hi there,i would like to to how to invert -2V of the sine waveform?
because i want to generate the unipolar spwm to apply n-channel MOSFET to my h-bridge.

In practically,what is the component that suitable to invert sine waveform with 180 degree with respect to 2V sinewave as show on the figure below.

by inserting the inverting amplifier at the pin 2 of op-amp,U7?

 

Your circuit can't work. The 2.5 volt input will overpower the 2 volt inputs, and the outputs are tied to ground.

An op amp set up as a 1:1 inverter will do what you want.

 

Your circuit can't work. The 2.5 volt input will overpower the 2 volt inputs, and the outputs are tied to ground.

An op amp set up as a 1:1 inverter will do what you want.

i want to make my modulation amplitude=0.8,that's why i set it like that.As you know that the reference sine wave divide by carrier wave is equal to Ma.

practically,i had try to invert the sine wave in lab by using the op-amp,u741,but still cannot get the invert sine wave.

how to get the sine waveform as show in the attachment?

 

An op amp can easily invert the sine wave. Here is the material from our Ebook - http://www.allaboutcircuits.com/vol_3/chpt_8/5.html

The attached illo from the chapter shows how it's done.