Gate source voltage and gate cathode voltage

In summary: Gate chathode voltage is what you see on the cathode terminal, and is typically much higher than gate voltage. This is due to the fact that your gate terminal is biased towards the source of the gate drive (typically the power supply), while the cathode is biased away from the source.
  • #1
parichay
2
0
I am studying thyrisors right now. I am really struck at trigger circuit . The book shows gate source voltage and gate chathode voltage as two different things. I fail to understand the difference and significance of them. Please help me out .
 
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  • #2
parichay said:
I am studying thyrisors right now. I am really struck at trigger circuit . The book shows gate source voltage and gate chathode voltage as two different things. I fail to understand the difference and significance of them. Please help me out .
Hi parichay. http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif

Can you provide a jpeg of the schematic and associated text where these are discussed?
 
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  • #3
Here is the image
 

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  • #4
Notice that the gate is not directly connect to Es trigger voltage source.
Voltage at thyristors gate is equal to Ug = Es * Ig*Rs. And only if Rs = 0 Ohm then Es = Ug
 
  • #5
The book shows gate source voltage and gate chathode voltage as two different things.

i think it's a question of grammar and vocabulary, not one of electronics.

Notice there's no hyphen in "gate source" inferring that's his description of the circle labelled Es, which i'd have called "gate supply" .
Gate-source is such a common phrase in FET literature it's an easy mistake to make.

Thyristors have a terminal called cathode but not one called source .
'Source' is almost synonymous with 'supply', and both could be either noun or verb,
so i think "gate source" was just a poor if excusably natural choice of wording.

My 2cents and probably overpriced at that.

old jim
 
  • #6
Always good value, Jim.
 
  • #7
parichay said:
I am studying thyrisors right now. I am really struck at trigger circuit . The book shows gate source voltage and gate chathode voltage as two different things. I fail to understand the difference and significance of them. Please help me out .
I agree with Jim. [PLAIN]http://physicsforums.bernhardtmediall.netdna-cdn.com/images/icons/icon14.gif

Gate voltage is what you see on the gate terminal, usually it's the gate-to-cathode voltage. The origin of this is typically a voltage source separated from the gate by a resistor network, or a pulse transformer, or opto-isolator, etc., and it's this voltage source that your textbook refers to as the origin or source of the gate drive.
 
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Related to Gate source voltage and gate cathode voltage

1. What is the difference between gate source voltage and gate cathode voltage?

Gate source voltage (VGS) refers to the voltage difference between the gate and source terminals of a field-effect transistor (FET). This voltage is used to control the flow of current through the transistor. Gate cathode voltage (VGK) is the voltage difference between the gate and cathode terminals of a thyristor, a type of semiconductor device. It is used to trigger the thyristor into conduction.

2. How does changing the gate source voltage affect the FET's behavior?

Changing the gate source voltage can either increase or decrease the conductivity of the FET. When the voltage is increased, the channel between the source and drain terminals becomes more conductive, allowing more current to flow through the device. When the voltage is decreased, the channel becomes less conductive, reducing the current flow.

3. Can the gate source voltage be negative?

Yes, the gate source voltage can be positive or negative, depending on the type of FET and its desired behavior. For example, in an N-channel FET, a negative gate source voltage will increase the conductivity of the channel, while in a P-channel FET, a positive gate source voltage will increase the conductivity.

4. What is the typical range of gate cathode voltage for a thyristor?

The typical range of gate cathode voltage for a thyristor is between 0 and 10 volts. However, this can vary depending on the type and size of the thyristor, as well as the desired triggering conditions.

5. How does the gate source voltage affect the switching speed of a MOSFET?

The gate source voltage can have a significant impact on the switching speed of a MOSFET (metal-oxide-semiconductor field-effect transistor). A higher gate source voltage can increase the speed at which the transistor switches on and off, while a lower voltage can slow down the switching process. It is important to carefully choose the appropriate gate source voltage for a specific application to ensure optimal switching speed and performance.

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