Major structure is n-type material Primarily charge carrier is electrons 2 p-type silicon terminals placed on either side C omposed of a gate, a source and a drain terminal. Introduction of n-type JFET N o voltage is applied to the gate of a n-Channel JFET, current flows freely through the central n-channel. Current flows into the Drain (D), through the channel, and out of the Source (S) Without any applied to the gate terminal of the transistor, they conduct current across from drain-source region. This is why JFETs are referred to as "normally on" devices. the resistance of the channel depends on the gate-to-source voltage (V GS ), the drain current (I D ) is controlled by that voltage

6. Analogy Zero gate voltage Prepared by: Nur Haziqah binti Aziz Major structure is n-type material Primarily charge carrier is electrons 2 p-type silicon terminals placed on either side C omposed of a gate, a source and a drain terminal. Introduction of n-type JFET N o voltage is applied to the gate of a n-Channel JFET, current flows freely through the central n-channel. Current flows into the Drain (D), through the channel, and out of the Source (S) Without any applied to the gate terminal of the transistor, they conduct current across from drain-source region. This is why JFETs are referred to as "normally on" devices. V GS = 0, V DS increasing to some positive value JFET OPERATING CHARACTERISTICS Three things happen when V GS = 0 and V DS is increased from 0 to a more positive voltage: • the depletion region between p-gate and n-channel increases as electrons from n-channel combine with holes from p-gate • increasing the depletion region, decreases the size of the n-channel which increases the resistance of the n-channel. • But even though the n-channel resistance is increasing, the current (I D ) from Source to Drain through the n-channel is increasing. This is because V DS is increasing

7. Analogy Zero gate voltage Prepared by: Nur Haziqah binti Aziz Major structure is n-type material Primarily charge carrier is electrons 2 p-type silicon terminals placed on either side C omposed of a gate, a source and a drain terminal. Introduction of n-type JFET N o voltage is applied to the gate of a n-Channel JFET, current flows freely through the central n-channel. Current flows into the Drain (D), through the channel, and out of the Source (S) Without any applied to the gate terminal of the transistor, they conduct current across from drain-source region. This is why JFETs are referred to as "normally on" devices. V GS = 0, V DS increasing to some positive value JFET OPERATING CHARACTERISTICS Three things happen when V GS = 0 and V DS is increased from 0 to a more positive voltage: • the depletion region between p-gate and n-channel increases as electrons from n-channel combine with holes from p-gate • increasing the depletion region, decreases the size of the n-channel which increases the resistance of the n-channel. • But even though the n-channel resistance is increasing, the current (I D ) from Source to Drain through the n-channel is increasing. This is because V DS is increasing Drain Source 2 V 1.5 V 1 V 0.5 V

8. Analogy Zero gate voltage Prepared by: Nur Haziqah binti Aziz Major structure is n-type material Primarily charge carrier is electrons 2 p-type silicon terminals placed on either side C omposed of a gate, a source and a drain terminal. Introduction of n-type JFET N o voltage is applied to the gate of a n-Channel JFET, current flows freely through the central n-channel. Current flows into the Drain (D), through the channel, and out of the Source (S) Without any applied to the gate terminal of the transistor, they conduct current across from drain-source region. This is why JFETs are referred to as "normally on" devices. V GS = 0, V DS increasing to some positive value JFET OPERATING CHARACTERISTICS V GS =0 V DS is increased , I D increases . Therefore, I D is proportional to V DS for small values of V DS. For larger value of V DS , as V DS increases, the depletion layer become wider, causing the resistance of channel increases. After the pinch-off voltage ( V p ) is reached, the I D becomes nearly constant (called as I D maximum, I DSS -Drain to Source current with Gate Shorted ) If V GS = 0 and V DS is further increased to a more positive voltage, then the depletion zone gets so large that it pinches off the n-channel. This suggests that the current in the n-channel (ID) would drop to 0A, but it does just the opposite: as V DS increases, so does ID. At the pinch-off point • any further increase in V GS does not produce any increase in ID. V GS at pinch-off is denoted as Vp • ID is at saturation or maximum. It is referred to as IDSS. • The ohmic value of the channel is at maximum. I D vs V DS

9. Analogy Zero gate voltage Prepared by: Nur Haziqah binti Aziz Major structure is n-type material Primarily charge carrier is electrons 2 p-type silicon terminals placed on either side C omposed of a gate, a source and a drain terminal. Introduction of n-type JFET N o voltage is applied to the gate of a n-Channel JFET, current flows freely through the central n-channel. Current flows into the Drain (D), through the channel, and out of the Source (S) Without any applied to the gate terminal of the transistor, they conduct current across from drain-source region. This is why JFETs are referred to as "normally on" devices. Pinch Off JFET OPERATING CHARACTERISTICS V GS =0 V DS is increased , I D increases . Therefore, I D is proportional to V DS for small values of V DS. For larger value of V DS , as V DS increases, the depletion layer become wider, causing the resistance of channel increases. After the pinch-off voltage ( V p ) is reached, the I D becomes nearly constant (called as I D maximum, I DSS -Drain to Source current with Gate Shorted ) If V GS = 0 and V DS is further increased to a more positive voltage, then the depletion zone gets so large that it pinches off the n-channel. This suggests that the current in the n-channel (I D ) would drop to 0A, but it does just the opposite: as V DS increases, so does I D .