PreferLinux :
Wrong: Analog circuits generally use the linear, and maybe cutoff regions. Digital circuits use the cutoff and saturation regions.
This is undergrad-level stuff, and you're clearly a bit out of your area of expertise. I think you have just enough rudimentary understanding to cause you trouble, because you're aware that analog amplifiers have linear input-output response, whereas any digital circuit is highly nonlinear. You're confused about what the linear and saturated regions actually mean, and you're confused by the different names used by bipolar and MOS devices.
Here's your basic course in devices:
Bipolar devices are used in the saturated region for digital circuits, so you accidentally got that one right. But no one has seriously used bipolar for digital since, oh, 1985 or so.
Bipolar devices are used in the forward active region for analog.
MOS devices are used in the triode/linear region for digital (this is the same high-slope I-V region which is unfortunately called "saturated" for bipolar devices). Here's your special warning: This does not mean that digital circuits are linear. Look at an I-V curve for a MOS device sometime.
MOS devices are used in the saturated region for analog. This is the same region called "forward active" for bipolar devices.
If you really want, I can break out some text books and quote you chapter and verse. But I'd prefer not to, considering that you could search this information on your own faster.