[Moved] Difference Amplifier

[flabbergastt]

Hi, first time posting an image, my apologies if I've posted it incorrectly.

I'm trying to get this difference amplifier working but it doesnt seem to be outputting what I want it to output. V1 = Vin V2 = -0.5v Rf=Ri, A=1 I want the output to always be Vin+0.5v so, Vo = (Rf/Ri) * (Vin-(-0.5))

Any help is appreciated, thanks!

 

[BradtheRad]

Your schematic shows NCHDM and PCHDM...

NCH and PCH would be the channel type.

Does DM stand for depletion mode? Did you intend for these devices to be enhancement mode?

 

[flabbergastt]

Your schematic shows NCHDM and PCHDM...

NCH and PCH would be the channel type.

Does DM stand for depletion mode? Did you intend for these devices to be enhancement mode?

Hey, they are dmos

 

[BradtheRad]

Your schematic is large and easy to read.

I'm looking at M6.

Questions:

* Its icon appears unusual. It has the arrow pointing away from the center, to indicate it is a P-device. However that arrow does not then connect directly to the drain or source. It connects to the positive supply rail. And neither the drain nor the source go to a supply rail.

Is M6 a device found in the simulator library, or did you construct M6?

* C2 connects to M6 (its drain or source). It blocks DC in such a position. This would be a non-typical function. Is that its purpose?

C2 will pass very high frequency AC, but only for a few cycles until it charges to a maximum DC level. Then it will no longer pass AC. Is that its purpose?