I don't think you are understanding the term offset. In LTspice, it is a DC voltage you have 'added' to the signal. In other words the input signal sits on top of this voltage. If you wish to treat that offset as part of the signal then you need to design the amp to work correctly all the way down to DC.
So your 2.5 volt offset is correctly giving a DC voltage of 6.66 volts DC at the opamp output. If you make the offset minus 2.5 volts then the opamp output becomes minus 6.66 volts.
So your 2.5 volt offset is correctly giving a DC voltage of 6.66 volts DC at the opamp output. If you make the offset minus 2.5 volts then the opamp output becomes minus 6.66 volts.
Y=mX-C, this is equation I want to implement. m=gain=2.666 , Y=output,
X=input(1.2 amplitude with 2.5 dc offset), I want this -C to implemented.
I can do it by using a subtractor but I have only positive power supply.
What to do in such a situation?
or choosing an op amp having offset of -4.865 but getting this value is not possible?
X=input(1.2 amplitude with 2.5 dc offset), I want this -C to implemented.
I can do it by using a subtractor but I have only positive power supply.
What to do in such a situation?
or choosing an op amp having offset of -4.865 but getting this value is not possible?
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Mooly,
y = mx+c is the standard equation for a straight line function.
m = slope or gradient or "gain"
c = offset from origin.
Using an op amp, m is defined by gain ratio -Rf/Rin etc, and c can be an addition fixed input summed to the output.
AFAIR (a LONG time ago!) this will need two stages, the first setting the gain, the second adding the constant. Polarities will be tricky, even more so with only a V+ supply.
'sounds like H616148 has been set a college problem?
Once again this points out the need for the OP to fully state the problem at the beginning.
I need an inst. amp goes nowhere. I need to implement a y=mx+c function, and i only have a single supply would have got us straight to this point!
y = mx+c is the standard equation for a straight line function.
m = slope or gradient or "gain"
c = offset from origin.
Using an op amp, m is defined by gain ratio -Rf/Rin etc, and c can be an addition fixed input summed to the output.
AFAIR (a LONG time ago!) this will need two stages, the first setting the gain, the second adding the constant. Polarities will be tricky, even more so with only a V+ supply.
'sounds like H616148 has been set a college problem?
Once again this points out the need for the OP to fully state the problem at the beginning.
I need an inst. amp goes nowhere. I need to implement a y=mx+c function, and i only have a single supply would have got us straight to this point!
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A good 'ole analogue computer from way back when
Thanks
Maths in pretty much any form has never been a strong point of mine. I'll be honest, seeing that equation didn't ring any bells either This is fundamental to any design... lay out your requirements, draw up a specification. A few posts back and it was mentioned that the input signal was AC and of limited bandwidth.
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