Question about inverters at output for driving a big MOSFET

[xibeizi]

If I want to driver a big Mosfet, why I need to connect several invetor between the output of op amp and the big mosfet. If I connect them directly, what the result will be.

 

[A.Anand Srinivasan]

Re: the driver ability

what opamp are u using.... the MOSFET doesnt need current drive to drive it... my guess is that the inverters are used for speed opamps are generally slow compared to inverters....

 

[watersky]

the driver ability

these inverters should be different size, and become the bigger step by step in order to drive big mosfet by the bigger current, because of the parasitical capacitor.It is an aim to run the higher frequency.

 

[markjiang]

Re: the driver ability

using the equal ratio inverter chain can decrease the delay, so it can make mosfet turn on fully fast in order to save the power dissipation.
this is a basic skill to drive large loading.
If the driver is analog signal, you may be not use the inveter, thus, the analog buffer is the best selection.
In fact, there is an optimum number of stage which is used to driver large capacitor. Many digital books have the equation and derivation.

 

[A.Anand Srinivasan]

Re: the driver ability

please post about the inverter chain and the MOS used in it....

 

[noname123]

the driver ability

opamp output is analog, and inverter output is digital. this question is not right. for example, if the opamp output is not at rail, the inverter right after with opamp may draw hugh amount of current. if the opamp out is at rail, you are using an opamp as a comparator, then why not just use a comparator?

 

[xibeizi]

the driver ability

My opamp is used as a comparator

 

[A.Anand Srinivasan]

Re: the driver ability

which opamp are u using... tell about the inverters too... post the circuit.........

 

[wany]

Re: the driver ability

If you connect directly, your result is a slow slew rate wave. Because big mosfet it has big parasitic cap.