Inverter performance
Bookmark this page:
 Yahoo!
 Google
 Windows Live
 del.icio.us
 digg
 Netscape
|
|
||||||||||||||||||||||||||||||||||
|
Posted by lerameur on September 15, 2008, 10:03 am
Please log in for more thread options Hello, I made two inverter circuit: http://www3.sympatico.ca/captoro/inverter.gif My goal is to have about 33-33v in the output to drive some mosfets. I am not about which circuit is more stable, the one with OP amp or the one below with just the Mosfets. The problem with the CMOS inverter is that I need three steps instead of two. Mainly because the gate voltage is not high enough, but I cannot put it higher then 12v. As for the OPAMP circuit, I can use the MC34071 OPAMP which has a max of 44v supply. Which circuit should I use, or any modification to be done ? thanks K | ||||||||||||||||||||||||||||||||||
|
Posted by John Popelish on September 15, 2008, 10:33 am
Please log in for more thread options lerameur wrote: They both have problems. The opamp circuit will swing the gate drives slowly, because the opamps have a slew rate limit on their outputs of a fraction of a volt per microsecond. Also, the reference voltage for both opamps should be about mid way between the swing extremes of the signal input. In the triple CMOS inverter version, you should check the current through the first stage. They are a huge load across the 30 volt supply. -- Regards, John Popelish | ||||||||||||||||||||||||||||||||||
|
Posted by lerameur on September 15, 2008, 11:10 am
Please log in for more thread options
> lerameur wrote:
> > Hello,
>
> > I made two inverter circuit:
> >http://www3.sympatico.ca/captoro/inverter.gif > > My goal is to have about 33-33v in the output to drive some mosfets. > > I am not =A0about which circuit is more stable, the one with OP amp or > > the one below with just the Mosfets. > > The problem with the CMOS inverter is that I need three steps instead > > of two. Mainly because the gate voltage is not high enough, but I > > cannot put it higher then 12v. > > As for the OPAMP circuit, I can use the MC34071 OPAMP which has a max > > of 44v supply. > > Which circuit should I use, or any modification to be done ? >
> They both have problems. > > The opamp circuit will swing the gate drives slowly, because > the opamps have a slew rate limit on their outputs of a > fraction of a volt per microsecond. =A0Also, the reference > voltage for both opamps should be about mid way between the > swing extremes of the signal input. > > In the triple CMOS inverter version, you should check the > current through the first stage. =A0They are a huge load > across the 30 volt supply. > -- > Regards, > > John Popelish Hi, Ok, I modified the circuits, let me know if this is what you meant. So the better circuit will be the CMOS gate. k | ||||||||||||||||||||||||||||||||||
|
Posted by lerameur on September 15, 2008, 11:13 am
Please log in for more thread options
>
> > > > lerameur wrote:
> > > Hello,
>
> > > I made two inverter circuit:
r
> > >http://www3.sympatico.ca/captoro/inverter.gif > > > My goal is to have about 33-33v in the output to drive some mosfets. > > > I am not =A0about which circuit is more stable, the one with OP amp o= > > > the one below with just the Mosfets.
> > > The problem with the CMOS inverter is that I need three steps instead > > > of two. Mainly because the gate voltage is not high enough, but I > > > cannot put it higher then 12v. > > > As for the OPAMP circuit, I can use the MC34071 OPAMP which has a max > > > of 44v supply. > > > Which circuit should I use, or any modification to be done ? >
> > They both have problems.
>
> > The opamp circuit will swing the gate drives slowly, because
> > the opamps have a slew rate limit on their outputs of a > > fraction of a volt per microsecond. =A0Also, the reference > > voltage for both opamps should be about mid way between the > > swing extremes of the signal input. >
> > In the triple CMOS inverter version, you should check the
> > current through the first stage. =A0They are a huge load > > across the 30 volt supply. > > -- > > Regards, >
> > John Popelish
>
> Hi, > > Ok, I modified the circuits, let me know if this is what you meant. > So the better circuit will be the CMOS gate. > > k Here is the link: http://www3.sympatico.ca/captoro/inverter2.gif k | ||||||||||||||||||||||||||||||||||
|
Posted by John Popelish on September 15, 2008, 11:29 am
Please log in for more thread options
lerameur wrote: >> Ok, I modified the circuits, let me know if this is what you meant.
>> So the better circuit will be the CMOS gate. >> >> k >
> Here is the link: > http://www3.sympatico.ca/captoro/inverter2.gif That is what I had in mind for the opamp version, but adding the resistors to the CMOS version, essentially eliminates the function of the P-channel devices. You might as well eliminate them. And, of course, you no longer have any pull up capability for the outputs, and the pull up delay for the first output also delays the pull down of the second output. What is missing is level shifting for the first stage, that turns off the P-channel device when the N-channel s on and vice versa. If you get that right, the other stages are not so bad as simple inverters (with maybe a little source resistance in all transistors to limit the shoot through current during switching). I think the next to last stage should also be built as two stages in parallel, one to drive the external inverter and one to drive the other driver, to keep the gate load on the first one from delaying switching of the second one. -- Regards, John Popelish | ||||||||||||||||||||||||||||||||||
| Similar Threads | Posted |
| Inverter performance | September 15, 2008, 10:03 am |
| Curent Fed Inverter / Voltage Fed inverter | March 11, 2006, 5:41 am |
| 68HC11 & Code Performance | September 14, 2005, 8:13 am |
| Is this a hex inverter? | December 24, 2004, 4:41 pm |
| inverter | May 22, 2006, 7:47 pm |
| DC/AC inverter | March 15, 2007, 9:07 am |
| RE:Inverter/charger | May 2, 2005, 9:52 pm |
| Building inverter for EL... how? | May 22, 2005, 1:26 am |
| DC to AC Power Inverter | April 11, 2006, 7:26 am |
| inverter - 40 volt dc to 110 ac | June 1, 2006, 10:01 pm |
| Hex inverter question | February 8, 2008, 1:39 pm |
| Inverter improvements? | August 28, 2008, 9:39 am |
| Better DC to AC inverter: Tripplite or Xantrex? | June 9, 2005, 1:18 pm |
| inverter arc-welding scheme | September 7, 2005, 7:47 am |
| Inverter Amplifier Circuit | October 5, 2005, 1:48 am |
>
> I made two inverter circuit:
> http://www3.sympatico.ca/captoro/inverter.gif
> My goal is to have about 33-33v in the output to drive some mosfets.
> I am not about which circuit is more stable, the one with OP amp or
> the one below with just the Mosfets.
> The problem with the CMOS inverter is that I need three steps instead
> of two. Mainly because the gate voltage is not high enough, but I
> cannot put it higher then 12v.
> As for the OPAMP circuit, I can use the MC34071 OPAMP which has a max
> of 44v supply.
> Which circuit should I use, or any modification to be done ?