MOSFET Design Doubt: Explaining Positive Voltage

In summary: The type of MOSFET in this scenario is not specified, but it is likely an NMOS unless operated in the inverse mode. In summary, the sentence is explaining how the substrate and source connection can effectively cut off the transistor in MOSFET design.
  • #1
shawrix
18
0
Can someone explain this sentence in MOSFET design..

The Since the drain will be at a positive voltage relative to the source the two pn junctions can be effectively cut off simply connecting the substrate terminal to source terminal.
 
Physics news on Phys.org
  • #2
As far as I know the substrate and source are usually connected, and does not cut off the transistor in any way.
 
  • #3
Is it NMOS or PMOS?
 
  • #4
shawrix said:
Can someone explain this sentence in MOSFET design..

The Since the drain will be at a positive voltage relative to the source the two pn junctions can be effectively cut off simply connecting the substrate terminal to source terminal.

Since the drain is stated to be more + than the source, the device is an NMOS unless the device is operated in the inverse mode, which is almost never the case.

As stated in a previous post, the souce & substrate are usually but not always connected. That connection does not cut off the device.
 
  • Like
Likes 1 person
  • #5
shawrix said:
Can someone explain this sentence in MOSFET design..

The Since the drain will be at a positive voltage relative to the source the two pn junctions can be effectively cut off simply connecting the substrate terminal to source terminal.

... with the substrate connected to the source, the two back-to-back pn junctions cause the drain-source path to be a non-conducting path. Under these conditions (with the absence of gate voltage) the enhancement-mode MOSFET is in cut-off.
 

FAQ: MOSFET Design Doubt: Explaining Positive Voltage

1. What is a MOSFET?

A MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) is a type of transistor that is commonly used in electronic devices to amplify or switch electronic signals. It is made up of three terminals - source, gate, and drain - and operates by controlling the flow of current between the source and drain using an electric field created by the gate voltage.

2. How does a MOSFET work?

A MOSFET works by controlling the flow of current between the source and drain using an electric field created by the gate voltage. When a positive voltage is applied to the gate, it creates an electric field that attracts electrons from the source to the channel between the source and drain. This allows current to flow from the source to the drain. When a negative voltage is applied to the gate, the electric field repels electrons and prevents current from flowing.

3. What is the significance of positive voltage in MOSFET design?

Positive voltage is crucial in MOSFET design as it is used to create the electric field that controls the flow of current. Without a positive voltage, the MOSFET would not be able to function properly and amplify or switch electronic signals. It is also important to ensure that the positive voltage applied to the gate is within the specified range for the MOSFET to avoid damaging the device.

4. What are the key considerations in designing a MOSFET with positive voltage?

When designing a MOSFET with positive voltage, it is important to consider the maximum voltage that can be applied to the gate without damaging the device, the voltage level needed to turn the MOSFET on and off, and the voltage level needed to ensure the MOSFET is fully conducting. It is also important to consider the source and drain voltage levels and the overall circuit design to ensure proper functionality.

5. How can I ensure successful operation of a MOSFET with positive voltage?

To ensure successful operation of a MOSFET with positive voltage, it is important to carefully select the appropriate MOSFET for the desired application and ensure that the positive voltage applied to the gate is within the specified range. It is also crucial to properly design the circuit and consider factors such as heat dissipation and voltage spikes to prevent damage to the MOSFET. Testing the MOSFET in a controlled environment before implementation is also recommended to ensure proper functionality.

Similar threads

Engineering Depletion region capacitance in MOSFET
Replies
1
Views
774
Bidirectional current switching with single type transistor
2
Replies
42
Views
3K
Engineering Determining if voltage or current is positive or negative with sources
Replies
10
Views
4K
Will the bleed resistors enable a shorter path to ground or not?
3
Replies
80
Views
3K
Engineering Why Does Vout Become Constant in a MOSFET Circuit at High Vin?
Replies
1
Views
3K
Engineering Entrance resistance of a simple MOSFET circuit
Replies
2
Views
2K
High-Power Switching using MOSFETs
Replies
14
Views
3K
Why is the substrate terminal considered to have no effect on MOSFET operation?
Replies
1
Views
2K
Channel length modulation in a MOSFET
Replies
4
Views
4K
Engineering How to Design a Voltage Divider Circuit for Multiple Voltages?
Replies
2
Views
2K

Hot Threads

Recent Insights

Back
Top